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1998 Dodge B1500 turn signal staying on

13K views 67 replies 7 participants last post by  Laser86  
#1 ·
This is what is happening, been happening since I got the vehicle (I thought it was intermittent so never got around to trying to figure out why and when this was happening).

If the the ignition is on, and the turn signal is on, and you turn the ignition off, the turn signal keeps blinking indefinitely (either left or right).

If the ignition is on, and the turn signal is off, and you turn the ignition off, if you turn the turn signal on, within roughly 15 seconds, the turn signal will come on and blink indefinitely.

If the ignition is on, and the turn signal is off, and you turn the ignition off, if you turn the turn signal on, outside of roughly 15 seconds, the turn signal will come not come on.

Newer, NOS multi-switch off Fleabay. (looked unused, still had protective web covering over the lever and paint markings looked unscratched).

Newer turn signal / flasher relay. (tried another Brand New turn signal / flasher relay, same thing).

Newer ignition switch.

Wondering if anybody else encountered such an issue. Steering column covering has been off since I got this van, would like to re-install it but would like to try and figure this out first.
 
#2 ·
Any wiring mods from a previous owner, trailer tow harness or conversion van accessory relay?
It almost behaves like it is on a timer?

I would almost suspect a 'feedback' or 'cross-over' from battery-powered lines into ign-powered lines, but it is only the turn signals that do this? No other accessories power on with the key off?
A crossed circuit in the combination flasher circuit could power the turn signals from the hazard flasher circuit?

An accessory relay kept 'ign-powered' things on for a selectable amount of time after removing the key. It may be hanging loose under the dash (if equipped). There is also a hidden relay bank behind the glove box bin. I don't understand the 15 second delay though.

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#4 · (Edited)
Does not appear to be any modifications to the wiring, wiring actually appears to be in good condition, does not appear that there has been any trailer hitch wiring installed, even appears to be the original factory AM/FM radio (although the FM does not work, and it took several months before the clock and AM started working again)..

Here is some more information.

With ignition off, removed turn signal / flasher relay, turned ignition on, turned ignition off, installed relay within 15 seconds, turned on turn signal immediately after installing relay, turn signal came on.

With ignition off, removed turn signal / flasher relay, turned ignition on, turned ignition off, installed relay after 15 seconds, turned on turn signal immediately after installing relay, turn signal came on.

With ignition off, removed turn signal / flasher relay, turned ignition on, turned ignition off, installed relay, waited 15 seconds then turned on turn signal, turn signal did not come on.

Appears the delay is somehow within the turn signal / flasher relay.

Both relays are Standard Brand, purchased about 10 months apart.

This is why I never messed with this, it was just easier to try and to remember to make sure the turn signal was off.

Also, with the ignition off, when you plug in the turn signal / ignition relay you can feel and hear a slight ' click ', which I would think you should, but ....
 
#5 ·
I am thinking it is posible that you have a poor ground connection. Typically there are multiple eyelets stacked at a ground location. The eyelet next to the body has a poor ground / excessive resistance. Other circuits grounded at the same location are causing a back feed of electrical current. This is finding its way back to the flasher device and causing the strange behavior outlined. Check ground locations in attached diagram. Not sure but would expect to find ground locations in / around / near PDC (power distribution center).

 
#6 ·
Makes sense, took a quick look, drivers side rear flasher bulb is not as bright as passenger side (I know this can happen when you lose a ground), suspecting a possible issue with that, what is the S for in S319, a splice ? Any idea where this G301 (assuming G is for ground) is located ? Took a quick look and did not see any grounding eyelets underneath the rear or alongside toward the front of the van, would they typically ground these wires at the front of the van (since steel is not as good of a conductor of electricity as a piece of copper wire and also because body weld joints, over time, can cause conductivity issues) ? Thinking it may be an issue from S319 to the socket, or at the socket itself, or both rear bulbs would be affected, maybe.
 
#9 · (Edited)
Long story here ....

Drivers side bulb not being as bright as the passenger side bulb ended up being some rust on the wire extruding from the bulb itself, cleaned that, same problem, HOWEVER, when the tail cover was off noticed that when the running light was on, and the turn signal / hazard light would flash, the running light filament would go out, this was happening to both the drivers and passenger side bulbs.

