ASR light / limp home mode.

Lurchio

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Hi everybody! Nice to see 'ordinary folk' owning these lovely cars and helping each other out. I have a 1991 500SL, 58k on the clock. During the previous owners time, it was latterly 'stored' for five years, doing about 200 miles per year. I've bought it, and resolved a lot of the probs related to that, but theres one thats just started. Yesterday, the ASR light came on and the car went into limp home mode (as it should when it lights up!). Did the old switch off and on ignition and it cleared. Used it today, same light, effect and cure, and its currently okay. The tyres are all the same wear level and at correct pressure, traction was never lost on any wheel when the light came on.
If it helps, I've also noticed that the battery overflow pipe is discharging fluid after a run, the battery appears new(ish).I've checked the rate of charge on a warm engine, and its 13.5 volts at the battery terminals.

And finally (poss red herring) this has only started since I swopped the radio cassette unit, Grundig for Grundig, and all the connections are correct!

Hope someone can help, I've heard of the OVP relay playing up, but thought this protected the ECU's etc. Thanks.
 

television

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The OVP relay is an important part of the ASR as it supplies an output to the ASR system.

The Grundig radio may have killed the speed signal, that could do it, I think off the top of my head it is on pin 1
 
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Lurchio

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Cheers, in order to try it, I've just isolated the constant 12v, earth and aerial supply to run on the stereo, disconnecting the 12v ignition feed and a spurious lead which turns out to be a backlighting supply for the display, so it says in the book! Keep my fingers crossed, let you know, you're a gent.!!!:D
 

bigdaz1970

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i have a simler problem , not long had my e320 cdi , but its got an after market radio in her , how do you test to make sure its not the radio thanks
 
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