1996 RAM with a 5.9 liter MFI engine. I'm trying to help my neighbor fix her truck. Its located on an extremely remote island without services or mechanics, auto part stores, etc.

Short back story:

Driving the truck around it would randomly die every so often. This became slightly more freqent over time and finally it got to where it would not start back up. She had another one of the locals throw the parts cannon at it and he replaced the following:

Spark plugs
Wires
Coil
Distributor cap
Rotor
Distributor itself
Crank position sensor
Throttle position sensor
And lastly, the ECM

Zero change. I offered to take a look at it and did some basic googling. I tested for 12v at the coil wire with the ignition in run position, and found there was no power to it. I went back to the plug on the drivers side firewall and unplugged the harness, and tested for 12v there, thinking maybe the wire had a break in it somewhere. No power. All fuses good. Decided to swap around relays, and discovered the engine shutdown relay was faulty. Replaced it and checked the other relays. Confirmed all were good.

Truck started right up.... but during the five months it was down, the alternator pulley had seized. Shut it back off and then pipe wrenched the pulley and got it moving freely. Started truck back up, it ran for about five seconds and died. Was not getting any fuel, and found the large square #6 fuse had blown. #7 fuse seems to control trailer wiring, so I pulled that one out and put it in number 6. Tried to start the truck back up, and had fuel once again, but it would still not start. Coil wire was back to not having 12v power. Completely stumped here. I ran 12v straight to the plug and connected it to the coil wire with a jumper, and it still would not start.

Removed the harness plug again on the driver side firewall, and found the coil wire (green/orange) was now back feeding 6v. Yes, 6 volts. No idea why, what is wrong or what would cause this to happen. The lady doesn't care how jimmy rigged the fix is, she just wants her truck running again. Since the coil wire was back feeding at the plug on the firewall, I'm thinking there is some kind of electrical short, or some weird wiring issue happening somewhere in the harness. If I went to the coil itself, cut the power wire where it plugs in to the coil itself, and ran 12v from a switched electrical source, do you guys think this would work?

There is a red and white wire under the driver side dash that rats have chewed on pretty good. Any idea what this wire does? It runs outside to the wirewall and connects into another large harness plug right by the plug that containes the ignition coil wire.

Could a bad ignition switch somehow cause this? Truck is already rigged with a push button start. Any help diagnosing this issue would be appreciated.

 

On a 96 there is not much inside the cab that connects to the PCM, pretty much only the ignition switch provides "run" indication. There is another power feed directly from the PDC under the hood to the PCM for driving relays etc.. Here's what I would try: Make sure the power feed side of the auto shutdown relay doesn't drop out under load. Measure voltage with the relay removed and then jump the load terminals and check voltage while cranking. If it starts there is an issue with the relay control circuit (high resistance from corrosion e.g.) Also connect some sort of OBD2 tool and see if the PCM is responsive at all, or if it drops out during cranking. Are there any codes btw ?

 

They bypassed the ignition switch? Or just put the switch to crank the motor? Or a push button starter system????
You will only have positive power out of the asd rely for a short period without the motor running. The pcm will shut off the asd relay. The asd relay provides 12+ power to the coil/injectors etc. So you need power there for the truck to run. You can check codes using the key dance but if the ignition (key on/ignition) not working(push button start system) you cant test it. You will need to get a scanner.

 

The ignition still turns accessory power on, and the push button cranks the engine. That is the process to obtain codes via the key? The cluster does not have an electronic odometer, so I assume I would be counting check engine light flashses?

 

1996 is the 1st year of OBD2 for the Dodge Ram trucks. A dirt cheap Walmart scanner does a much better job of producing the codes instead of watching the light flashes in my humble opinion.

 

Nearest walmart is more than 1500 miles away and Amazon takes a month to deliver

 

You can order from Walmart.com and they will deliver it to you..

However, you don't say where you are located, in general, in your profile, so not sure if you are in the US, another country or orbiting the earth..

 

Near the end of the aleutians.

I was able to locate a code reader on the island... when I attempted to start the truck to read the live data while cranking, the truck started as normal. Unplugged code reader it died and would not restart. Plug code reader back in, starts and runs. I am guessing there is a short in the harness somewhere and the code reader is giving the ECM a ground perhaps? Not completely sure.

 

To do the key dance you need ignition on 3 times. Wonder if the push button start system is the issue? See if the pcm keeps supplying a ground to the asd relay. If the ground stays and engine still dies it's something else.

 

Wow! Thanks for clarifying the general location. Hope the weather is decent there to perform the repairs...