Figuring that was caused from a faulty ground I searched for and located the eye connector ground next to and slightly behind drivers side seat, cleaned that, same problem. Even ran a ground wire directly from the negative on the battery to the ground wire I slightly skinned at the rear wiring harness close to the rear connector, same thing, tail filament would go out when turn signal / hazard light would flash, thinking this can't be right, removed the front turn signal covers to look at those filaments, just to make sure my eyes weren't playing tricks on me, running light filament DID NOT go out when the hazard / turn signal filament would flash, this was a problem just with the rear lights, even removed the tail cover of my '02, running light filament DID NOT go out when hazard filament came on, so this was a problem exclusively with the '98 ...... tested this voltage, tested that voltage, figuring none of this makes any sense .....

Luckily I had a spare connector from my '03, connected the ground wire from the battery to the ground wire on the connector and pushed the other two wires into the 98 connector, worked normal.


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Then I took a closer look at the wires themselves.

Driver side connector next to the '03 connector.

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Passenger side connector next to the '03 connector.

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The ground wire and the brake / turn signal / hazard wires are backwards, my guess is it came this way from the factory, the wires or wiring harness do not appear to be altered ...... think my buddy said he has a tool that can remove those pins, otherwise I will splice and solder them in their proper order ....... whatever, smh ....

Thanks for all of the assistance, I may have figured this out on my on, eventually, maybe .... maybe not.
 
#18 ·
. . . .Luckily I had a spare connector from my '03, connected the ground wire from the battery to the ground wire on the connector and pushed the other two wires into the 98 connector, worked normal. . . . .
I am thinking that the wire harness to the left rear lamp assembly ( tail, stop, turn ) has been replaced. I suspect someone went to a salvage yard and found a similar van. Cut the 3 wire harness inside the van (wire penetrates grommet on body) and made a splice. The black wire ground inside the body is bad.

The attached image captures your pictures of the LR and RR 3 wire electrical connector at the lamp assemblies. Note that the wire for the dual filament bulb for tail and stop / turn signal has a different color between left and right. That would NOT be OEM from the factory. I reviewed different year service manuals for Ram trucks and the same wire function between left and right would use the same color wire with tracer for the same model year. So that tells one that the LR wire harness has been replaced.



Follow that 3 wire harness at the LR through the grommet and inside the body. See if you find a location where it has been spliced into the factory wiring harness. Check the black wire splice. I am thinking the ground splice is bad and causing feed back and the strange behavior of the turn signals.
 
#10 ·
Did not come that way from the factory, I guarantee you.
What almost certainly happened was that at some point in the past, a previous owner DID have a trailer plug setup, and did that to the wires, then never restored them when it was removed.
 
owns 2011 Chrysler 200 Limited
#11 · (Edited)
Sure it more than likely came that way from the factory, they just inadvertently switched the two wires while fabricating the harness.

I am not even sure those pins can be removed from those connectors, I think a buddy of mine told me he had a tool that could, I am not even sure this tool will even work on this type connector. If somebody had that tool, and the ability to switch those pins, then more than likely they had the ability to look underneath the van and see the already existing factory trailer wiring connector. There would be no logical reason for anybody to switch those pins to wire a trailer. And with the brighter of the two filaments receiving full voltage, just reversed, and other than the turn signal occasionally staying on everything would function as normal, kinda. As far as anybody knows the van has been in the shop multiple times due to the turn signal issue, but nobody was able to figure out why, I mean where or how would you even begin the check something like that ? I just got lucky I had a spare connector and happened to notice the wires were switched, and access to the wisdom, and expertise, and knowledge of this website.
 
#12 ·
A small jewelers screwdriver may help depress the terminal barb and allow disassembly after prying out that yellow plastic retainer block and soft, orange rubber seal at the back of the connector.
 
#15 · (Edited)
Ok, caught up with my mechanic friend, used tool kit to swap wires, the running light filament is now staying on when the turn / brake / hazard filament lights, HOWEVER, having same issue with turn signal staying on when the ignition switch is turned off.

Figuring I may have gotten a few bogus turn / hazard relays went AutoZone and got a different brand, same issue, only difference is that the 15 second delay turned into a 25 second delay, so re-installed old relay.

However, it rained today, and what I noticed was this .....

If the multi-switch / wiper motor is on either low, or high, and the turn signal is on when the ignition switch is turned off, the turn signal will SHUT OFF and STAY OFF.

HOWEVER, if the multi-switch / wiper is in delay mode, and the wiper motor IS NOT moving and the turn signal is on when the ignition switch is turned off then the turn signal will STAY ON, HOWEVER, if the wiper is in the delay mode, and the wiper motor IS moving and the turn signal is on when the ignition switch is turned off then the turn signal will SHUT OFF and STAY OFF.

