I just replaced the AC expansion valve. In doing so I had to remove the instrument cluster and a lot of components underneath the dash. This included disconnecting some wires on the center console. After reinstalling all I started the car and the instrument panel lit up with very bizarre lighting. Brake light, battery light, ABS light all lit and the instrument panel did not light when headlights on just to mention a few symptoms. Needless to say there was an issue. I double checked that the wires were reinstalled correctly on the console. But I'm embarrassed to say that when I removed the cluster, which I have done before, when removing the 15 pole coupling I opened it up instead. I did find the correct schematic and believe that I reinserted correctly. However, before I open it up and check, I was wondering if anyone can shed light on the problem and tell me if I should be checking something else, or is it a mis-insertion in the 15 pole coupling? Help would be greatly appreciated.

Folks reading your post do not know what vehicle is involved; do you?

Sorry, so frazzled I forgot to include. It's a 1989 300SE. (W126)

Confirm that the cluster ground is good, probably a brown wire in that connector.

__________________
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ED:

At the moment, attempts to upload files of plug data are failing.
If you wish, contact me thru my user name email and I will send the files that way.

Frank, I sent an email via Peach Parts private email but never heard back. Not sure how to properly retrieve your user name email from this site.

Update: I found the wire schematic. Checked pin placement & I was one off. Reset all and all OK. EXCEPT I lost the illumination of the dash. Now looking into that. Both bulbs are good - FYI.

Some of the functions of this website seem to not be working; upload of files is still failing.
Perhaps the site is also not sending emails on through.

I found this online and did what it recommended and I got all lights - all good. But I don't know what it means. In other words, what is causing this ...

Verify Illumination (Optional): If you find voltage at socket #5, you can jump (connect) socket #5 to socket #8 to see if the instrument cluster bulbs illuminate. This helps confirm the rest of the circuit is functional.

Afterwards, shunting the rheostat still resulted in no illumination. So, with that being said, could it be the rheostat or did I foul something else up? Trying to be thorough before I jump and buy another rheostat while that's not the problem.

E:

One more test is required. With the instrument cluster removed, connect an ohmmeter between pins 5 & 8. Turn the dimmer knob and note the change in resistance. If that circuit is open there will not be illumination.

Ohmmeter read .003. Turned the dimmer know and no change occurred. No illumination.

If the circuit resistance is in fact .003 Ohm there should be illumination. That low a resistance is the equivalent of jumpering the socket from 5 to 8.

A cluster that was just checked on the bench showed resistance from ~.6 Ohm to ~ 12 Ohm when turning the knob, albeit very jumpy, with a few gaps.

Just double checked my reading. Ohmmeter set on 2k - this time it read .002. Confused here since I did get full illumination when I jumped sockets 5 & 8. Here's a picture of the rheostat. Don't know if that will aid.

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.002 on a scale of 2000 Ohms = 2 Ohms
At 2 Ohms there should be some illumination.

Got nothin...