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1985 W150, 4x4 360 Truck. Truck will start and run for about 2 seconds then die.,,,, Plenty of gas and fire. Plugs, wires, cap, rotor, voltage reg, ignition module, coil, resistor all néw. I swapped out coil, cap, starter relay, ignition module, and resistor just to see if they might be faulty. My final attempt I ran a hot wire from the +coil to the +battery, starts fine, runs fine. Best research I’ve found was that it’s a relay switch. Any opinions or suggestions?
 

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This is the part that keeps popping up in my search. Sound right to you guys? Anyway to check these out, or is the hot wire the test?
 

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I had similar problems with my 74-80 pickups and a couple of times, I had purchased both resistors and ignition boxes at a "cheap" parts store only to have them fail out of the box. Finally went to the NAPA store and bought their ECHLIN brand. Had no problems after. (Did carry around spares for years after) Of course these failures came on my jobsites 30 to 80 miles from nearest auto parts stores. Hope this helps.
 

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. . . 1985 W150, 4x4 360 Truck. Truck will start and run for about 2 seconds then die.,,,, Plenty of gas and fire. Plugs, wires, cap, rotor, voltage reg, ignition module, coil, resistor all néw. I swapped out coil, cap, starter relay, ignition module, and resistor just to see if they might be faulty. My final attempt I ran a hot wire from the +coil to the +battery, starts fine, runs fine. . . .
You turn the ignition key switch to the START position, starter engages, the engine crankshaft turns and engine fires and runs. You release the key switch to return to the ON / RUN position and engine dies. This is classic example of a ballast resistor that has failed; not passing reduced voltage (less than 12 V) to coil. You confirmed the ballast resistor failure by wiring directly to coil and engine runs.

Since you replaced the ballast resistor, there might be a wiring problem at the resistor. One side of the resistor should have 12 volts with ignition key switch in the ON / RUN position and the opposite side terminal voltage less than 12 V that then travels to the ignition coil. See attached image.

Also check to see if your vehicle has the dual pickup relay. The dual pickup relay switched electrical current between 2 different sensing elements in the distributor. For starting one sensing pickup was retarded for engine starting. When the engine started and the starter relay de-energized, the relay switched power to the RUN sensing pickup with more base timing advanced. The dual distributor pickup with dual pickup relay was used only on engines with lean burn spark advance control.

Starter Ignition Distributor Wiring.gif
 

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You turn the ignition key switch to the START position, starter engages, the engine crankshaft turns and engine fires and runs. You release the key switch to return to the ON / RUN position and engine dies. This is classic example of a ballast resistor that has failed; not passing reduced voltage (less than 12 V) to coil. You confirmed the ballast resistor failure by wiring directly to coil and engine runs.

Since you replaced the ballast resistor, there might be a wiring problem at the resistor. One side of the resistor should have 12 volts with ignition key switch in the ON / RUN position and the opposite side terminal voltage less than 12 V that then travels to the ignition coil. See attached image.

Also check to see if your vehicle has the dual pickup relay. The dual pickup relay switched electrical current between 2 different sensing elements in the distributor. For starting one sensing pickup was retarded for engine starting. When the engine started and the starter relay de-energized, the relay switched power to the RUN sensing pickup with more base timing advanced. The dual distributor pickup with dual pickup relay was used only on engines with lean burn spark advance control.

View attachment 79381
Yes it has the dual pickup distributor. This was the only thing I didn’t retry. I’m prettty certain it’s not the resistor on the firewall. I’ve got another distributor from summit I bought years ago, aftermarket. Will I be ok to drive the truck hot wired so long as I unhook the wire when I’m done? Waiting for warmth here, it’s 10 degrees.
 

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Yes it has the dual pickup distributor. This was the only thing I didn’t retry. I’m prettty certain it’s not the resistor on the firewall. I’ve got another distributor from summit I bought years ago, aftermarket. Will I be ok to drive the truck hot wired so long as I unhook the wire when I’m done? Waiting for warmth here before I change it out,,, it’s 10 degrees.
 

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My Dad's '84 RAM exhibited those exact symptoms with the field coil in the alternator shorted out. The alternator is not part of the start circuit.
 

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. . . Yes it has the dual pickup distributor. This was the only thing I didn’t retry. I’m prettty certain it’s not the resistor on the firewall. . . .
You will need to perform some voltage tests at the ballast resistor to confirm it is operating properly. But I understand you want to postpone any extensive testing because of outdoor weather conditions.

. . . Will I be ok to drive the truck hot wired so long as I unhook the wire when I’m done? . . .
"hot wiring" the coil as you mentioned will get the engine to run. The problem is that you are applying full 12 volts to the electronic control unit and distributor pickup. Chrysler engineers were concerned that full voltage supply over an extended period of time might cause the electronic circuitry to fail due to excessive current flow. So that is why the ballast resistor which reduces electrical current to this electronic circuitry was used. You can bypass wire it as you describe but you run the risk of causing the circuitry to suddenly fail and your vehicle will stall.
 

