Why Does TCS Activate So Easily?

[AT] Symptom : TCS activates when driving over a rough patch of road.

Solution: Acura service center found that in the '91 in question there was a computer program bug in the TCS unit. Acura sent an updated unit and that fixed the problem.

Cost : Covered under warranty. A new TCS unit would cost $2,000, so give the dealer a try on this one and they may find you have a similar problem.

[A/H] The Traction Control System looks at many things to determine if the rear wheels are spinning too fast. One is the speed of the front wheels (Antilock brake sensors) compared to the rears, and one front to the other front. It also check the throttle position, engine speed, and steering angle sensor in the steering column. If the rear wheel speed changes in relation to the front wheels or the two fronts go a different speed, then the computer assumes that you are in a corner. If the steering angle sensor says that you were going straight and there was no change in the throttle position or the engine speed then the traction control computer gets confused and shuts its self off. Ask anyone who has spun off a track how many different lights were on when they came to a stop.

Clearing the computer by cycling the key will make the light go out but the codes are still in the memory. They can be pulled up by your friendly neighborhood Acura dealer, or anyone with a service manual. For liability reasons I can't tell you how to do it.

 

TCS Error Codes

[LE] The most common problem with the TCS system is a bad ring sensor at one of the the wheels.

[SAN - 2000/9/3] I have a 91 NSX with 80k mi. It had an intermittent traction control failure. The TCS light would come on at irregular intervals. Took it to the dealer and they could not diagnose problem. They replace TCS module and ECU module. This did not cure the problem. I bought the service manual and diagnosed it myself and found about the same thing the dealer did. It gave an error code 3-4 TCS to ECU communication problem. I checked wiring and connectors for open short and continuity. They checked out OK. I also monitored the TCIN (sp?) and TCOUT (sp?) control signals and they were operating as specified in the manual.

Finally my car totally died. It would not start. In addition to the traction control error code 3-4 I had engine code 36. I thought it was low battery. It did not jump start. I charged battery..... no help. The manual indicates the battery voltage can sag to 9.6v and the computers and everything should work.

I heard the main relay unit clicking when I bumped the wires. I took the module out and looked at the solder connections under a microscope. There were hairline fractures but no cold solder joints. I resoldered all connections. Slapped it in and the car runs great. No traction control failure now.

I assume the relay was intermittently turning on and off which would deactivate the ECU temporarily which would then stop communication with the TCS module, intermittently, causing a TCS error code 3-4 to come up.

Most failure modes are mechanical and not the electronics. Look at connections relay etc.

 

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