I have diagnosing the ABS brakes.
The ABS light turns on after a 2-3 min drive.
If i recycle power then it is almost instantly on again.
When the light is off within the first minutes the ABS functions ,OK.
I have checked the OVP and i have the correct duty cycle on pin 3. diagnose socket.
When i checked the two front sensors with my scope then the one on the right did not give any signal.
Got a new one and installed it and when i first checked it seemed okay ,but after diagnosing the battery and alternator output i figured i should measure the sensor which i just installed.
It was totaly open ,compared to my old one and the left side sensor which are 1KOhm.
Reinstalled my old sensor which i managed to get going with some angle correction (it didn´t go deep enough to detect anything).
I have checked the solenoid relay and the pump relay.
I also tried the pump by manually hotwire it for a few seconds.
Did not sound that nice but started.

Where can i found the connector for the rear sensor ?
The amplitude from the left sensor is a bit lower then from the right sensor is that a problem ? (0,2v difference)
Is it common with a new sensor that is defective ?
I have disabled my 4matic since it is almost impossible to run with defective ABS.
The control boxes i have are from the battery and backwards
1. KE-Jetronic
2. 4matic (intel inside)
3. the last one which i assume is the ABS control box.

I have opened up and examined all the boxes and the only thing i am worried about is that the last one which i think is the ABS control module have a smell of that something have been hot in there.
Since i am quite experienced in electronics i visually checked the components but could not find any obvious reason for the smell.
I wonder if the controlbox can be overheated because something draws to much current.
It looks like the box controls the ABS pump motor and the solonoid valve(s).

My next thing to check is the rear diff. ABS sensor but where is the connector ?
Any idea of how similar the voltage from the sensors have to be would be appreciated.
How to properly test the solonoid valve(s)

Of course i can take it to my local professional service but i am not ready to give up yet.(saving my money for a new diesel)


Pelle

300E 4M -89 5 speed