So somehow the turn signal circuitry seems to be electrically connected to the wiper delay circuitry is my guess. Which is why I never spent a lot of time trying to figure this out, it just seemed to do it randomly.

Here is a picture of the multi-switch harness connector plugged into the ignition harness connector. I wouldn't think the multi-switch would do much of anything if the connectors were not installed properly, the turn signal / hazard / brake / wiper / bright all seem to be working normally.


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#16 · (Edited)
Only thing I can think of is maybe there is wire landed in the wrong spot on the multi-switch, or a wire is landed in the wrong spot in either the multi-switch harness connector or the main wiring harness connector where those two connectors meet. Or unless the wiper delay relay is bad, but I just can't see a bad wiper delay relay causing this problem. I still have the broken multi-switch that came with the van, I will try and match the wires on the switch and at the connector and see if they are located in the same spots. IMO these circuits should be completely separate and no way should have the opportunity to be crossed internal to the switch or elsewhere.

Maybe it is a bad wiper delay relay, and it is somehow feeding voltage back through the ignition circuit, I think I have one laying around from the '03.
 
#17 ·
Installed wiper delay relay from the '03, same thing.

Ignition off, wipers off, engaged turn signal, turned on ignition, turn signal came on, turned off ignition, turn signal stayed on, turned wipers to low, turn signal turned off.

???????????????????????????????
 
#19 · (Edited)
Just went out and looked again, the wiring is intact, no cuts or slices.

To clarify, regarding removing the pins, probably could have figured that out and done that myself, but some reason I am not good at separating connectors or other stuff like that, some kind of mental block or something, so I wanted dude to show me how to remove the pins, and his universal kit didn't even have the best tool, a better tool would have been a flat 1 mm thick piece of steel 3 mm wide about 4 inches long.

According to post #2

Left - left tail

PIN 1 BK - ground
PIN 2
PIN 3 DG / OR - stop / turn

Right - right tail

PIN 1 BK - ground
PIN 2
PIN 3 BN / RD - stop / turn

The DG looks correct for the left side, not sure about the stripe, and BN looks correct for the right side, not sure about the stripe

Assuming PIN 2 (which is blank) is for the running lights which should be the same for both left and right - BK / YL

It was around 8 months ago, but I think the connector I cut from the '03 was the front right, which matches TN / DB that I pictured.

The left and right rear running and turn bulbs / filaments are both working properly now, they were not before because PINS 1 and 3 were switched on both the left and right sides.


Off the wall question, is there an outside chance there is a service bulletin on this van ? Seems like a pretty simple circuit, but both my '02 and '03 had / have a double relay which I am assuming is for the turn / flasher, opposed to the single relay on the '98, why would they change that on a basic cargo van ?

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#24 ·
. . . .Just went out and looked again, the wiring is intact, no cuts or slices.
. . . .
According to post #2

Left - left tail

PIN 1 BK - ground
PIN 2
PIN 3 DG / OR - stop / turn

Right - right tail

PIN 1 BK - ground
PIN 2
PIN 3 BN / RD - stop / turn
. . . .
The left and right rear running and turn bulbs / filaments are both working properly now, they were not before because PINS 1 and 3 were switched on both the left and right sides. . . . .
Having the ground wire on the stop / turn sgnal feed side and the stop /turn signal feed side serving as ground would cause the strange lamp behavior. But this would mean that the OEM supplier to the factory assembly line made a mistake with the wiring harness. And this means the rear signals did not work properly when the vehicle left the factory. And the original owner of the van never brought up a waranty issue? But if this was a fleet vehicle with many different drivers, then no one would notice and / or care if the turn signals and tail lamps worked properly in the rear. Glad you solved the issue.

. . . Seems like a pretty simple circuit, but both my '02 and '03 had / have a double relay which I am assuming is for the turn / flasher, opposed to the single relay on the '98, why would they change that on a basic cargo van ? . . . .
I wonder if the double relay in the later model vehicle incorporates a front DRL (daytime running lamp) feature? That would explain the extra pins.
 
#20 ·
The factory service manual will have complete wiring diagrams.
Despite the overall design not changing much, there were advances till going on. For example, there was a switch away from mechanical to electrical flashers and this may explain the differences.
 
#21 · (Edited)
I noticed that, despite the overall design not changing much, there were still slight advances going on from year to year ...... even from '02 to '03 .... '03 had rear brake disc option, heavier front springs, 16" rims ... '03 was like the culmination of everything good into one, then they discontinued it ....
 