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Can't you simply remove the jumper wire to the coil and have the truck still run? It's been years since I hot wired one this way, along with gallons of beer and two brain surgeries. I can't remember if removing the wire caused the engine to die or not, but don't THINK so.
 
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To verify the ballast resistor isn't the problem, run a wire across the two sides to jumper and essentially bypass it, but don't run it longer than about five seconds. Too much voltage will cause hall effect issues and burn them out, but a test like this will be OK. Otherwise it could be in the wiring after the ignition starts the engine and powers through the ballast resistor.
 
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Can't you simply remove the jumper wire to the coil and have the truck still run? It's been years since I hot wired one this way, along with gallons of beer and two brain surgeries. I can't remember if removing the wire caused the engine to die or not, but don't THINK so.
No it dies immediately
 

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Did
To verify the ballast resistor isn't the problem, run a wire across the two sides to jumper and essentially bypass it, but don't run it longer than about five seconds. Too much voltage will cause hall effect issues and burn them out, but a test like this will be OK. Otherwise it could be in the wiring after the ignition starts the engine and powers through the ballast resistor.
It turns out it was the resistor. Barely moved it and truck die. Put a new one on, removed the jumper wire, starts right up.
 

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It turns out it was the resistor. Barely moved it and truck would die. Put a new one on, removed the jumper wire, starts right up. So glad I didn’t have to replace the distributor. But I May have a new problem. The lights were going dim up and down as speeds lowered or accelerated. Changed out the voltage regulator and it stopped. Went to start the truck this morning and it barely turned over like something had drained it. I’m figuring I’ve got a short somewhere. Maybe that’s why these two parts had issues. The truck is an 85, very little rust, only 88,000 miles well taken care of , but the wires under the hood are brittle and cracked in so many places. I’ve had 5 of these styles including a Ramcharger. They seem to be notorious for wire issues after 25+ years. Do they make a quality aftermarket harnesss to run everything I need. The truck was fully loaded so there’s that many more wires. The air doesn’t work nor does the cruise, not really worried about that. Any ideas on upgrading the wires? Personal experience.
 

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I doubt it's a short, but an current draw that is the problem.
First step would be to ensure you have a good battery and a healthy charging system.
Then you can measure the current draw and remove fuses until it's gone. then you know which circuit has the problem and work from there.

A replacement wiring harness will be a junkyard item.
 
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I doubt it's a short, but an current draw that is the problem.
First step would be to ensure you have a good battery and a healthy charging system.
Then you can measure the current draw and remove fuses until it's gone. then you know which circuit has the problem and work from there.

A replacement wiring harness will be a junkyard item.
the battery was perfect till this morning. Interstate brand. It’s been colder than normal and I’ve had the block heater on. But it barely turned over. After it warmed up I shut it off, and it seemed to have charged. Quick start. I went inside and let it finish warming up, about 15 mins. Turned it off and this time it acted as before. Barely cranked. Mystery to me. Ran out of time to do more checks. Try again this afternoon
 

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My experience is, when a good battery dies that quickly and badly, there is a shorted diode in the alternator. You can test by starting it and checking the voltage at the battery while idling. If it's around 13.3 volts instead of 14, it's a diode. Temporarily you can disconnect the battery overnight until you get a new alternator. But confirm that's it before buying a new one.
 

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You might want to check the bulkhead connector for corrosion. It can happen.
 
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the battery was perfect till this morning. Interstate brand. It’s been colder than normal and I’ve had the block heater on. But it barely turned over. After it warmed up I shut it off, and it seemed to have charged. Quick start. I went inside and let it finish warming up, about 15 mins. Turned it off and this time it acted as before. Barely cranked. Mystery to me. Ran out of time to do more checks. Try again this afternoon
Check all you ground connections as well as the bulkhead connections. 60-70-80's Chrysler products are noted for bad grounds (usually corrosion issues) Check all ground connections not just the battery cable.
 

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My experience is, when a good battery dies that quickly and badly, there is a shorted diode in the alternator. You can test by starting it and checking the voltage at the battery while idling. If it's around 13.3 volts instead of 14, it's a diode. Temporarily you can disconnect the battery overnight until you get a new alternator. But confirm that's it before buying a new one.
Do you think by me replacing the bad voltage regulator it allowed the bad alternator to drain my battery? It’s been solid cold digits all week and last, this is the only time the battery let me down. prior to this is when I had dimming lights, hot wire to the battery, and for some reason my heater motor fuse kept blowing. All those issues went away when I replaced the resistor and voltage regulator, now for whatever reason the battery is dead. I’ve got a spare alternator to try. I’ve got spare parts for just about all of it. I’ve added extra grounds from the motor to the firewall. I learned that years ago. And when I put the voltage regulator on I brushed all surfaces.
 
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