1992 500e check engine light on after starting cold no codes
 

Please help me to deturmine fault?

My 1992 M119 had the check engine light came on after starting cold. The code reader light comes on when pushed and there are no codes stored. I checked codes again and got no codes and the check engine light was still on. I checked for codes again (none) and then held the button down for 45 seconds and then shut the key off for 45 sec and then on for 10+ and still have a check engine light and no codes.

Please let me know what i should do next, i am guessing that i need to replace harness but am holding off since my G/F may want something other that an wiring harness under the tre for the holidays.

Jeff AKA Moose

You would need to read the codes from each module. You can build your own or purchase one from Jim.

http://pages.prodigy.net/jforgione/MB_S500.html

I would let it cycle the CE light on for a few more times to see what if any codes are thrown.

To turn off the light, turn the ignition on (the stop just before you crank the engine -- you should hear the injection system engage but don't turn on the car). Hold the button down for 3 seconds, release, and count the blinks. Turn the key off, wait a second or two, then turn back to position 2 (don't crank engine). Hold the button for 8 seconds, then release. Turn key off, then turn engine on. Light should be gone.

Wait for CE light to trip again, and repeat process to pull codes and reset light.

A CE light is going to be triggered by something related to the emissions system. There are a few common culprits -- brake light switch, idle switch, o2 sensor, transmission upshift delay, etc.

Don't jump to the conclusion that it is a harness -- typically with a harness issue, you will see and experience running anomalies, stumbling, etc. of a fairly intermittent nature. Also you will see the car often go into "limp home" type mode with a harness, whereas this isn't necessarily the case with a CE light.

Cheers,
Gerry

Jeff, the Check Engine light was an early warning in our 1995 E320 that the overload protection relay was about to fail. Initially the CE light was on, but the engine ran fine. Then the CE light was on, engine sputtered a bit and the overload protection relay buzzed. Finally, the engine would not start. Installed a new overload protection relay and all is well.