#22 ·
Is it a bad (high-resistance or open) ground feeding battery (park lamp) voltage through the other filament into the (directional lamp) with the key off? This 'feedback' may go back to the solid-state flasher and after a moment, feed through start operating the turn signal with the key off?

The poor ground may be at or in the lamp socket. Any signs of moisture corrosion in front or rear lamps?

It may not show on an ohmmeter test, but it may show in a voltage drop test (a single strand of wire will measure 0Ω, but will have an excessive voltage drop trying to pass current).
Are they the correct 3157 lamps front & rear?
Image
 
#23 ·
I will double check the bulb numbers, I was wondering how those bulbs and sockets were configured, thank you for the illustration, not like the old school ones where you can easily tell.

The sockets do not look corroded, not perfectly clean, but not corroded .... looks like they are still available at Rock Auto, thinking of getting 4, pretty sure they are interchangeable left to right and front to back, that should help prevent a future loose connection to hopefully avoid getting pulled over one day who knows where for a non-functioning brake or turn signal light.

I am still trying to figure out what I described in POST # 17

Installed wiper delay relay from the '03, same thing.

Ignition off, wipers off, engaged turn signal, turned on ignition, turn signal came on, turned off ignition, turn signal stayed on, turned wipers to low, turn signal turned off.

???????????????????????????????


Plan on yanking the multi-switch later this evening to take a closer look at it.

So if this is an electronic relay will that prevent me from switching to 3157 LED bulbs ? I see there are some plug and play 3157 LED bulbs on FleaBay.
 
#27 · (Edited)
. . . I am still trying to figure out what I described in POST # 17

Installed wiper delay relay from the '03, same thing.

Ignition off, wipers off, engaged turn signal, turned on ignition, turn signal came on, turned off ignition, turn signal stayed on, turned wipers to low, turn signal turned off.

??????????????????????????????? . . . .
The real challenge in solving this issue is that no one has an accurate, correct model year factory wiring diagram for a 1998 B1500 van. We can look at diagrams for pickup trucks around the 1998 time frame but that could be misleading. There are wiring changes from year to year and changes due to replacing electro-mechanical components with solid state devices and differences due to varying vehicle configurations.

I looked at a wiring diagram for a 1998 Dodge Durango. That diagram shows a combination, electronic flasher mechanism in the turn signal system. I then looked at the wiper motor diagram and it shows a 6 pathway connector at the wiper motor (only 5 wire paths used). The ground is through a BK wire to G101.

In post #2 dated Apr 22, 2022 ImperialCrown provided a wiring diagram that shows the front turn signals grounded at G101. If G101 has a poor ground connection could the wiper motor be providing an electrical back feed through G101 to the electronic flasher and causing the weird behavior of the turn signals???? I would suggest checking the ground at the wiper motor electrical connector and onto ground G101. Hopefully this is not an adventure down a "rabbit hole".
 
#25 ·
When you check the bulb types, remove the bulb & flip it 180Âş before plugging it back in. Look in the socket for signs of tarnish or heat distress.
The difference in brightness between left & right (post #6) could indicate a poor ground with feedback through the parking lamp filament.
Do the lamps look OK, equal (brightness-wise) from outside the vehicle with both the parking lamps & turn signal on?
Has the dash turn signal indicator ever glowed dimly with the parking lamps on?
 
#28 ·
The B-van wiring diagrams are different enough than the D-trucks & Dakotas as to be misleading. Nomenclature & wire colors can be different.
The online service information provided to Chrysler dealerships on vehicles that are over 20 years old leaves something to be desired. The original paper manual is better.
True that the B-van didn't change much year over year until the Sprinter took over for 2004.
I can get most of the wiring info you need.
 
#29 ·
Poor ground location images. Barely readable. I've highlighted the ground points, but it seems incomplete.
The wiper motor 'park' switch (where it lifts ground during intermittent (delay) wipe and motor shutoff is inside the CTM. The CTM is like a BCM, but simpler.
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#31 · (Edited)
Thank you for all of the responses, I will read each one of them thoroughly to make sure I understand each one, quite a bit to digest.


Another off the wall question, is it possible that the aftermarket replacement relays are not compatible with the OEM wiring ? Or is this just a standard type relay ?



I thought the ignition switch / harness was replaced due to previous owner having a starting issue, ended up being the neutral safety switch, I don't think it was replaced, but he did send a new one with the van, I installed it this evening, same issue.
 
