Engine/Transmission (1994 - 1998) 97 electrical woes

[moser11]

OK. today when I started the truck the " wait to start" light didn't come on but the truck started... . the gauges were going crazy... . and when I put it into gear the OD button did not illuminate... . The truck started in 3rd and was real lazy... Grid heater was not switching off... volts were constant under 14



Question is with all this am I looking at a pcm/ecm??

unrelated but the day before my drl module packed it in...



Going to go through the cables and grounds but any other ideas ??

any help appreciated... . Thanks

 

[GAmes]

To troubleshoot the grid heater portion just pull the two small wires from the relays. Stock relays stick closed every now and then. There are several threads on replacing them with better quality units.



I have mine on a toggle switch. If I forget to turn them off I just get low voltage, then after awhile the pcm kicks the alternator off line. No other faults like you described.

 

[PatrickHansen]

Check your crank position sensor. The ECM needs the signal to 'know' the engine is running before the transmission, a/c, etc will be energized.

 

[moser11]

Thanks for the info... .

I did the cables and well ... . now I have new cables...

Still looking ... .

 

[JKosten]

Sounds like it could also be a bad ground. Not sure where but they can wreck havoc on electrical systems.

Good luck.

 

[moser11]

Just to update..... I managed to locate a prior prick test on the leads to the ESS. . which had caused slight wire degradation... so I fixed that and had a glimps of hope only to have it slip away..... actually I started up the ESS wiring harness and found after the connector but befor entering the main wiring loom a chafe on the cylinder head ,,,,,which fixed the problem..... So in essance the ESS ( engine speed sensor) really does effect a lot of unrelated operations when shorted to ground...



Thanks to the tdr... . search function and help