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Discussion Starter #1
wondering about checking or replacing my PCM from my 2002 3500 van w/5.9l.

I believe my PCM is not working -getting a no start/no run - cut off when I was driving & has not started since them (was working fine before this happened)

I have replaced: cam position senor, crank position sensor, ignition coil, & ASD relay

I checked ALL fuses (in power dist. center & in fuse block inside vehicle) , fuel pump is working & there is power going to the coil, cam sensor, & crank sensor but no spark.

Is there a way to check to see if the PCM is bad? only check engine code is p1492-not sure what that is

Also if the PCM is bad are the PCMs interchangeable from yr to yr (ex 2003 w/5.2l or another yr w/5.2l or 5.9l) & if so what needs to be done to make it work on my vehicle? I was told that you need have have the VIN & mileage for it to work correctly.

I have only had the van for about 1 month & there is a sticker on the PCM that is was changed/and or reprogrammed 20k miles/ 3 yrs ago


Thanks in advance for any & all help!
 

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The PCM test is performed by making sure that all of its inputs: power, grounds and sensor/switch signals are present and that it's outputs to the relays, coil, injectors, etc are working. PCMs are usually the 'last house on the block' when testing for a 'no start' condition. Everything else, including wiring and connectors has to be ruled out first.
The coil and injectors are powered up (+) at 'key-on' and the PCM controls the ground (-) sides of them for both spark and fuel to the right cylinder at the right time.
A good OBD II code reader/scan tool should be able to tell you if the PCM is seeing these cam and crank signals.
If you lost gauges but the van still ran OK, then that may be a separate problem (like broken cluster solder joints or communications bus issues)? Has a 'no bus' message ever appeared in the odometer?
An 'Authorized Software Update' sticker is still your old PCM with new software: 80bbcfda.gif
Someone may have flashed it to try and remedy a problem. Possibly this current one? Reprogramming a PCM would probably not fix a 'no-start' issue.
The correct PCM part number for yours is 56040325AD for Federal emissions and 56040326AD for California emissions. Remanufactured PCMs would be R6040325AD and R6040326AD respectively.
P1492 is a battery temperature sensor (voltage high) code, and would not keep the engine from starting. The sensor itself may be broken or disconnected.
 

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This does appear to be a 2002 only part, specific to the 5.9 engine.
 

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Discussion Starter #4
there has never been a 'no bus' message on the odometer-for as long as I've had it
as for the sticker on the PCM it looks as if somebody reflashed it or got a reflashed PCM & installed it.
just trying to figure out why it would stop running while driving down the expressway & then not start-while getting power @ the sensors & relays (coil has power but no spark-like it is not getting the signal to send spark to dist.
thanks for the help if there is anything else that might be a cause for this please let me know as I'm running out of options
I will see about getting a good scan tool to try & figure this put
 

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Everything will have (+) power to it, the PCM controls and turns things like the coil and injectors on or off by providing the ground for them.
See if you can rent or borrow a scan tool. Go under the menu for the sensor display and see if the PCM is able to see the crank and cam signal.
If the tool cannot communicate with the PCM, the PCM may be in protection due to a short to ground in the sensor 5 volt supply circuit. This will prevent starting until the short is lifted and the key cycled off-on. Use OEM parts for replacement.
 

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Discussion Starter #7
I have new info

I checked with a scan tool & wasn't able to get any info about/from the PCM

I have removed the PCM from the vehicle & removed the cover from the PCM to find a spot just above the far right connector that appears to be a burnt spot (smells burnt & looks like it is 'oozing' & sticky)

Not sure how to attach a pic of the problem (if there is a way please let me know-thanks)

Please let me know what anybody thinks so I can possibly fix the problem
 

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Discussion Starter #8
how & what do I need to do to check the 5 volt supply circuit?

I have checked the crank position sensor connections & there is 5 volts there & the cam position sensor connections there is 5 volts there & I checked the coil connections & there is 10.2 volts when cranked on one side of the connection & 2.3 volts on the other side of the connection (these are steady readings-they don't change during cranking)

thanks again for the help
 

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If you have the 5 volts at the sensors, then your 5 volt supply sounds fine.
The negative side of the coil and injectors should change while cranking, but the change may be too fast for a digital meter to accurately display. The numbers will just jump around somewhere between 0 and 12 volts. It should never stay steady while cranking.
If you see and smell damage to the PCM, I would start looking for a replacement one.
 

