Resister Code 56 experiences?

[Crankme69]

The Tahoe made it home 600+ miles, 1st tank wrung out 20.4mpg running 75ish mph on the expressway with gusting 50mph crosswind. I am very pleased. The drive home in the wind was less then desirable, to say the least. Bambi tried to end my Tahoe 20 miles away from the cabin, had all 4 wheels locked up, the anti lock works great.

Barry yr help & hospitality was exemplary...I am very grateful :thumbsup: :tiphat

How many of you have ever battled code 56 resistor error? I am thinking grounds or maybe a wiring issue? The wire loom is suspect as Barry & I found that moving the loom about & checking the PCM harness plugs allowed us to clear a pedal position voltage code before I departed from his shop...

Tonight I tried my known good spare PMD that has # 9 resister in it, no luck there. I also swapped PCM's & was able to clear the code until I shut the truck down & bingo it's back & I can not get it to clear...also tried running the TDCO learn & set options with my GMTD scan, still NO love. :nonod:

Please share with me yr thoughts with this 56 resister error code...

I ran this truck home the 600 miles with this code 56 & checked for any other codes after I got home (no other codes but 56 present or in history) I was hoping the pump mounted PMD maybe an old Kennedy #13 resister in it, or no resister at all but that don't add up after tonight's experiences...

 

[buddy]

Only battled this code when really messing with the PCM I could cause it to erase this memory location by making the PCM read bad data and stall and it would happen. But I would remedy it right away with the TDCO learn.

The resistor is across pins D and E of the PMD, D is the ignition power source, and E goes back to the PCM pin C2 of the 24 pin pink connector. It could be that between pin E of the PMD and pin C2 of the PCM there is a short to ground or power. You can disconnect both ends and check resistance between the PMD connector pins. You can test the voltage at pin D with the igntion on it should be battery voltage. If its low it may read the resistance out of a range that is recognized.

Diagram of the wires is on page 2 of attached
View attachment PCM-FSD-IP signals.pdf

 

[bk95td]

I think someone needs to update their signature

 

[Crankme69]

I think someone needs to update their signature

Done!

 

[Crankme69]

Ok I got it...guess I had 2 bad resistors all codes are clear...adjusted the pump TDCO now set at -1.85

Have not taken it out for a test run yet, but it sure is starting better.

Found a K47 air box to install at local junk yard for $70 bucs, have to pick that up tomorrow morning. Still have what I think is too low voltage at idle 12.6ish, that is about 1 full volt lower then my 1500...got more work to do there.

Bunch of little things that need attention just glad that the code 56 is history :thumbsup:

 

[btfarm]

Lookin' forward to seeing it Greg. Maybe we need to have a lunch sometime around Christmas week or something.

 

[Crankme69]

That sounds like a plan Mike!