W126 light bulb for "check engine light" ??
 

Hello members. The archives had no food for thought on my query so here it goes.

My 1989 300SE (W126) went in for a smog cetificate (California) and passed the all emission tests and visual tests but failed the functional test because the 'Check engine light' would not illuminate.

"Please check bulb" :bulb: was the suggested remedy.(come back for retest)

Question is, does this bulb exist or is the 'check engine light' illuminated by another typre of light source?
If it has a light bulb, how do I get to it without massive disassembly?

Any other possible causes for the non-illuminating dummy gauge?

Thanks

Denis

bulb
 

check the fuses in the overvoltage relay, on some models a fuse can be burned causing the light not to illuminate, the fastest way to check this is by briefly pushing the button on the 16 pin connector near the battery, if the little red led comes on, then the fuse at the relay may not be your problem, in order to check the actual bulb the instrument cluster will need to be removed, that is pretty easy if you have the cluster removal hooks

Thanks Carson356, I will have at it tomorrow and will post reults soon. :bulb:

W126 Light Bulb
 

There is a light bulb behind the check engine light. The cluster pulls out using a special tool or you can make one by taking a piece of thin metal 3/8" wide and about 12" long and bending over one end to make a hook (very flat hook). Insert this gently on one side of the cluster and pull out this side. repeat on other side. You may want to get some bulbs before you do this (thet have a special base).

All done.
 

Thanks all, I determined that the bulb was bad and pulled out the cluster only to find that the harness had NO bulb at all!
No clue who took that out. For so many years, never has become an issue with the smog test.
Anyway at first the new bulb did not light up. Cleaned the socket and the bulb worked.
Passed the re-test without incident.

Thanks again.
Den