If both dash lights are not working including the lights in the upper center console the problem is most likely in the dimmer switch located on the back of the instrument cluster. This is also call the potentiometer providing variable resistance in the wiring to the bulbs. When the potentiometer gets corroded or comes apart your dash illumination lights will be totally dark
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Kent has come up with a good method to repair these old dimmer switches. Since they are no longer available new you either have to find a good used one, fix the one you have or bypass it all together. In this part he covers how to bypass the dash light potentiometer switches in the W114, W115 W116 and W123 chassis from 1968 to 1985. The principles will apply to other chassis as well but are not specifically covered in this video. ALSO COVERED are other things that could be causing your dash lights to not work after either repairing or bypassing the switch.
NOTE: This is Part 2 of a two part series. If you would like to know how to repair or restore your dimmer switch be sure to check out Part 1. Kent goes over the design and theory of the switch, how to determine if it is repairable, and the step by step procedure to take it apart, clean it, fix it and put it back together. See related products for a link to Part 1.
This video DOES NOT cover detailed information on the removal of the instrument cluster from the dash. Kent just briefly alludes to some of the key steps you will need to get it out.
Total Run Time: 16:10
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Important note: This video manual may or may not include all the information you will need to troubleshoot and/or repair your specific problem/s. Please read the full description carefully to determine if this video is applicable to your year and model and contains the information you are looking for. If not, please refer back to our "Solutions Finder" and enter your chassis number and the specific problem you are having to see if we offer a solution.
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How to Repair Your Dash Light Dimmer Switch - On Demand Video
If both dash lights are not working including the lights in the upper center console the problem is most likely in the dimmer switch located on the back of the instrument cluster. This is also called the potentiometer providing variable resistance in the wiring to the bulbs.
Instrument Cluster Removal and Component Replacement By Kent Bergsma - Download
For all 108, 109, 114, 115, 107, 116, 123, 126, 201, and 124 chassis from 1965 to 1995. I wrote this repair guide to show you how to properly remove your instrument cluster and replace worn or failing components. (NOTE: This is not a detailed manual on how to repair the components.