jayjw

I have a 94 LS400 at 88K miles. About one week ago, every morning when I first start the car, all the indicator lights in the instrument cluster are normal first. But after driving less than a minute, the TRAC light came on, then the check engin light came on immediately. After a few seconds, the check engin light was off, but the TRAC light remained on. If I kept drivning, the TRAC light would remains on. If I stoped the car and start again. Everything went fine, the TRAC and check engine lights wouldn't come on. It seems something to do with the temperature.

I searched the forum and some post reminded me that the battery condition could cause the problem. So today I checked the battery and I found out the battery was OK, but the connector to the battery was really rusty. So I disconnected the connector and cleaned it up. After I put the connector back on and started the car and drove to work. The TRAC light problem totally gone.

I thoungt there could be two possibilities.

1. The rusty battery connector caused low voltage to the car which caused the traction control unit problem.

2. Disconnected the battery for some time while I was cleaning the connector. This would reset the ECU and the TRAC problem went away.

I think no matter what was the real reason for solving the problem. Checking and cleaning the battery connector is a good practice, especially before the winter.

jayjw

Oops, I posted too early. I was not the battery connector problem.

After driving about 100 miles, the TRAC and Engin lights came on again. I run the diagnostics and got error code 41 which saying TP Sensor Signal problem. I searched the net about the throttle position sensor problems, and I found out some articles saying the TP sensor need to be cleaned and adjusted from time to time.

Last weekend I removed the TP sensor from the car. It was very clean, nothing need to be cleaned about. I then adjusted the sensor postion a little bit. There are two screws to secure the sensor to the throttle body. I turned the sensor counter-clock wise a bit to make the throttle position a little bit higher than it was before. After that, I started the car and drove around, everything seemed fine. The idle RPM is between 650 and 700.

I haven't had the TRAC and ENGINE lingts on for a week. I think I really nailed the problem this time.

RUDENESS

can u post a pic of the TP sensor, i have the same problem my chk eng. light and my trac off light comes on at the same time and stays on...

jayjw

The TP Sensor is very easy to locate. Follow the air intake (the big plastic tube), it is at the end of the air intake, attached to the throttle body. It is a 2 inches round circle thing with 4 wires connected to it. You can let someone to press the gas pedal, you will see some part is moving at the throttle body.