Apparent problem with ABS System

[W116-280SEL]

Hi guys.

Model: 1983 380SE

ABS light comes on when the key is moved to the first position, and extinguishes when engine starts.

Drive off, driving along and break -- no light.

Eventually light will come on but I haven't yet been able to determine what the circumstances are.

Once the light comes on it will stay on until the engine is shut down.

I haven't driven an ABS fitted vehicle much in the past so I really don't know if there's a "feel" involved when it is engaged or disengaged.

- Bill

[WGB]

Slam on the brakes and you should feel the ABS pulsate when the tyres break grip.

If the light is on it is unlikely the ABS will be working - but it obviously starts off OK as the original light up is only the circuit test.

1) Check that all the tyres are exactly the same rolling diameter - any inequality will cause what is happening to you as your initial startup is normal.

2) remove and clean every ABS electrical connection you can get at with electronic contact cleaner - easily obtained fronm Dick Smiths, Tandy's etc.

Bill

[Big_Richard]

it can also be a dirty sensor or the encoder wheel/hub which ever it uses.

I would also suspect cooked, and cracked wiring to the front sensors.

[TJ 450]

I second the sensors... they eventually fail and are the first thing you should check when the light comes on.

Tim

[W116-280SEL]

Thanks to everyone for the tips.

KenM has kindly offered to send me a 380 manual on CD, so hopefully it will contain info on how to do those tests you recommend.

- Bill

[jbrasile]

Bill,

Beside the sensors, a low charged battery or defective alternator will also trigger the ABS light even when the car is running, so check to make sure your battery and alternator are working as intended. You should see 13.8 volts if you measure the battery charge with the engine running at idle. Had the same problem with my 500SLC, once the battery was replaced the problem went away.

Joe