#34 ·
. . . .Another off the wall question, is it possible that the aftermarket replacement relays are not compatible with the OEM wiring ? Or is this just a standard type relay ? . . . .
Standard electro-mechanical relays would be widely interchangeable with any wiring system. As long as the spade terminals align with receptacles in the adjoining socket and the relay contacts are built for the design amperage load, then there will be no compatibility issues.
 
#36 · (Edited)
Ok, apparently the 1998 Dodge van wiper motor has a different style connector

Image




There is a copper ground strap (located at top of previous picture, the wiper motor will not function without this strap connected), one end of strap is riveted to the wiper motor housing, the other end is grounded by one of the 3 wiper motor mounting bolts, I removed and cleaned that, along with the metal bushing spacer.

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Not being sure if where the copper strap was riveted to the wiper motor housing was making a good connection I ran a ground wire from the wiper motor housing straight to the battery.

Image



I also cleaned these ground connectors.

Image



Same issue.


Copper grounding strap disconnected (wiper motor will not function) - turn signal on, ignition on, ignition off ... turn signal will keep flashing regardless position of wiper function control, delay / low / high.

Copper grounding strap connected - same as before, if the turn signal is on, if the wiper is on, and the wipers ARE NOT resting, when you turn off the ignition the turn signal WILL turn off, regardless whether wiper function control is in delay / low / high, this only seems to be an issue when the wiper motor is in the resting position whether or not the wipers are on.


This does not need to be fixed anytime soon, it has been this way since I owned the van, almost a year, the turn signal only stays on if I do not straighten the wheel before I cut off the ignition, which is not often, however, I was wanting to button up the bottom of the dash and the plastic casing around the steering column, also, I do not like getting beat by anything, especially something that should logically be able to be figured out, electricity is logical, however, I also have to weigh what is practical, I would be content wiring in an additional relay somewhere to cut off the turn signal or whatever else is causing this issue, especially if repairing this is going to entail a large undertaking (wiring in a relay is what I thought I may have to do originally), seeing how this is 1998 van I am not looking for perfection, installing a relay would be fine. There are many other things that I need to repair on this van. I could also break off this for now and return to it later.

I am clueless here, I will continue to look over the wiring diagram(s).

* note : both the wiper motor and turn signal are on the accessory (when the key is turned backwards), if this means anything.

Is it possible the resistance of the flasher relay is lower than OEM therefore allowing the electricity to somehow find ground through the least path of resistance, IE the relay ? I know all relays should basically be the same, but another brand flasher relay did change the delay I first described from 15 to 25 seconds (POST # 15).

Thanks for all of the help to this point, I appreciate it, I know this has been time consuming.
 
#38 ·
. . . .Ok, apparently the 1998 Dodge van wiper motor has a different style connector

View attachment 87427
. . . .
This invalidates my hunch that a shared, common ground point for the wiper motor was somehow providing feedback to turn signal system. The wiper motor has its own, unique ground.

. . . This does not need to be fixed anytime soon, it has been this way since I owned the van, almost a year, the turn signal only stays on if I do not straighten the wheel before I cut off the ignition, which is not often, however, I was wanting to button up the bottom of the dash and the plastic casing around the steering column, also, I do not like getting beat by anything, especially something that should logically be able to be figured out, electricity is logical, however, I also have to weigh what is practical, I would be content wiring in an additional relay somewhere to cut off the turn signal or whatever else is causing this issue, especially if repairing this is going to entail a large undertaking (wiring in a relay is what I thought I may have to do originally), seeing how this is 1998 van I am not looking for perfection, installing a relay would be fine. There are many other things that I need to repair on this van. I could also break off this for now and return to it later.

I am clueless here, I will continue to look over the wiring diagram(s). . . . .
I would not spend time looking at diagrams that have been posted in this continuing discussion of solving this turn signal issue. You need ACCURATE documentation that shows OEM factory wiring diagrams for a B1500 van, model year 1998. There are too many differences and types of devices used in the 1996 to 1998 time frame on trucks and vans such as electro-mechanical relays or solid state devices to try and make an educated guess as to the source of this problem.

I did a search on Ebay for a "1998 dodge b1500 van service manual" and found some OEM service manuals. Some very inexpensive and some priced over $100. If you want any chance to solve this problem then you will need some model year correct documentation to include wiring diagrams. Decision is yours.
 
