Side mirror in-out motor connection

[jstone85]

I’m having an issue with the in-out movement of the right side mirror in my 1990 300E 2.6.

The connection to the in-out electric motor in the right side mirror only produces +/–1.2 V (connections 2 and 5 in the pic).

I have cleaned the connections as best as I can with a small brush (hard to get in there properly) and I have checked that the voltage from the mirror control switch is +/–12 V when using the in-out lever.

I have also checked that the in-out electric motor works when using a 12-V battery. The up-down motor works as fine as-is.

So somewhere from the mirror switch to the mirror-plug the in-out signal fails. From looking at the wiring harness it doesn’t appear that there are any connections from the switch the mirror-plug that could be corroded.

It’s not really an option to pull apart the plug to clean the terminals as you can’t put it back together. So what other options do I have for tracking down where the failure is?

Any thoughts are much appreciated.

 

[emerydc8]

I'm sure @gsxr will know but does the right mirror go through the convenience module located under the left rear seat? Assuming you have seat position memory on the door switch, that switch also controls the position of the mirror and telescoping steering wheel. I don't know if the memory also controls the right mirror too. Have you tried to change to the other seat position to see if the right mirror moves? Also, the mirror control switch on the center console takes a beating. If any liquid is spilled that's where it usually ends up.

 

[jstone85]

I replaced the mirror switch with a new. I also opened the switch-connector and cleaned off any corrosion that was there. It produces the correct voltage when using the in-out lever of the switch.

The car doesn’t have seat position memory nor a telescoping steering wheel.

Judging from the diagram, the signal goes directly from the switch to the mirror-plug. So I assume the failure must be along this path.

 

[emerydc8]

There doesn’t appear to be anything between the switch and motor. I would start at the door hinge where the wiring flexes the most.

 

[gsxr]

Assuming you have +12v at the switch, but not at the mirror... use an ohm meter to measure resistance of the wires between the switch and mirror. I agree with Jon, the most likely cause is a wire damaged by flexing at the door hinge area. You may need to remove the wire from the door / A-pillar for closer examination and/or repair.

Wouldn't hurt to check the other end of the harness, upstream of the switch, to make sure the +12v source connections are clean and tight before you start yanking wires out of the door.

 

[jstone85]

Thanks for your replies. I'm only just now getting back to working on this.

Assuming this is a damaged wire at the door hinge (which sounds highly likely) is that something that I can repair or would I need to replace the entire wiring harness?

 

[gsxr]

Most any wire harness problem can be repaired. Replacing the entire harness is likely impractical, and the harness is likely NLA.

 

[jstone85]

I started pulling the mirror wire out to take a look. I’m having a real hard go at removing the kick panel. Seems like the upper hook on the back is stuck and I don’t want to break it. I found some pages about removal, but not too helpful actually.

Would it be easier to remove the rubber guide between the body and door to yank out the wire?

 

[gsxr]

Before taking anything apart further, I'd start by finding each end of the wire harness (possibly the switch, and the mirror connector). Check for continuity of each wire and confirm 100% that you indeed have a broken wire, before tearing into things. Use the factory schematic to determine which wire colors / pin numbers to test between.

 

[jstone85]

I did confirm that earlier today. Measuring resistance from the switch to mirror connector according to the diagram. There was resistance from 4-to-3, and 5-to-2, but no reading 1-to-5 — consistent with my issue (up-down connection OK, in-out connection fail).

 

[jstone85]

Turns out pulling the wire was harder than I expected. First, I couldn’t easily determine which of the wires going to the door is the outside mirror and didn’t want to pull too hard on any of them to find the right one. Any pointers (or links) for pulling out the wires through the door? (And reinstallation)

Thanks!

 

[jstone85]

I got the wire out and confirmed that it’s not damaged—there’s continuity from the switch to just before the plug. So the issue is with the plug itself. I suspect that the connectors must be corroded.

You can’t open this plug since it’s one plastic piece. How would I go about cleaning connectors like these? (The bad connector is #5.)

 

[gsxr]

Great question. I've seen these connectors get badly corroded with fuzzy green stuff, but yours looks clean. I'd use something small like a dental pick to gently scrape each of the contacts. See if that gets it working again. If not, something may have failed inside the connector itself, which would be very unusual... but not impossible.

 

[TerryA]

Is that the connection to the mirror at the door top triangle? My 93 500E connector there is flat plug with I believe 4 connectors in it. I happen to have it disconnected at the moment because I haven’t put the interior triangle back on.

 

[jstone85]

@gsxr I used a small tool to scrape the contacts, but no luck. The bad contact doesn’t even look to have much green—there are others that look worse that have continuity.

So I think the issue must be inside of the plug. Looks like there are a couple outside heated mirror wiring harnesses on eBay. I don’t think I’ll be able to put the plug together if I get it open. I’m thinking to crimp on connections for the 5 wires running to the plug rather than replacing the entire harness.

 

[jstone85]

@TerryA Yes it’s the connector to the right mirror on my 1990 300E 2.6. There are 5 connections in this one.

 

[jstone85]

I received a used harness that I’ll replace for the old one. I haven’t been able to find diagrams of how wires are routed.

Of course I’ll need to remove the center console and get access to the X30 connector block. But as far as I can trace the wire (photo), it looks like I’ll need to remove the front seats as well.

Is there a good resource to find a diagram of wire routes or can tell me what I need to remove to replace the wire?

 

[gsxr]

There's no documentation I'm aware of that shows wire routes - only the schematics.

 

[jstone85]

I finished replacing the wire this weekend. A lot of work getting the carpet out and routing the wires through the door, so it’s nice to have the mirror functional again.