Hi Everyone

When driving (in town or highway speeds), the truck randomly dies and then becomes a crank, no start situation but eventually starts and runs fine until the next crank, no start. Occasionally, it will have a P1389 and have seen No BuS at the mileage display area. When it is running, it seems to run fine (and no codes shown). I thought I had this solved when I could tilt the ASD relay one way, it would die idling; then could tilt it the other way and it would stay running (the relay would click and the fuel pump would run). I pulled the relay, disconnected the battery, and sprayed QD Electronics Cleaning on the relay connections. I then used a pick to gently bend the blade connectors in for a tighter fit. I replaced the relay and could feel a more solid connection. I also replaced the IAC and that didn't change the situation. Just before the issue arose, I recently had the AC compressor, blower motor resistor, and ABS module replaced. Not sure those updates are related, only to say that it upset the "delicate balance" of the system.

Also, I sat with the truck idling and tried wiggling the harness and pushing on the PCM connectors. Nothing, happened, I walked away then the truck died (so not sure if it died from that). The truck magically was able to start, as it does after a few on/off cranking. When it does not fire off, the fuel pump motor cannot be heard running. When I hear the fuel pump, it always starts back up. I am going to try replacing the crankshaft position sensor today. My other parts cannon move will be to replace the ignition coil, then the PCM.

I have read posts about testing wires but don't know what to test and would like ideas before I buy a PCM. Seems like a voltage issue to the PCM or at the PCM.

Thanks in advance!

 

Code is (P1389 No ASD Relay Ouput Voltage at PCM) and from your description it would make scene. You need to see if you have constant voltage(relay output) when running. The asd relay supplies power to the coil,02's and injectors. With out power it doesn't run. Check voltage a the ignition coil positive and battery negative, Then wiggle the asd relay. If the voltage cuts out you still have an issue.

 

How do I check the voltage at the ignition coil positive? I thought this was fed from the distributor. I am pretty confident in the connection at the PDC now after adjusting the blade connectors. Next step is to change the crankshaft position sensor, then the ignition coil. I know after it has died, key off, then key on (not in crank), I won't hear the fuel pump, and consequently it will not fire. After a few cranks, the pump comes back and then it does fire and runs normally.

 

Crank sensor or coil won't fix that. You have a asd relay issue. It supplies power to the coil, and the fuel injectors......

 

HeyYou - OK. I have replaced the relay, cleaned and tightened the connection. I am seeing voltage at the PDC connection. What do you suggest I check?

 

Does it still do the same thing? If it does, check the connections for the power source for the relay, the ground connection at the PCM, and also the power feed to pin 86, (which should be from the ignition switch.... I think.....) Also, try simply swapping it with the horn relay, see if anything changes.

 

Thank you. I am driving waiting for the next occurrence, so just reporting in. Adding this here to summarize what has gone on. When this first happened, I swapped the ASD relay with the AC relay and it started. I went and bought a new relay and after a bit it died again. We wait, we crank a few times, and we are back up and running until the next time it dies. After doing the following, I have not had it die yet, I am still testing it out on the road:

• Checked the ASD relay: constant voltage OK, key on voltage OK, wire to pin 3 to relay ground is 0.1 Ohms
• QD Electronics Cleaned the PCM connections
• Cleaned the PCM ground strap to frame
• Cleaned the top and underside of the PDC
• replaced the crank position sensor
• replaced the IAC
• replaced the ignition coil