ABS pump
 

'94 E320 Cab....ABS pump actuates immediately after startup. is this a test function?

Does it pump continually?

I had this problem after I accidentally shorted a live +12v wire on to the case of the ABS ECU :eek:

The light wasn't even coming on, but it was pumping the whole time. It's not at all good for it, and you should disable it if this is the case.. either unplug the ABS ECU (a search on this forum should tell you where it is) or perhaps the fuse for it.

Any resolve?
 

My car (95 E420) is doing the same thing and I'm wondering if it's normal or not. I spoke with a couple of mechanics at my local dealership and they said that this is part of its normal 'test' cycle following the start of the car. Does this so called 'test' actually run the pump?

Yes it does. Normally it is hard to hear, but if you roll forward with your foot on the brake, you'll feel it run for less than a second about a car-length or two from your starting position (after first starting the car).

My pump will run with my foot on or off the brake. I called around and spoke with a few shop foremen to get their take on the issue. From what I understand, the later model (94-95) E-Class perform a self test that actually activates the pump where as the older 124s' self test does not. Either way, I replaced the rubber mounts from the pump to the car which helped to damper the vibration from the pump running which helped a little bit.

All 124s I've owned, from '87 through '95, diesel and gasoline, RWD and 4matic, sedan and wagon (should I go on?) cycle the pump one time when you first start moving, with or without your foot on the gas.