I have a 1992 Mercedes s500 which occasionally the rev counter suddenly jumps up & down then stops completely then ASR light comes on and the car goes into ''limp mode'', then after a few minutes it suddenly starts working again but i have to turn the car off & then back on to re-set the problem.is it possible the sensor to read the rpm is the problem

ASR can be dangerous, I highly recommend a dealer or highly recommended mechanic look at. Could be complicated, or just some loose connections affecting both asr and Transmission.

ASR light on, mostly caused by a brake switch,

Check ASR system. Wheel sensors would be a good start because thats what the system checks for speed difference at the wheels. It reduces power to keep you straight on the road.

need more information what's the your car sl 500 or s500 and also need to know what time it's happen when first acceleration light comes on or while drive car some time it's comes on, other thing would like to know every time ignition off and start is the asr light off? if you give more information can be solve your problem,

Tire speed on each tire is checked if not the same the ASR kicks in and powers down the engine to stop you from sliding around. Check the wheel speed sensors to start.

Cable binding, do not press gas when starting, speed sensor on the wheel could have failed or be dirty, ASR module could be bad, upper engine wiring harness could be failing. Go to benzworld dot org or peachparts dot com for more specific help and guides.

The first thing to do is have the battery and the charging system checked,if the asr system detects less than 11.5 volts or loss of power it shuts down and turns light on,

yes they can but unlikely-more likely a bad over voltage relay(powers up idle speed computer) or wire harness-your vehicle is probably a hfm type fuel injection they changed from lh that year. find out if it is lh check the fuses in the base module located in the passenger side of the engine compartment under a cover held in by 4mm allen head bolts-alot of times these control units have intermittent contact with there connectors. asr stands for acceleration slip regulation-both isc and asr communicate via can system to monitor throttle position- ea isc cc-idle speed cruise control and electronic actuater(throttle)-hopefully i have helped

To make sure the problem will be solved, you have to replace left and right ETA's and engine wiring harnes.I had the same problem with my 1994 S600. expensive.Mercedes had wiring problems on all models from 1992- 1996 (insulation on wires would crack,and wires would short circut).

abs light comes on and off during normal driving conditions also surges forward when the ligt turns off