Mercedes-Benz Ponton Reverse Light Switch

Douglas Broome / / October 23, 2017

International Ponton Owners Group (IPOG) topic

From: Yang Liu [ponton] <>
To: Yahoogroups <>
Sent: Sun, Oct 22, 2017 12:25 pm
Subject: [ponton] reverse lights doesn't work


Today, I realised that my reverse lights on both sides don't work. I checked the bulbs, and they looked good. Can someone tell me how to debug whether it is an electrical issue or something else? I couldn't find much information.



---In, <> wrote :

Where is the reverse light switch on your car? On top of the transmission or on the steering mechanism in the engine bay?

Put the shift lever into reverse. Then, using a test light or a voltmeter, check for power/voltage at the reverse light bulbs and along the wiring in the trunk (boot). If this does not provide the answer, check for power/voltage at the switch itself. Access to the switch if it is in the engine bay is easy. Otherwise access to the switch, if it is on top of the transmission, is possible via a large rubber plug on the transmission tunnel from the passenger footwell. This latter possibility involves some personal contortion but is doable.

A fuse in the fuse panel on the firewall (bulkhead) governs the reverse light. Is the fuse good, or has it blown? You can use a test light or visually inspect the fuse to see if its little wire is intact or not. What other electrical system does this fuse govern? Are they still operating or not? The answer to this question should help you determine where the fault is located? Possibly the ring connectors for the wires have corroded and require burnishing. Possibly the fuse holders have tarnished so as to not allow power to pass. Burnish the ends of the fuse as well as the metal holder. Do this carefully.

Bottom line: Don't be too quick to conclude that there has been a failure within the reverse light switch itself. Too many other possibilities require exploration first.

Ask if you need further help. Let us know the result of your investigation.


Created: October 23, 2017 / Jeff Miller
Last Update: October 25, 2017

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