Posted about this before and didn’t get anywhere so here’s to a second chance!

99 Ram with auto tranny stuck in limp mode. The code was intermittent for awhile, usually if I let it sit for a couple weeks and start it up it’ll have the P0753 and I clear it and it never came back unless I let the truck sit.

Now the code was not getting erased so I replaced the shift solenoid and unfortunately it was still doing it giving me the P0753. After I cleared the codes again and was hoping it’ll go away…the P0753 went away and now it’s showing a P1765! At one point I did get all of these codes but never got them again


The relay for the transmission is clicking as fast as a machine gun when the key is on but not running. Any help would be appreciated, I’m at a loss!

 

try swapping the trans relay with the horn relay or similar in the fuse panel.

 

should’ve stated I did that already, but no change

 

Well with the TCC code I would almost guarantee you have an issue on the 12v supply circuit, or bad ground from the engine , but i would expect more engine circuit related codes if that were the case. Might need to load test the circuit.

 

Man it sounds like you’re speaking a different language lol I’m terrible with wiring, it’s my kryptonite unfortunately

 

So 0753 and 0743 are electrical circuit codes. This quite often indicated an issue with electrical circuit instead of the actual component. The trans is supplied 12v via the relay (issue more confirmed by the 1765 code) and the ground circuit of the solenoids is controlled by the PCM to activate the solenoids. It wouldn't hurt to check the body grounds by the PCM.

 

I cleaned all of the grounding points for the pcm and nothing changed also. Does the relay going off like a machine gun insinuate that there is a short somewhere? Somebody told me previously that this could be a alternator issue because the same circuit is on the alternator?

 

If the relay is chattering, there is a problem somewhere there. Generally that indicates low voltage on the control circuit.

 

Failing alternators can cause some strange results, it wouldn't be a waste of time to disconnect the field windings and battery lug and take a short drive to see if codes go away. Note the GEN light will be on but this is no bother for a short time.

I believe the solenoids are PWM so A/C voltage running down the line could definitely cause some strange results

 

isnt the black wire once the terminal on the alternator suppose to be positive? I know it’s black cable but I could’ve sworn I read somewhere it’s still positive cable. I have it in the negative battery post though but I think I always have?