I'm getting a p0600 Serial Communication Link code on my son's car. I've replaced the brake sensor, Crankshaft Position Sensor and still the BAS Light comes on and then check engine light and his car gets stuck in first gear and won't shift out of it unless I clear the codes and it runs like a charm until it wants to do it again..which is becoming more frequently. I also have a little transmission fluid in the wiring the connects to the TCM sucking in through the wire from the trany. Didn't believe it till I saw it!!! Can I re-program my TCM? Also if the transmission fluid gets worse, any idea how to obtain a used harness that goes from the TCM to the Transmission or even what the name of that is even called? I can only find the engine harness on any search I do for THIS harness... Any help would be MUCH appreciated!!!!!

 

Basics first. Clean the battery ground at the frame. Check and reseat fuses. My limp mode & P600 issues were never the transmission. You've a communication error which is freaking out a module that controls/engages limp mode. The ABS module can do that. Perhaps others. Good Luck.

 

The first thing I would tackle is the leaking communication cable. The fluid can follow the cable and get in the TCU (research this site). Your problems may be related to fluid in the TCU and possibly low fluid level. If you are somewhat handy there lots of videos on youtube and many posts here about this topic. Needswings.com has the complete kit for transmission service. You could also find a local import mechanic to do this. If it was me I would also throw a new conductor plate while I had it apart, but they are $200 so many will not agree with this.

 

WRONG, the OP said he has fluid in the wiring harness... Nothing 'basic' will return this car to 'normal'. Although it is a good idea to suppliment/check the engine/battery grounds, this isn't going to help this member fix the car until his harness is replaced at the TCU and probably even a replacement TCU installed. THEN that connector at the transmission needs to be fixed BEFORE the car can be returned to service since it is allowing transmission fluit to 'wick up' the cable. Much more needing care here besides a 'phantom' grounding issue...


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hmm.. GraphiteGhost. Yeah..

I thought this owner looked familiar. Go read his post/issues with the car on 12-3-21. Now read his top post again. This dudes been randomly throwing parts at the car. None of which has corrected his issue. In fact, he had the transmission serviced/replaced the conductor plate - now he's got a leak. Well here's some good news: GraphiteGhost says you should fix that leak. How awesome is that?!

dude, your original problem is electrical and its not the transmission. I'll leave you here with GraphiteGhost. luck!