Strange Onboard voltage pattern
Thread Starter
Newbie
Joined: Aug 2013
Posts: 14
Likes: 0
E220 CDI 2004
Strange Onboard voltage pattern
Okay, so i was driving on the highway yesterday that the Red battery sign with visit workshop error appeared on display. I parked the car on the road side and and switched off the car. Then i opened the voltage display and it was showing 12.7 V for rear battery with car turned off.
Afterwards i turned on the car and the voltage jumped to 13.8. When i start driving, the voltage also starts increasing proportionally from 13 to 17.4 V. At 17 Volts, the ECU shuts off probably due to overvoltage and i get all the errors like ESP, ABS, Braking, etc. I slow the car and all the errors and voltage goes down to 13.8V
Further, this issue is intermittent. Sometimes the voltage stays stable at 13.8 to 14 whereas sometimes it is fluctuating like this. What could be the issue? My guess is that the voltage regulator's terminals connecting with the alternator have some carbon on them and maybe it is working intermittently.
Would love your thoughts on this?
Afterwards i turned on the car and the voltage jumped to 13.8. When i start driving, the voltage also starts increasing proportionally from 13 to 17.4 V. At 17 Volts, the ECU shuts off probably due to overvoltage and i get all the errors like ESP, ABS, Braking, etc. I slow the car and all the errors and voltage goes down to 13.8V
Further, this issue is intermittent. Sometimes the voltage stays stable at 13.8 to 14 whereas sometimes it is fluctuating like this. What could be the issue? My guess is that the voltage regulator's terminals connecting with the alternator have some carbon on them and maybe it is working intermittently.
Would love your thoughts on this?
Thread Starter
Newbie
Joined: Aug 2013
Posts: 14
Likes: 0
E220 CDI 2004
Tried opening the voltage regulator today. Removed the bottom plate and bummer... The back of the generator is at a very tight place for the OM646 diesel engine on my W211. I cannot access the clips with my hands, let alone opening the screws of the voltage regulators.
Can anyone share the WIS document for changing VR or atleast removing the alternator totally?
Can anyone share the WIS document for changing VR or atleast removing the alternator totally?
