I bought a 99 convertible over xmas and have had several electrical problems that are intermittant. Sorry for the long post but I'm looking for a place to start with this...

1) drivers memory seat likes to fully extend upward. After a few seconds, it can be put back in position with the control. It may shoot right back up again repeatedly or it may be good for weeks. Seems to happen more often on bumps or if something else electrical is activated like turn signals, but not always.

2) Outside temperature display will suddenly show incorrect temp by about 20 degrees too low and brings on heater when not needed. After some period of time returns to correct temp.

3) DIC reports ABS sensor problem - disables ABS and traction control. Seems to happen after a bump in the road, but not always. Is always ok after car is stopped and restarted.

4) Gas guage has dropped to zero twice. Fine after car stopped and restarted.

5) Twilight Sentinal waits until it is pitch black out before turning on headlights. I have disabled it for now.

I checked codes on the DIC and this is what I see:

P0461 H - fuel level sensor 1 circuit performance
C1222 H - RF wheel speed sensor input signal is 0
C1226 H - LF excessive wheel speed variation
C1282 H - ?
C1286 H - steering sensor bias malfunction
C1291 H - open brake lamp switch contacts on deccel
C1292 H - ?
B2262 H - horizontal position sensor FIT
B2172 H C - seat front up switch shorted to GND
B2182 H - seat rear up switch shorted to GND
B2187 H - seat rear down switch shorted to GND
B2605 H - seat front vertical position sensor failure
B2606 H - seat rear vertical position sensor failure
plus several U1064 H, U1096 H, U1016 H - loss of communication with ...

 

ttt

 

Do you still have the stock Delco battery? If so, you may want to check the positive terminal for a leak. If you still have the stock Delco and don't find a leak, dump it anyway! Your computer is directly under the battery and it is notorious for leaking on and destroying the pcm, that may be why your getting all the different codes. Mine did it, 2 weeks before the warranty ran out, and it's $$$$$! Optima Red Top is a popular battery on the forum.

David

 

1)make sure seat adjuster goes to full travel in all positions.Broken adjusters are common as is a faulty seat control module under the drivers seat.You could also have a pinched wire under the seat. :yesnod:
2)Replace the outside ambiant air temp sensor located rearward of the right side of the front air dam.You will see the sensor probe protruding out of the radiator baffle under the car.This sensor gets water in the connector terminals and often a new connector terminal also has to be spliced in because of corrosion.The sensor is about $8.00 :yesnod:
3)Replace the left and right wheel speed sensor jumper harnesses (harness coming off the wheel hubs) These harnesses are mounted to the lower control arms and get open curcuits from suspension travel over a period of time:yesnod: About $25.00 each...You may also need a steering position sensor in the steering column for the 1286 code...
4)The left and right fuel senders have been updated for the fuel gauge issue BUT it is not a guaranteed fix and rather expensive.
5)Replace the ambiant light sensor.This sensor is located in the center grille on top of your dash (it pops out) :yesnod:

These are all very common issue's with the C5 :thumbs:

 

Thank you! I was hoping these would be well known problems. I'll check the battery as well.

 

Do the OPTIMA as it could very well be the problem. If you have a leak, THOROGHLY clean ALL the corrosion so as to eliminate any future problems. Good Luck ! :cheers: