"92 400 se, why are my ASR and ABS light coming on?

[mmaeser]

Thanks for you help on my AC blower regulator! But now my ASR and ABS light are coming on and staying on while driving. I've read the owners manual, says posssible low voltage, pads have been replaced, all tires are same size, not done any towing, just plain old daily driving, car has 90,000 miles. Any ideas? thx,mike

[Ali Al-Chalabi]

Low voltage could cause what you have described.

If you have a digital multimeter, check the voltage at the battery terminals with the engine running to see if it is low.

[G-Benz]

If your charging system is operating properly, you should see between 13 - 13.5 volts at the battery, but no more than 14.4V.

Also run the engine at 1000 rpm with assessories on (A/C blower, headlights, radio, wipers, etc.). Your voltage should still hover in the 13's.

12.5V is borderline. Below 12.5V, and you have a charging problem...

[David C Klasse]

Definitly sounds like a charging problem of those 2 are lit at the same time. Both are dependant upon voltage, and any low voltage would trigger these.
Battery or Alternator!

Good luck!

[mmaeser]

thanks for the tip guys, i'll go check the voltage right now, thx, mike

[turnne1]

Do you have the analog or digital instrument cluster(accumulated mileage,trip.etc)....if you have the analog...there may be some bad news in store for you as many of these cars(including mine) developed shorts in the instrument cluster.....your local dealer should be able to diagnose this problem in 5 mins as it is/was a common problem


good luck

Warren
1992 300SD 125K
Columbus Ohio

If your car has an over voltage protection relay(the little relay with the red fuse in the top) or a fuse in the bank of computers(right firewall) that is blown it will also cause the lights to come on.

[sixto]

I had the same symptoms a couple of weeks ago and it turned out to be worn voltage regulator brushes. Do all the warning lights come on just before you engage the starter?

Sixto
91 300SE
81 300SD

Mmaeser;
Check the voltage but i suspect if that was the problem it would also show up in other systems.
Remove the cover for the control units and replace ALL the 10 amp fuses.
If the light is still on go see a good m.b. shop and have the codes checked.
M.F.

[mmaeser]

I have read all of the above replies and went in to have my codes read...it seems that (3) of my wheel sensor codes are faulty. the autorized benz mechanic said that my 20" wheels and tires should be replaced with factory stock wheels inorder for him to test the wheel speed sensors. he said he occaisionally will replace one sensor but not 3 at a time. Voltage & charging is OK. I do not have a Voltage protector on my model benz. I will replace all my fuses. I have had problems with instrument cluster shorts and had it fixed at dealer with some black box they replaced. the ASR ABS lights start to come on as soon as i drive about 20 feet out of my driveway. by the way i had the 20" wheels on the car for 6 months before i began to have the ABS/ASR light problem. thx again gentle men, i greatly appreciate your help!! mike, 480 563 4344 phoenix.

[sixto]

How does the car know and why would the car care how big the wheels are? The only thing that might matter is that the wheels don't cover/protect the sensors from the elements. Even that's a stretch.

Sixto
91 300SE
81 300SD

[Arthur Dalton]

All tires the same size?
The car is looking for same diam. on all four.
That means same wear and pressure too....

[mmaeser]

tires are same size, air pressure all at 44psi, wheels are same, lights come on after reversing out of driveway and making a sharp radius turn. then lights ABS & ASR lights are on until car is turned off. 10 amp fuses are good. charging is good. codes say three of my speed sensors are bad, seems unlikely! thx, mike