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Help with OBD I TDCO Setting

I take it you have GMTDScanTech.

Years ago I got code 88, I ordered that program. I programmed a relearn. Then TDCOffset, for about 60 seconds I was crapping my pants.

Welcome to the club, you're in for a ride. :)
 
Check the resistor in the PMD connector. it's ether gone bad or it's missing and the PCM is looking for it to calibrate the IP. once you can get rid of that code you can do the relearn for the TDC offset
 
dbrannon79 said:
Check the resistor in the PMD connector. it's ether gone bad or it's missing and the PCM is looking for it to calibrate the IP. once you can get rid of that code you can do the relearn for the TDC offset
Click to expand...

Is the resistor on the harness side or in the PMD side of the plug connection? If we need new, what # Resistor do we need? Where do we get it?
 
I'm not sure if there's different qualities of resistors.

I think they may even have been available at AutoZone.

Leroydiesel.com and John Faddis are always trusted sources.

My resistors we're always in the PMD. #5 is fine. I don't think a #9 hurts anything
 
the resistor should be located on the inside of the connector on the PMD. here is a pic of where it goes. a #5 should be fine, that is what is in mine. I'll dig up the part number here in a bit, you can get them from most of the auto parts houses in a kit with a #5 and #9.

1649772418142.png
 
get it up to operating temp and run the relearn. on GMTDscan you will need to do the timing set first and make sure it reads as close to 3.5 as possible. if it's too far off youll need to tweak the IP slightly one way or the other. the last time I did this I had loosened all three nuts on the IP and left the top one snug enough that I could run the engine and still bump the IP a smig. then did the time set again watching the actual IP timing, bumped it till I got it as close as I could to 3.5. afterwards ran the relearn.
 
when you pull up the screen for the relearn there are three readings (or two) shown on the screen. what are those reading currently without clicking on the set or learn buttons?
 
the truck has MrMarty's IP on it? if you already ran the TCD learn then and it was all good. I'm curious what might have made it change and set the code. only things that come to mind is the IP came loose or the stepper motor in the IP having a fit.
 
dbrannon79 said:
the truck has MrMarty's IP on it? if you already ran the TCD learn then and it was all good. I'm curious what might have made it change and set the code. only things that come to mind is the IP came loose or the stepper motor in the IP having a fit.
Click to expand...

Yes, Marty's IP is in it. He never ran the TDCO learn. Just threw in the IP and ran it for about 300 miles and started getting codes. He had dropped the Eng Motors cable into the box with my Tech 2 which I took up to Montana to do tests on the Transfer case on my '99. We mailed the cord back down to him, so now he's working on it. Then he tried the TDCO learn and got the screen I posted to start this thread. He changed PMD and that eliminated the resistor code, so he's down to TDCO learn.
 
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ok, so I think he will need to loosen the IP and set the timing. it's prob slightly off, just enough to set the code. I don't think it being slightly off will hurt things running it but I would let others chime in to verify that. I think it would depend on what the actual IP timing reading is showing. he might try just running the relearn and see if it lands at an acceptable number.
 
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