Antilock Light On then Off and Motor Juumps - PeachParts Mercedes-Benz Forum

86-300sdl · #1 09-01-2014, 04:56 AM

86 300SDL .....603 motor

On occasion my Antilock light will stay on at start up. Maybe 30 secs to 2 minutes. When it goes off the motor will surge...actually jumps to where I need to be ready with the brakes....

Does that sound like a common circuit that when clears sends a signal to the IP's electronic idle control to bump the fuel a tad causing the surge?

Do any of the "cubes" in the fuse box involve this / these circuits?

Or any other thoughts would be great!

Thanks!

Jeremy5848 · #2 09-01-2014, 11:16 AM

This is an electrical problem involving the EDS (Electronic Diesel System) and ABS systems. They are not interconnected per se but do share some connections such as power and ground and perhaps the wheel speed sensors. I would go through the parts of the electrical system covering these subsystems looking for bad (corroded) connections or pinched/partially broken wires.

Check carefully all fuses protecting those circuits. Don't just look at the fuses or put a meter on them, actually take them out, check for hairline cracks, clean the ends, check the clips holding the fuses, etc. Change any aluminum fuses to brass.

Find all ground points listed in ETM (Electrical Trouble-shooting Manual) for those circuits. Unscrew them, clean the mating surfaces, reassemble.

Pull the OVP (over-voltage protection) relay and check/clean its fuse(s) and terminals. Swap in a spare if you have one. OVP supplies power to both ABS and EDS; it is the one true common point in those two subsystems.

Check/clean the ABS wheel sensors. Try to figure out why the ABS light is coming on in the first place. It's just possible that there is a low-grade short circuit somewhere in ABS, not enough to blow a fuse but enough to cause a power surge (as you have described) when the ABS system finally manages to clear itself.

Keep us informed.

Jeremy

86-300sdl · #3 09-01-2014, 01:42 PM

Quote:

Originally Posted by Jeremy5848

This is an electrical problem involving the EDS (Electronic Diesel System) and ABS systems. They are not interconnected per se but do share some connections such as power and ground and perhaps the wheel speed sensors. I would go through the parts of the electrical system covering these subsystems looking for bad (corroded) connections or pinched/partially broken wires.

Check carefully all fuses protecting those circuits. Don't just look at the fuses or put a meter on them, actually take them out, check for hairline cracks, clean the ends, check the clips holding the fuses, etc. Change any aluminum fuses to brass.

Find all ground points listed in ETM (Electrical Trouble-shooting Manual) for those circuits. Unscrew them, clean the mating surfaces, reassemble.

Pull the OVP (over-voltage protection) relay and check/clean its fuse(s) and terminals. Swap in a spare if you have one. OVP supplies power to both ABS and EDS; it is the one true common point in those two subsystems.

Check/clean the ABS wheel sensors. Try to figure out why the ABS light is coming on in the first place. It's just possible that there is a low-grade short circuit somewhere in ABS, not enough to blow a fuse but enough to cause a power surge (as you have described) when the ABS system finally manages to clear itself.

Keep us informed.

Jeremy

Thank you so much Jeremy! I'll run through your procedure this morning....but where can I find the ETM (Electrical Trouble-shooting Manual)....is it online some where?

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