Weird problem On 97 SL-1 Automatic, Please Help.

gsbadbmr · 02-19-2008, 04:46 AM

Hey everyone. I have a 1997 SL-1 and a couple of days ago the "Service Engine Soon" light came on. Now, the car sometimes at a traffic light or while parked just about stalls, then the RPM bounces up high again. Also, i noticed that while driving on the highway, the coolant temperature stays at the bottom, and my overdrive (D4) doesn't work anymore UNLESS the coolant temperature bounces back up again then the car will shift into D4...when the coolant temperature drops down to the bottom the car downshifts into D3 from D4...it's weird.

Now, last week i had a transmission fluid leak and my garage had pressure washed my whole engine bay and engine to see where the leak was from and they found it. I'm wondering, since this had been done my car has been acting weird. Is it possibble that when it was pressure washed something shorted out? Also, today i brought my car to the garage and have it hooked up to the computer to find out what code triggered the "Service Engine Soon" light but the computer was unable to get any reading from the plug. The mechanic said tomorrow he will try and get power to the plug, and if not he may have to take the dash out of the car because there is some kind of computer under the dash.

Any help would be appreciated. Thanks!

Telyx · 02-19-2008, 10:38 AM

A common problem with S-series before 2001 is the engine coolant temperature sensor (ECTS) going bad. They switched to a brass-tipped sensor in 2001, I believe, but before that, the tip was plastic; after a while, it develops a crack and coolant messes up the sensor and, often, the wire connector. That will cause problems like you're having. Replace the sensor and the wire harness to it (not a difficult thing to do), and it should cure the problem. Make sure the ECTS you buy has a brass, not plastic, tip; most aftermarket sensors will be brass, but the dealer part will be plastic for a 1997.) (The engine thinks it's still cold, so it's probably running rich, which could cause the near-stall problem. Also, the torque converter won't lock up, and I think the tranny won't shift to 4th, until the engine is warm enough for the fuel system to go into closed-loop operation.)

RC1488 · 02-19-2008, 04:18 PM

+1 for changing the ECTS. However, it is not plastic but resin. Coolant will eat through it sending false data to the PCM. The best tip that your ECTS is bad is that your temperature reading is not showing on the cluster. The ECTS is VITAL to MANY systems in the car including but not limited to : fuel management, idle rpms, fan control, shift points, TC lock up times, etc. There is almost never a code pointing to the ECTS, however 9/10 its the ECTS that is the problem.

Aftermarkets are alright but have been known to go bad. I would get the one from the dealer at $17.50. Its worth the money. At the dealer they only have Brass tipped and no longer sell the resin tipped one. They always have that sensor along with the connector in stock in bulk. Replace the connector if there is corrosion on it.

The S-series PCM rarely goes bad. Its always something with a sensor or of the like. There is no reason for anyone to take out the PCM unless modification to the car (tranny/engine swap) is being done. More than likely your OBDII port is having the issues (loose wire etc) NOT the PCM. My guess is you SES code is going to refer to the transaxle, however a new ECTS along with resenting the PCM should clear that code right up.

gsbadbmr · 02-19-2008, 10:50 PM

Thanks for the responses!

Well, it turned out to be my coolant temp sensor so i changed that. I also had another code for a transmission sensor which was also bad, and apparently it is the SAME sensor part as the coolant temp sensor. I also changed the big fanbelt as it was cracked and worn.

After having done the above work, the mechanic reset the "service engine soon" light however it came back on a short period after it was reset with the scanner. Is there another way to reset or get rid of the "service engine soon" light? Maybe disconnecting the negative battery terminal then re-connecting it? Thanks guys!

-g

**Ssicarman** · 02-20-2008, 12:08 AM

If the codes were erased and the SES light has come back on then there is still a problem. The best thing for you do do if you want help here is to get the codes read and let us know what they are.

RC1488 · 02-20-2008, 02:44 AM

^^^^^^^ +1