1990 k5 Code 15 and 21 coming up

[Justin Fleming]

this is not ideal situation during a 30" snow fall right now....

 

[gmbellew]

"I think the ECM system has grounds on the front of the block by the thermostat housing and on the back of the block on the passenger side"

so these grounds would be like the master ground for the ECM? Does the ECM housing have a ground to the metal case? It appears that my ground at the thermostat housing is good, I would almost rather extend that to the battery.....

still trying to locate the ground on the passenger side back engine block....

those are the system ECM grounds, yes. the one on the back of the block is below the back of the valve cover on the passenger side.

 

[dyeager535]

And no, the ECM case is not grounded. All grounding is done through the two ECM connectors.

 

[gmbellew]

engine block ground braided wire is good and good ground, going to go drop the ECM down see what I can figure out there.

yeah, those pins I mentioned are the system grounds on my 1990. they should be grounded if you check at the ECM connector. next would be to check continuity/ground from the TPS/CTS pin to ground at the ECM.

 

[Justin Fleming]

So pulled the ECM out, testing all the ground wires for continuity and all ring out good. Put the thing back to gather and plowed for 1hr no issues...

at a loss....

 

[gmbellew]

So pulled the ECM out, testing all the ground wires for continuity and all ring out good. Put the thing back to gather and plowed for 1hr no issues...

at a loss....

if you did have 5v on both wires at the TPS before, I am not sure how you could have that unless the TPS was bad internally.

as a relatively cheap parts gun approach, replacing it might not be a bad idea. use an AC Delco.

 

[Justin Fleming]

I do believe the TPS was bad, and I have replaced it. I do believe I have a intermittent ground issue that is /was causing the issues as well....

Time will tell until the gremlin shows its head again...

 

[dyeager535]

Yep, I fought an intermittent code for quite awhile, randomly got lucky pulling the ECM connector out and noticed one of the wires moved more than it should. The lock tab on the terminal had failed.

 

[Wes Harden]

I have fixed numerous intermittent drivablity issues just by unplugging and reseating the ecm connectors. Was esp common on fords, EEC IV. Has worked on gm too.