Limp mode and alternator trouble -leaking cap in TCU

DSMcamaro · 12-03-2007, 12:06 AM

92 Turbo AWD Automatic......
After a large amount of snow over the weekend, I was driving my car and all of a sudden my lights started to dim and my wipers started to slow down. I knew it was sign of low voltage so I pulled over in a parking lot so I was off the street. While in the parking lot a proceed to rev it up to try and keep the alternator pumping out some volts. I could hear the belt squeal a couple times on and off while driving. Somehow, after that scare, the car seemed to be ok. The next day I decided to tightened up the alternator belt and do some other maintenance to the car. I also check the voltage and i was only seeing 12.6 volts at the battery and 12.8 at the alternator while the car was idling. I've never really had and alternator give signs of failure before. Usually they just die on me. Now the car is in limp mode.

1) Would a bad/weak alternator cause my transmission to go in limp mode?

2) Is it ok to drive in limp mode?

3) Whats an acceptable voltage? 13.6 and higher?

4) Are the alternators for a Automatic different from a Manual?(turbo awd terms)

I will be checking the TCU tomorrow a long with all the fuses and possibly be reading the codes with a multimeter.

DSMcamaro · 12-04-2007, 04:17 PM

Is this fixable?

1gDSM4g63 · 12-04-2007, 04:25 PM

Yes, it would be best to go to a professional, DSM (Talon Eclipse Laser) and 3S (3000GT and Stealth) ECU Service and Repair, and replace the capacitor and do some resoldering.

DSMcamaro · 12-07-2007, 01:44 PM

A new TCU fixed my limp mode problem. My alternator had a bad dieod. And to answer my own question, The automatic tranny dsm alternators puts out more amps than the manuals.

Car Cannibal · 12-07-2007, 03:09 PM

In general, the TCU will go in limp due to either voltage or a code issue. You might not have needed the new TCU when your voltage issue was corrected.

And a lot of Auto's go to the 90 amp alts ( canadian ) or 135's from 4alterstart.

My alt generally has a poor idle voltage when it's on its way out but the cruising volts are ok. If I keep driving on it then both eventually suck and I for sure need a rebuild. Oh well, lifetime warranties are great for cars who's 02 pipes are an inch away from them.

DSMcamaro · 12-08-2007, 12:44 PM

Quote:

Originally Posted by Car Cannibal

In general, the TCU will go in limp due to either voltage or a code issue. You might not have needed the new TCU when your voltage issue was corrected.

I put in a new alternator and battery before changing the TCU. The TCU was bad.