W140 - Crazy Wiper/Warning Lights Fault
 

Can anyone shed light on my wiper problem.

On intermittent wipe all the instrument cluster warning lights illuminate plus the instruments all go to zero (oil, fuel etc) This happens about every six to ten wipes. Its as if the ignition key had been switched off. After about 4 seconds they all go out and the instruments return to normal. The car drives perfectly normally throughout this process and the problem is more annoying than anything.

I have tried changing the main wiper relay sited behind the main fuseboard but the problem persists

All suggestions most welcome
1991/2 140 V12

Low voltage condition
Check bat voltage and alternator outout...

Thanks Arthur. Battery resting voltage 13+ volts, alternator output is good too. Regards from Scotland
Stewart

Try spinning the fuses in their holders...

Not sure about that??

Your battery should measure 12.3 Volts DC after a "load" test (700amps) with the engine off.
When the car is idling (1000rpm) it should be around 14.3 volts under normal load.

If it measures 13 volts, that's too low.

I know that this is a bit late but you should consider your combination relay, this is a computer with a few relays stuck inside. You have to remove the top of the fuse box to get at it and it's a biggie.

It controls the wipers, indicators, hazzard flashers, rear demister AND YOUR INSTRUMENT CLUSTER!

They are prone to failure and aren't a bit cheap. There are three connectors on the underside, you could reseat them. Don't force any connectors off! They are hard to see and get at but two connectors with fewer wires pull off but the big one has a safety sliding mechanism which can only be released after removing the pull off connectors.

My wipers have gone a bit nuts, they sometimes run and change speed all by themself. So far I have replaced the wiper relay and 3 (yes three), combination relays. If I can't get it sorted this weekend, I am going to build my own wiper control system with less logic (but also less fail safe).

M

It could be low voltage from the alternator, a bad capacitor in the instrument cluster (voltge regulator), maybe the relay. Mine started doing it out of the blue, wipers, turn signal, the SRS comes on. Then they all come on and the guages go to zero for a second. It has not done it lately. Do a search on, http://www.benzworld.org/
there were many postings including pictures
http://www.benzworld.org/forums/search.php?searchid=944083

Had the same problem COMBINATION RELAY all is well again