Back Lights/Dimmer Switch Not Working, Missing Part of Wiring Loom??

[thescassidy]

Hello, so attached are two images of the connector in question. I've noticed an issue where the backlight/instrument cluster/switch lights don't illuminate when I turn the lights on. I've managed to bypass and give direct power to the positive or possibly ground wire (?) and they all turn on so I know it isn't an issue with the lightbulbs being out. Furthermore, the dimmer switch doesn't seem to have any effect when I'm bypassing - they stay at one brightness. These wires pictured seem to have some relevance because when I connect the two prongs, via a small wire, the entire instrument cluster illuminates - though again the dimmer has no effect.

Long story short, it seems the previous owner has removed this piece of the harness and I'm not sure where it should connect to even if I had it. If anyone could send a picture of this connector in their own car for reference, I'd greatly appreciate it. I'm also interested in purchasing this part of the harness if that's even a possibility or there's someone who happens to be parting out an e21 (mine's an '83).

**Edit**
- I should also mention that the white wire coming from the back of my radio, marked as "battery" on the back where it enters into the radio, is not plugged into anything. When putting 12v to it, the radio backlight illuminates. Does anyone know whether this wire is of consequence when it comes to this circuit?

Any tips are greatly welcomed.

Best,
Sean

IMG_7622.jpgIMG_7621.jpg

[cgifool]

Although the gray/blue wire does seem to go to the dimmer switch (according to the diagram), I looked on my car and mine is also not connected to anything. It's just clipped up to the right of the intermittent wiper relay on the firewall like its for some accesory (visible in the background of your photo).

IMG_3518.jpg

[thescassidy]

Well shoot, that's good news kinda! Maybe I can solve the issue with what I have. I too saw that on the diagram but couldn't figure out where that wire would have gone too. I'm also getting 12v from the green/white wires despite the diagram (I think) indicating that the power should be going through the "gry/bl" wires. Again, I think.

Thanks for the response, bud! Still interested to see what others might have to say...

[GDAus]

Well shoot, that's good news kinda! Maybe I can solve the issue with what I have. I too saw that on the diagram but couldn't figure out where that wire would have gone too. I'm also getting 12v from the green/white wires despite the diagram (I think) indicating that the power should be going through the "gry/bl" wires. Again, I think.

Thanks for the response, bud! Still interested to see what others might have to say...

Well .. that's connector "C45 (2-pin, in-line) On Body Electrical Bracket" (That's from the ETM) ... and it's for an automatic to provide power to the range selector light (GREY/blue) and the reversing light switch (GREEN/white) which for an auto is part of the range selector in the centre console.

So in that connector the GREEN/white is connected to the Start/Run Bus. So with the ignition switch in the run position, if you bridge it to the GREY/blue it will give a return path back to Batttery positive so your dash lights come on.

What should be happening is that there is a wire wound rheostat in the back of the light switch that should be providing the return to the battery but it sounds like there is a bad connection or a break inside the light switch.

A quick fix would be to bridge the GREY/white wire on the light switch to the GREY/blue. That will give you lights but no dimming function. I'm in a similar position .. my instrument lights work ... but only in the fully clockwise position .. if I try and use the dimmer I get nothing! I've thought about pulling the switch apart but it is an alloy casing that has crimp points holding it together ... so I'm not sure if I could get it back together again without a lot of hassle. I can live with the lights on full brightness.

Cheers

[thescassidy]

Well .. that's connector "C45 (2-pin, in-line) On Body Electrical Bracket" (That's from the ETM) ... and it's for an automatic to provide power to the range selector light (GREY/blue) and the reversing light switch (GREEN/white) which for an auto is part of the range selector in the centre console.

So in that connector the GREEN/white is connected to the Start/Run Bus. So with the ignition switch in the run position, if you bridge it to the GREY/blue it will give a return path back to Batttery positive so your dash lights come on.

What should be happening is that there is a wire wound rheostat in the back of the light switch that should be providing the return to the battery but it sounds like there is a bad connection or a break inside the light switch.

A quick fix would be to bridge the GREY/white wire on the light switch to the GREY/blue. That will give you lights but no dimming function. I'm in a similar position .. my instrument lights work ... but only in the fully clockwise position .. if I try and use the dimmer I get nothing! I've thought about pulling the switch apart but it is an alloy casing that has crimp points holding it together ... so I'm not sure if I could get it back together again without a lot of hassle. I can live with the lights on full brightness.

Cheers

Thank you sir! I have a manual, so it makes sense that nothing is connected to those wires.. Upon messing around with it last night, it seems that if I pull my light switch out gently the first time, the backlights turn on and the dimmer works as well! I must have overlooked this before. Problem kind of averted!

Thanks for the tip