I am new member and not real familiar with site but got to FAQ but unable to find diagram or service manual. I tried both library links but they didn't work. Wiring from ignition sw. to relays checks OK. Power to PCM on dark blue wire as well as red/wht. checks. Blue/yel. wire from common side of relays to PCM OK. Rain forced work stop. Have found no other splices. Still need to check green/orange from relay contacts to PCM. How does the check engine light relate to the problem? I am grateful for the help - want to check everything I can - but it is looking like maybe a bad PCM???? Someone on the forum mentioned changing ECU for a similar problem. What is ECU?

 

OK - could find no more splices. Checked wiring: ignition sw. to both relays OK 12v on dk.bl wire with key on. Red/wht. wire to both relays and PCM OK 12v always hot from fuse. Dk.blu/yel wire from both relay coils common to PCM OK. Dk. green/orange wire from ASD relay to PCM OK. Anyone know how the check engine light is related to this problem? It must be internal to PCM??? or not?? Without this light on with key on truck won't start. I have run out of ideas on what to try next. I appreciate any ideas or suggestions. Thank you - I need to get this truck running.

 

The FAQ is just a few posts above this one. On the left hand side of the page there is a green arrow pointing to it. You can download the FULL service manual from there, which includes wiring diagrams.

The ECU(Electrical Control Unit) is the PCM(Power Control Module) which is the computer.

And again the ASD relay activates the computer. The computer turns on the check engine light. So if the computer has no power, guess what no check engine light.

 

Crazy 4X4 & Skyshark186 - Thanks guys for all the advice, etc. I have learned alot from all this. I managed to get the service manual for a '95 and some diagrams for a '94 which are close but not exact. Thank you for pointing out the links. It took a while but late at night I was able to download them. Apparently there were some significant changes from '93 i.e. fuel filter inside frame and not part of fuel pump module. Fuel pressure regulator not in throttle body and not in fuel tank module but at rear of fuel rail on left side. Thought you would like to know that the PCM was bad. The power to the fuel pump relay, ASD relay, and check engine light are from the power distribution center inside the fender on left side. The ground for each of these is through the PCM so all the relay chattering and intermittent operation was due to the PCM failing. I had to search all over the area but finally found a used one today, installed it and everything works great once again. Getting the diagrams and service manual made it all come together. Thanks again. I traced and reworked at least 6-7 splices in the process so perhaps headed off future problems.

 

Cool! Glad you got it!