This one has got me pretty confused, I will do my best to describe the issue, and what Ive done and tested so far.

Basic truck info:
1996 SLT, 5.2, 2wd, 90,000 miles (All original, other than typical part replacements over the years)

The engine turns over without issue, but fails to start. Was working about 4 weeks prior.

• No sounds from fuel pump
• Cluster lights, Buzzer sounds, Radio functions fine (Check engine light does not illuminate) the others do.
• AC blower functions on high setting (resistor at the firewall needs to be replaced)
• Pulled and checked all fuses in engine bay and under dash for continuity with multimeter
• Moved all relays to different locations
• Checked splice under PDC, still in perfect condition
• Attempted to check for any codes using the ignition on/off method.
  • No response, check engine light does not illuminate, not even a 12 or 55, nothing
• Attempted to read OBD using 2 different readers, both of which have previously worked for this truck.
  • Hardwired scanner receives power from port, but is not able to communicate with computer, link error
• Followed the troubleshooting writeup by Dodgerules86 here: LINK Results from that below:
  • Ignition off, ASD terminal 30 has voltage -good
  • Ignition on, ASD terminal 86 has voltage -good
  • Ignition on, ASD terminal 87 to injector connections DG/OR wire had continuity, yellow/white had no continuity (Injector 3)
• I have not yet checked for actual spark, need to convince a buddy to help out with that.

I dont mind going down the rabbit hole for this truck, Its my baby and I will do anything to keep it running, Lots of sentimental value. It is also not my daily driver, but previous to this it was still being driven 5-10/month sometimes more, sometimes less.

The thing that is really bugging me, and that is keeping me from dropping the tank and going head first into fuel pump/wiring at pump troubleshooting is the complete lack of response from the ignition DTC method, and the inability for both of my OBD readers to communicate with the computer of which both have previously worked on this truck, and continue to work on other vehicles. That is troubling me more than anything and could really use some guidance on what direction to go from here.

Thanks!

 

With the negative battery cable disconnected from the battery, disconnect/reconnect all three ECU connectors three or four times.

Reconnect the negative battery cable.

Due to my experience as an electronics tech, I'm convinced about 50% to 75% of the "Dead ECU" posts are ... due to oxidation on the contacts, which removing/reinstalling wipes the contacts and will serve to clean off the oxidation, "fixing" the problem.

And it's cheap, like free!

If it still won't talk to the ECU, I'd start checking the power at the ECU. Maybe bypass the ASD and the fuel relay at the pump, to see if it's a bad fuel pump relay.

RwP

 

Thanks, Will try that tomorrow and see what happens. Ive got a can of DeoxIT too so might shoot some of that in the connections to help make sure its as good as can get.

 

Hello Having exact same problem with mine let me know what you find out I've been checking wiring fuses relays splices grounds you name it even replaced parts fuel pump crank sensor on and on lol

 

If it's a 1996, have you asked the ECU what it thinks is going on?

RwP

 

Put a obd 2 scanner on it frist it said it could not connect after a few trys got it to read has no codes to show did same thing can not connect with 3 different scanners

 

Sounds like we're pretty much in the same boat, I couldn't get either of my scanners to communicate, no key fw/back code reading as well.

Working further on it today so far I've removed and reinserted the pcm connections multiple times and hit all 3 with some deoxit spray, no start. Put a inline spark tester in one of the plugs and got no indication. All 5 relays show between 75.6 and 76ohms across terminals 85 and 86.

When the key is moved from the ON, to RUN position the only relay click heard sounds like it is coming from the master cylinder. Nothing in the PDC makes any noise.

Will try to rig up a 12v battery and test the relays while energized and see what resistance they show next, then I guess I will pull the pcm again and look for power to the specific terminals according to the FSM.

 

Having gone thru this myself I sympathize with you fellas. I truly do. Keep your chins up.

 

I love the truck but I'm at the point to burn it or scrap it

 

Dakota only codes I can get is with key Turing 35 45