tcm question

[the.emilio08]

Does your car have any leaks? Do you notice any standing water in the ECU & TCU area after rain? The way you explain the light fading sounds like water shorting the board, causing the light to fade in and out.

It hasn't rained here in a while, and I haven't noticed any leaks into the interior or water around the ecu/tcu area.

[Ice D]

I am having a similar issue. Any progress?

[bobbycos]

I am having a similar issue. Any progress?

just had the solid S light come on while driving home tonite, bringing up these threads to see if any progress has been made instead of starting a new one

[madmattr6]

Have u jumped the blue connector and counted the flashes the "S" does??

[bobbycos]

Yeah the "S" light came back on. It worked fine for a few days after I pulled the ECU fuses. I know I jumped it right (on the old one) because the Check Engine light stayed illuminated after I bridged and turned the key to 2, but no "S" light. If I turn the key to 3 it turns it on and you're not supposed to do that. So I know it was done right. @Joshy, it had its normal shift pattern 1-2-3-4 when the light isn't on, but the "S" light came back on like I said even with the new (to me) TCU and it went back to limp mode. Sometimes it will be 1-3 other times it will be 2-4. I pulled it from the pick n pull off the same model car, but I guess the new one is bad too. Im gonna try jumping the codes again this weekend using the swapped TCU to see if I can get any codes from that one. There are times where the "S" light will be on for a minute and in limp mode, but then it turns off and shifts normal for the remainder of the drive. <--- this was today btw. Could it be clogged shift solenoids? Or would a code be thrown for that?

your new tcu is not bad

i replaced my tcu #28100-PX0-921 with a tcu that replaces the 922

worked fine day one, no S light then driving to work it would rev to 3500 rpm-20 mph to engage the shift from 1st to 2nd gear, then the rpms-speed would go to 3500-40mph to shift from 2nd to 3rd. top speed was 53 mph at 3400 rpm and the CEL would come on, got to work shut off to check codes and nothing! no codes

daheavyking said it could be shift solenoids so I traded for two brand new ones. haven't installed them yet but I talked to a guy who works at AAmco as a tranny rebuilder and he to me that 921 TCU's have to be replaced with another 921 or I will have the same problem

gotta dig in my hoard of old chevy parts to see what else I got to trade

[bobbycos]

Have u jumped the blue connector and counted the flashes the "S" does??

didn't need to, i could smell the bad tcu

[Hmong-cb7tuner]

where is the backup fuse? cant find it

[cloudasc]

where is the backup fuse? cant find it

Holy thread revival batman, glad you found the search feature of the site...

Anyways to answer your question, the backup/radio fuse is located in the fusebox under the hood.

Also anyone with tcu issues relating to this thread should check out the diy: tcu fix link in my signature.