I looked at the wiring diagram for pins 37 and 57 and they come from the same source, the power out at the ECU relay. This wire then splits into, the power to activate the fuel pump relay, the WOT, injectors, tranny and IAC. You should have battery voltage at all of these and pins 37/57 with the key on. If one of these was shorting to ground you might get a voltage drop, did they try hooking a volt meter up to the circuit to see if the voltage is correct and constant when running.

 

I don't know, but i will stop by the shop tomorrow and ask and check on progress.


Michael

 

went by shop today...progress is still a head scratcher! watched technician as he hooked up engine scope to the wire from the computer going to the knock sensor and started the engine...signal coming from knock sensor was very noisy or out of pattern, tech said he has never known one to "cut out" but known them to retard the engine when knock happens, he checked all the grounds and everything is fine, the knock sensor was showing a spike on the scope also at different times when reving the engine....any opinions on knock sensors? can they cause an engine to jerk and buck if they are bad?

Michael

 

I never had one on any of my vehicles but I would bet a false reading could mess with the timing and other computer functions.

 

Truck is ready finally!!

shop called and they found the problem, it was a couple of bad wires in the wiring harness below the battery, the battery was leaning down hill towards the radiator and leaking acid on the harness which resulted in a shorting of wires, during accelaration these would touch just enough to kill power to the ecu relay or something he said...so i will pick it up tomorrow.


Michael

 

Glad to hear they found the problem, sounds like you found a good shop.

 

Yeah, as i said those guys are really skilled and they didn't want to give up until the problem was found...and thanks for all you who gave me input...i'll be back to this forum again when i have other issues, glad i can finally put this one to bed...thanks again.


Michael