#37 · (Edited)
I still have the multi-switch that came with the van, it was in pieces, the brake / turn / hazard contact strips were corroded, I was able to find the two screws that held it together and piece it together so I at least had brake lights so I could drive the van until I got a replacement multi-switch. I removed the replacement multi-switch yesterday and matched the wires against this old multi-switch, the wiring on both multi-switches are in the same location on the multi-switch and on both of the multi-switch connectors.

The turn / brake / hazard and wiper mode function switch appear to be two completely separated circuits within the multi-switch.

Maybe there is a wire(s) landed incorrectly on the other side of the multi-switch connectors in the main wiring harness or elsewhere.

I am clueless.
 
#39 · (Edited)
Yeah, I am at a loss, but then I am far from an expert.

Is the wiper circuitry, to include the delay circuit, typically powered by the ignition only, or does it also see batt + ?


Probably just take a break, work on other things and come back to this, may look at purchasing a service manual, not a priority at the moment however, may come in useful down the road.


Thank you for all of your assistance.

The good news is that the wipers seem to be moving faster after cleaning the copper grounding strap : )
 
#40 · (Edited)
. . . .Is the wiper circuitry, to include the delay circuit, typically powered by the ignition only, or does it also see batt + ? . . . .
All power for the wiper motor and associated circuitry flows through the RUN or ACCY position of the ignition switch. That is the reason the wipers do not park at the base of the windshield if you turn the wiper switch to the OFF position and then turn ignition switch to the OFF position before the wipers reach park at windshield base.

So to answer your question, the wiper motor only sees switched battery power, not continuous power. Depending upon the wiring layout, some component of the wiper circuitry could have continuous battery power. But a tracing of an accurate model year wiring diagram would be necessary to confirm or deny this theory.
 
#41 · (Edited)
Question :

Typically, on a vehicle of this year, how does the rear center brake light circuitry work without flashing and being independent of the other rear bulbs ? Does it work straight off the brake pedal switch without going through the flasher / turn signal switch ?
 
#42 ·
Question :

Typically, on a vehicle of this year, how does the rear center brake light circuitry work, without flashing and being independent of the other rear bulbs ? Does it work straight off the brake pedal switch without going through the flasher / turn signal switch ?
The third brake light is triggered directly from the brake switch signal (unlike the regular brake lights which go from the brake light switch through the turn signal switch so the signal flash overrides the brake light signal).
 
#44 · (Edited)
Here is another tidbit of information ... with the previously described issue, when I remove all of the fuses inside the fuse panel, only two fuses stop the turn signal from flashing if the ignition is off, the ' combo / flasher ' fuse, and the ' radio ' fuse. With the radio fuse installed doesn't matter if the radio is on, or off, same issue. With the radio fuse removed everything acts normal, the turn signal stops flashing once the ignition is turned to the OFF position.

As far as I can tell this looks like the original factory AM / FM radio, but I have no idea, and have not removed the radio to inspect the wiring. As previously stated, when I first got the van the radio (AM only) and clock (one small bar on the display) would work intermittently, then after a few months both the radio and clock worked all the time and still do (AM only), I figured maybe there was corrosion somewhere from sitting in the outbacks of Mississippi, or possibly a bad capacitor or something and it needed to be re-charged.

Does this mean I might be able to get my dash and steering column back together soon ?
 
#45 ·
. . . . when I remove all of the fuses inside the fuse panel, only two fuses stop the turn signal from flashing if the ignition is off, the ' combo / flasher ' fuse, and the ' radio ' fuse. With the radio fuse installed doesn't matter if the radio is on, or off, same issue. With the radio fuse removed everything acts normal, the turn signal stops flashing once the ignition is turned to the OFF position. . . . .
As state in post #38 you will need accurate vehicle wiring diagrams for model year correct B1500 vans to have any chance of resolving the strange turn signal behavior. You might find a Dodge B1500 van forum, join and post your turn signal issue and see if you get some responses.

. . . .As far as I can tell this looks like the original factory AM / FM radio, but I have no idea, and have not removed the radio to inspect the wiring. As previously stated, when I first got the van the radio (AM only) and clock (one small bar on the display) would work intermittently, then after a few months both the radio and clock worked all the time and still do (AM only), I figured maybe there was corrosion somewhere from sitting in the outbacks of Mississippi, or possibly a bad capacitor or something and it needed to be re-charged. . . . .
This radio problem might be a solder joint making intermittent connection on an internal component. No easy way to trace this problem.