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Discussion Starter #10
I was thinking that it might be that after checking the PCM and smelling a burnt wire smell in that area

I took the PCM out & turned the ignition key to on & then I got the 'no bus' in the odometer (normal -correct?) after reconnecting the PCM I got the odometer reading back

if any of this sounds wrong/incorrect please let me know

Thanks again for all the help!!
 

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I have a thread on here full of PCM troubleshooting. Search 00 ram van NoBus.
I listed everything I did, and links to more troubleshooting beyond that. 5v reference shooting, etc. From what I can tell, even jeep cherokees have the same wiring overall, so most should be right or at least similar on yours. A factory service manual set made a world of a difference though.
 

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Discussion Starter #12
Have new info-
I removed pcm from vehicle & sent to have repaired/rebuilt/reflashed (cost $139 + shipping) after getting back (about 10 days later) I installed the rebuilt/repaired PCM into the vehicle, making sure to remove the neg cable from the batt first, next I proceeded to try & start the van-when I tried starting the van it cranked but no start (I decided to recheck that I had all connections reconnected to the sensors as it had been wks since the start of the problem), all connections were connected, I tried cranking the van over again & noticed a burnt wire smell & noticed some smoke. I stopped the cranking & went to check where smoke was coming from (I had engine cover off inside of van & it looked like it was coming from front of vehicle) when I got to the front of the vehicle I noticed it was coming from the PCM right above the far drivers side connection (where I had noticed the burnt smell & saw the gel bubbled originally when I took the cover off the PCM before sending the PCM in for the rebuild)!
I'm still confused as to why/how this would happen?
I didn't experience this when it stopped running driving down the freeway as it took me several mins before I could look under the hood & by then if it was smoking it had stopped & whenever I have tried doing an diagnostics it has never done this.
If anyone has any ideas as to why or how this happened please let me know
I will talk to the company that rebuilt/repaired the PCM to see if they could explain it
PCM does have a lifetime warranty but I don't think it covers a fried PCM & I don't want & can't afford to buy a new PCM & have the same thing happen.

Thanks again for any & all help
 

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You need to do a PCM connector pinout voltage check. It sounds like you have 12 volts or ground on a pin where it shouldn't be. Probably when the ignition key is on for 12 volts. Do this with the PCM unplugged and with a test light.
You will want an engine compartment wiring diagram to trace wire colors. Has any wiring modifications or repairs been done?
 

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Discussion Starter #14
there hasn't been any wiring mods or repairs since I've had the van.
it was running fine right up to the time it cutout on the expressway-that is why it is confusing me (it acts like there is a short to ground or wires are shorting to each other to cause an excess voltage situation, but it hasn't caused a fuse to blow)
I will check the pin connectors & report the findings
it there a good place online that I can get the wiring diagrams?
thanks again for the help!
 

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I Googled and found nothing. Maybe a local main public library? Factory service manuals are factory copyrighted, so they are taken down soon after they are posted on the internet.
Other Dodge and Jeep trucks with this SBEC III(?) controller may have a similar pinout and wire colors.
 

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I believe what ultimately cooked my PCM was a coolant temp sensor that had internally fallen apart, possibly mixing 5V and gnd circuits to the PCM. Everything appeared fine, and it ran fine aside from random PCM stalls.Near the end of my troubleshooting, the coolant temp gauge died, when I went to unplug the sensor, it pulled in half from internal corrosion. Even if all your factory wiring is good, and everything works, a sensor or something could be intermittently shorting out and attacking the PCM. Slowly killed it before, fully degraded enough to cook it this time.

12V circuit seems more likely to burn things than small 5v reference, but still worth checking both before putting another PCM in.
 

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Discussion Starter #17
is it possible to use a PCM from another van (different yr-2000) as a 'tester' just to see if it will start or to see if I get that same smoking problem?
Will/should van start but get a 'code' stored if the PCM is from another vehicle?
Don't want to buy a new PCM & have the PCM fry out if there is a wiring issue that caused the original PCM to smoke.
Thanks for any help
 
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