petern12

Hi, while jumpstarting my '95 S420 at night, I inadvertently "crossed" the jump cable terminals, i.e. clamping the + clamp to the - terminal on the battery and vice versa. Anyway, right after starting up, I found the ASR & ABS lights stay on permanently, and my speedometer no longer works! both the odometer and tripmeter still display fine, but no longer advance, no doubt due to the inoperable speedometer. Everything else electrical is in working order. I would greatly appreciate any pointers. I've check all the fuses/relays and they're all fine. Alternator fully funcitonal. Thanks for your help.

vilamoura

I made the same mistake .... I crossed the + with the - and ASR & ABS lights stay on permanently, and my speedometer no longer works.
How did you solve the problem?

MB AMG

How did you manage to cross the cables?

vilamoura

It was dark and I made the big mistake to connect the + of the booster to - of the car. Stupidity!
The car runs fine. I think that there is something to do with a relais or a hidden fuse somewhere out of my sight.
In my oppinion when power arrives to the speedometer then everything is fixed.
Another user made the same mistake, I wonder how he solved the problem. I wrote him an e-mail asking for help.

vilamoura

Another user advised me to disconnect the battery for about 15 min. and start the car again. Did not work.

MBS420

I had the same situation before. I believe there are 3 or 4 fuses need to be change. after that, everything is ok. But, I don't know where is the fuse box. I heard the mechanic told me there are two of them: One is under the hood and the other is in the truck. What I can remember is they change some fuse under the hood. Hope this will help.

vilamoura

Thanks very much for your reply.
I have just replaced all fuses (front and back) with new ones.
Problem still goes on.
No working speedometer gauge, no working fuel comsumption gauge and both ASR & ABS yellow lights on.
All the rest is working 100%

MBS420

I just called my mechanic, he told me when the fuse is changed, everything should be fine. The sppedometer and others should be protected by fuse from electric shock. If the problem still there, most likely is:
1. fuse is not firmly inserted.
2. drive around to see if computer will pick up the new message.
3. did you check out if the fuse you take out is blowed out or OK? If it was blowed out, then a fuse change should work. If not, maybe the system is burned.

good luck

vilamoura

Thanks once more for your reply.
No fuses were damaged. They all look ok.
I think that unfortunately electronic system is damaged.
Many thanks for your help.

Jer

I am afraid I must concur with vilamoura. Reversing the polarity can do serious damage to the discrete components in these electronic control units.

Benz_Guy_NY

Open up the black plastic computer housing (4 hex screws) where it says "battery in trunk" and check the 4 or 5 10 amp fuses in the car's computer. When my speedo stopped working it was a 10 amp fuse in the computer. Unfortunately I paid a mech. $60 to put the car on the scanner to find out I needed a $ 0.25 fuse.

"this is the rumored SECRET FUSE BOX everyone keeps talking about"

ychachad

The cover on the battery clearly states "Disconnect negative terminal before charging, or jumpstarting, to avoid damage to car's electronic components". Simply put, disconnect the battery when charging, and also disconnect the battery when jumping. I confirmed this with my MB tech, who has experience on MBs for past 35 years. Crossing terminals can prove fatal.

stephane

There was no intervention on my battery, but sometimes ASR & ABS lights are on. It is coupled to an hard sterring wheel (parametric assistance is out of ordrer) and an unoperating tempomat.

Turning the power off and then on makes everything getting rigth.

MB mech. said a captor seems to be wrong.

I know this is a different problem, but could this one(sorry, I don't know the equivalent for the french word "sonde" (borer?)) be a captor problem ?

RapidG

My '95 S320 has the same problem - ASR and ABS lights on, and hard steering - turn it off and on again, and the problem disappears. BUT, after a week, the problem will not be cured by turning the ignition on and off - it's a permanent situation. I have an appointment with a mechanic next week (parking the car in the meantime). I'll post the results. He suspects a bad ABS sensor. Says the steering boost is speed sensitive, and if that sensor is bad, could cause the entire problem.

gam0524

Replaced the fuse inside the base module. Speedometer came back on ans the ABS light turned off. Base module is located inside a rectangular box on the right rear side of the engine room. Open the cover of the rectangular box and you wil see 3 fuses at the very rear of the box. They have red colored fuse.

RapidG

Mechanic says that the ABS speed sensor in the RF wheel is bad. $350 for the part.

92mercedes

I have this same problem with my 1992 Mercedes Bez 500sel as of today ... wasn't having these problems until I gave my car a jump single handled ... Checked fuses THERE OK... I don't know what needs to be done COULD SOMEONE OFFER HELP I WOULD APPRECIATE

Abrar555

did this work ?? I mean after opening the rectangular box and changing the worn out fuse, will the speedometer work and will the ABS light go off ??

Abrar555

did opening the rectangular box and changing the worn out fuse worked starting the stopped speedometer and did the ABS light went off ? please help me and let me know about it..

Abrar555

oh thank you very much..I opened up the secret fuse box and found the fuse was burnt and changed it my speedometer started working...

oldsinner111

yes on the newer models,the computer box is shaped like a casket.Sometimes the electrical plug on the transmission,will pull ATF in computer box.Clean everything good,and let dry,replace transmission plug.

dtaks

I have a 1994 S320 with a similar problem. The speedometer and odometer aren't working. The ABS light is one but everything else works. I checked the fuse in the coffin box (there are 2) and one is blown. When I put in a new one, it blows immediately. I also tried changing it with the battery disconnected. Any suggestions?

oldsinner111

Try replacing both fuses.Sometimes a fuse is bad when it looks good.Check all connections,and wires for fraying.Check on the Mercedes Benz Forum,for instructions

Seeking2know

y_NY;686550]Open up the black plastic computer housing (4 hex screws) where it says "battery in trunk" and check the 4 or 5 10 amp fuses in the car's computer. When my speedo stopped working it was a 10 amp fuse in the computer. Unfortunately I paid a mech. $60 to put the car on the scanner to find out I needed a $ 0.25 fuse.

"this is the rumored SECRET FUSE BOX everyone keeps talking about"[/QUOTE]

Thanks very much!! I followed your advice and my problems were solved! My speedo is now working and the ABS light doesn't remain on after starting. Now I can take my trip worry free! Thanks again!

shrrybaby

i own a 1993 sl500 recently had body work done and the body shop ran the battery dead. Now, after charging the car, my asr and abs light are on and the convertible top won't go down. Can anyone help?