Questions and Answers

Saturn SL2 Transmission Is Overheating Q. Vince, I e-mailed you about four or five weeks ago because my temperature light would go on after 25+ miles of freeway driving. Thank you for the response, it was greatly appreciated! I did take it to an independent mechanic, I am fed up with the dealer! They came up dry. Here is a brief review of the problem:

1991 Saturn SL2 with 4-cylinder engine and automatic transmission. Temperature light went on after 25+ miles steady freeway driving and dealer says it was a faulty temperature sensor so replaced it. Scenario happens again and dealer says the wire for temperature sensor is loose so they fixed it.

Scenario happens again, dealer can't find anything wrong so they take on freeway test drive and light does not come on. Independent mechanic looks at it, I told him about what you said with cooling fan but they checked and said it is working okay, and comes up dry.

I told both the dealer and the independent mechanic that I SMELLED something burning off the engine after every one of these freeway drives. It is not something that was a characteristic smell prior to this scenario starting. The last two freeway drives, afterwards, I have had transmission fluid puddle under the car.

The temperature light means, according to Saturn owner's manual, that the coolant OR transmission fluid is overheating. My brother, who is a mechanic, looked at my car after the last time when I found transmission fluid puddle and he said that there was too much fluid and the system vented it out while I was driving at higher speeds. He checked the transmission dipstick and it was high.

I took it out on a 45-mile drive last night to LA. I was stuck in traffic and not going consistent freeway speeds on the way up there. The light did not appear. However, on the way home at consistent freeway speeds it DID GO ON and stayed on. This morning there is a puddle of transmission fluid under the car.

Temperature gauge, in every scenario, has read normal temperatures. There is no diagnostic code coming up on the computer so NO ONE KNOWS what to do. What in the world is going on??

Thanks,
Jennifer

A. Sounds like nobody knows what that light actually means! If there is a temperature gauge, then most likely is not a light for the coolant temperature. This may be good information for the dealer, although they should know this! Let's say the light is for transmission fluid temperature. Then the sensor they replaced in the engine would not help you. See what I mean? Maybe there is a sensor in the transmission that is controlling this light.

Maybe the transmission is overheating. It makes sense if you are seeing a puddle of transmission fluid after a light coming on. If it's overfilled it should be drained and filled to correct level first. I would do this before anything else. There still may be another problem with the transmission, possibly a blocked cooler in the radiator? Stick to your guns and make sure you explain yourself clearly.

Transmission Temperature Sensor/Switch

PURPOSE:
The transaxle controller, located inside the powertrain control module (PCM) receives five signals from various switches and signals and two signals (vehicle speed and engine rpm), internally from the engine control module, also located within the PCM. The PCM uses this information during control of the transaxle shift points.

OPERATION:
The transaxle fluid temperature sensor is a thermistor-type sensor located in a transaxle pressure port near the pressure filter. Sensor resistance increases as temperature decreases and decreases as the temperature increases. The PCM supplies a five volt signal to the sensor on circuit 585. The PCM monitors the return signal as it varies up and down with Circuit resistance. The voltage value on the signal line is converted to a temperature value internally by the PCM.

LOCATION:
The transaxle fluid temperature sensor is located in a transaxle pressure port near the pressure filter.

Transmission Temperature Sensor/Switch