Hello - I have a 1998 Dodge Ram 1500 5.9 360ci 4x4 Automatic Trans w/4x4 floor stick.

I have No Spark and No fuel prime/run. The Fuel and Asd relays are Good and... when I jump the relays (87&30) I have 12 volts at coil/efi and fuel pump runs constantly. I have changed the distributor cap, cam sensor, crank sensor.I havetried unplugging crank sensor,cam sensor,tps, speed sensor and each O2 sensor whileclearing the computer each time and still no response when you turn key to on at asd or fuel relays when key is turned on no clicking. there is 12volts at the relay and key.provides additional 12volt terminal so relays have proper power. Checked harness. and grounds and connector for obvious problem. The check engine light comes on for a few seconds and goes out when you turn the key on. Using a generic scanner it had one asd code. It has!good compression and only 120,000 miles.

what I haven't tried yet is disconnecting the trans to rule out an internal short to the shift solenoids. I also have not verified 5volt to TPS or map (?) But was planning that as my next shot.

me and a friend with meter tested the wires from the pcm connectors to their source and no open short/ground there.. I am pretty sure it is not the PCM, or hoping its not... but I suspect a ground to the pcm or a chaffed wire. maybe a mouse got hungry and ate some wires .???

I HAVE NO POWER AT THE "OXYGEN SSR" Fuse in the pdc (power distribution center) under the hood where relays are. Its. a 15amp. I can't remember if that's normal or if it has power after running?? But no power on either side fuse good

Anyways i got it non running in a trade and need this truck for a driver its been sitting for weeks at a friends house 50miles away so i want to know what else to try on my third attempt.
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I know this is a common worst case scenario electrical problems these trucks have but I can't seem to find any solutions I might have bypassed. I am a former Daimler Chrysler 5star ServieManager. and ASE Mastertech/Auto Machinist so I have pretty much done everything I could except swap computer. I was also to it was running a litle funny before it wouldn't restart at all.

I guess what I want is info about oxygen 15amp fuse in pdc & How to make sure my PCM. is grounded properly & what i should be looking for with a meter at the pcm harness with key on and off...

 

Fuse K (O2 sensor) gets power feed from ASD relay.

Need to find out why PCM isn't controlling the ASD.

If you jumper ASD, will fuel pump run? Will the engine start? What's missing if it won't?

 

If i jump the asd i get 12volts to coil and at efi - the fuel pump only runs if I jumper the fuel relay

it wont start with asd and fuel jumped because even though I get 12volts at the coil I still have NO spark

it has a new cam and crank sensor

 

Verify you are getting 5 volts to the cam, and crank sensors. With the key on, they will always have power. (provided the battery does. )

 

Am I supposed to have 5volts at the TPS? Or any other sensors on the engine ? I have not disconnected the transmissions harness yet to isolate the problem.

And what should I do or assume if I do not have 5volts?

 

The various sensors, TPS, MAP, Cam, and Crank, (and possibly O2 sensors, temp sensor, etc) should all have 5 volts (or a little more) with the key on. If you don't already have a wiring diagram, grab the 01 service manual from the Service Manual thread in the FAQ section here. It will be pretty close to yours. (pin positions should be correct, wire colors may not be.....)

All those sensors get their power directly from the PCM. If one or more of them do NOT have power, and you can find no breaks in the wires. Bad PCM.

 

But what IF.the pcm is in shutdown mode (considering the asd code pulled)

I've pretty much eliminated everything but the map and temp sensor and trans solenoids then. not a good sign ..... i don't really expect either to be the culprit. I expect the issue to be in the wiring - the truck was rode hard in the mud before it had a problem

how do i make sure the pcm has a good ground?

 

I am using my Android phone to get on the Internet. In the tools/ tsb-recall section I cannot choose my year/model/make/engine for some reason after many attempts.

I was wondering if there was a TSB for my symptoms?

I know this is not the first time this has happend to a ram for a fact

 

Check all the connectors at the PCM. I think the case grounds to the firewall via the bolts holding it there. (there *might* be a wire, but, I just can't remember....)

If you don't even get pump prime when you first turn the key, it would have to be a hard failure for the PCM to not even trigger the ASD relay. If that's the case, it should be too hard to find. (as these things go......) But, if the PCM communicates, not sure it will be a ground issue AT the PCM......

 

Well that make sense.

I guess the thing was hard to start sometimes and ran a little rough, then wouldnt run, then started one day and ran beautiful and then never restarted.

I did notice the miles in the digital odometer display were flashing/blinking and the check engine light came on for only a second and went out when I turned the key to on/run and I don't know if that's normal ...

I read many many forum posts everywhere I could about this issue and there were a few solutions that included grounding the pcm property but never a description of how. Most of the time there was never a solution posted or any help so thanks for your time