[W126 Coupe] Strange gauge lights error, any ideas?

[Gerry Van Zandt]

I had this problem about a year ago in my 1989 560SEC.

It turned out that my wiring harness that attached between the battery, alternator and starter had a corroded/frayed end at the attachment to the alternator. The wiring was about 50% cut at the connection due to age, constant rocking of the engine and constant use. I could wiggle the cable and the dim lights would go off, but eventually the rocking of the engine and flexing of the harness would gradually remove contact and the lights would come on again, very dim.

I ordered the harness from MB (it was around $160 I think) and it took me about 1.5 hours to replace it in my garage.  Lots of connections but a very satisfying fix.

If you know your charging system (alternator output, battery, voltage regulator, etc.) is good, then I'd take a very careful look at this harness, It's a black-sheathed thick cable on the passenger side of the engine that leads from the alternator/starter area all the way up to the battery + terminal.

I've heard of this issue happening to a few other folks, so it is not uncommon. My car had around 175K miles on it FYI.

Good luck!

Cheers,
Gerry




On Feb 25, 2010, at 3:35 PM, mbcoupes-request at mbcoupes.com wrote:


> Message: 1

> Date: Thu, 25 Feb 2010 11:30:32 -0700

> From: "Ernie Stephens" <stevetsg at msn.com>

> Subject: Re: [W126 Coupe] Strange gauge lights error, any ideas?

> To: "Mercedes Coupes Mailing Lists" <mbcoupes at mbcoupes.com>

> Message-ID: <SNT137-ds5B78E80B63828E9CB1DE4D4400 at phx.gbl>

> Content-Type: text/plain; charset="iso-8859-1"

> 

> Josh,

> I have been having similar issues with the warning lights coming on intermittently or glowing dimly. I took my car in for service yesterday and had them top off everything and it seems to have solved the problem.  I don't know if the warning lights share a common ground or if there is a leak (faulty diode) or if it was just a coincidence but you might just want to make sure that all of the reservoirs (even the windshield washer) are topped off.

> Good luck,

> Ernie


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