How do I check front door electrical switches?
 

On my '91 300CE, I have tested the convenience control module (under the back seat, behind the driver), and it appears I have a a faulty lock switch. Both of the front doors failed the ohms test (trunk passed)...not sure what this means - or how likely it is that both front door switches are bad.

Anyway, I have pulled the driver's side lock and I see one white wire connected to the lock cylinder - what does this wire activate? Alarm system? Convenience features? How do I test this 'lock switch'?

My alarm works fine, convenience features do not and I've had trouble getting my central door locking to work as well.

ryan

Gremlins
 

1.Do you have an aftermarket (Non Mercedes) alarm?
2.Replace Fuses "A" and "C"
(Notice I said Replace,Not Check...You don't need any more grief.)
3.Ain't No WHITE wire showing in the ETM portion of the FSM for the '90 or '91
300CE.[What's commonly called the "Wiring Diagram"].
There is However a RED wire with a white stripe.
There is also a YELLOW Vacuum Hard Plastic line.
There is a BROWN wire.
There is a BLUE wire.(This is the one that would go to the "Comfort Control")

4.Testing Accomplished with a Multimeter and Wiring Diagram[Spelled FSM]
And an understanding of German Electrons
(They're more "Fussy" [Correct]than American Electrons)
[I know, I know you have an American Battery...How can the Electrons be German?
Apparently Electron's nationality is determined by the Wiring.]

1) No
2)Already did
3) I know - I have reviewed the wiring diagrams for what seems like hours and I can not find the wire that I am talking about either. If you read thru FSM 82-0995 Troubleshooting table convenience control power windows/tilting/sliding roof (ECE), Test step #16, you will see reference to lock switch (S86/1 - driver's side, and S87/1 - passenger side). I can't find these anywhere on any of the diagrams. So, I pulled the lock cylinder and there is a white wire/switch connected to the lock cylinder. This is not the electrical connection at the lock actuator...

However...I may have fixed my convenience/comfort system by replacing the voltage regulator. On what I thought was a separate problem, I was noticing that the battery wasn't fully charging - changing out the VR got me over 14v at idle - and I think it may have fixed this problem.

ryan

Wierd !
 

(BUT ,Not really!) How "OFF" Voltages [and you'd be surprised , Amperage s]
can throw ANY component into fits that you think cannot be explained?

I still want to know what that damn WHITE wire is/goes to...If you find out
please P.M. me.