Hey everyone, (truck is listed in signature) I just finished a long overdue rebuild on my transmission, so everything mechanically is good. The 2 codes being thrown (1765 and 0753) were popping up prior to the rebuild and I did swap solenoids a couple times prior to the rebuild to see if that was going to clear the problem... it didn't. During the rebuild I did install all Rostra electronics among some other upgrades, and it seems to run rather well until the PCM kicks those codes, then it intermittently will not want to give me 1st gear, or it may shift inconsistently. I did check and adjust the TV cable, and replaced the transmission control relay. I also checked for voltage at the 12V and 5V pins on the harness going into the transmission. The only thing that struck me as odd there was that I had 6.2VDC on the 5VDC pin, but I'm assuming that's not a serious issue.

So, now my question is do I use this info that I found (for a cummins, not a gas engine) HERE and test the circuit as described in that article, or jump out that pink wire to ground and see if the codes come back?

Thanks for the advice and input in advance!

 

Trans works the exact same way, so, that procedure should work. If you don't have one already, grab the service manual for your truck from here.

Also, look at the wires going into the 8 pin connector down at the trans. They like to pull out some, and then short together.

 

Awesome! Thank you. I kinda figured it would be the same, but I wasn’t 100% sure. I also appreciate the heads up on that connector, I’ll definitely check it. I already have the FSM, (got it here lol), thank you again!

 

P1765 Trans 12 Volt Supply Relay Control Circuit
If you don't find an issue with the plug/wires may want to swap out the relay.

 

Did that already, twice. Plus is have a tool that will test relays and they have all tested good. I have a bad feeling it's going to be in the PCM but I want to eliminate all other possibilities first. That stupid PCM has been repaired twice in the 12 or so years I've had the truck, both times for a faulty voltage regulator.

 

I wanted to update this thread in case someone else can benefit from it. Sorry it took so long, I've been busy and haven't had a chance to really relax. After doing a lot of troubleshooting and ignoring the link I posted originally, I found that I had continuity with no abnormal resistance on the wiring. I checked all pin connectors and made sure nothing was loose or backing out. I not only tested the relay with my power probe and the relay testing attachment, I also swapped the relay just to be absolutely certain. I then went to YouTube where I found a couple of videos that were helpful in confirming my suspicions that it was a bad PCM. The one I shared shows how to verify that you are in fact getting power to the switch leg of the relay. The other video I watched wasn't something I feel comfortable sharing because the work was, lets just say not the best lol. But it did point me in the right direction. There is a pink wire going to the PCM on C2 Pin 30 (there is a link above here in the feed for the Factory Service Manual or FSM) that will help you if needed. I spliced that wire and added a leg going to ground, so I essentially have a 3 way splice, and that has eliminated the issues with shifting and throwing the P1765 and P0753 codes. Now I just have to get the PCM repaired or replaced.