Alternator/Electrical problem
#1
11-27-2005, 10:02 PM
Alternator/Electrical problem
Hi Folks!
My name is Ed and I am a newbie.I just bought a 1993 190e and have,or I should say it has a few problems.I seem to have a relay or altenator problem.The alt output is only 30 something amps,it is a 70 amp alt. The batt is on the charger now.The indications are as follows:After starting There are numerous indicator lights that stay on for a prolonged time like the batt lightn,brake,abs,O2 sensor,these lights are on as well as the others you would normally see on when one turns on the key and before start. After driving for 3 or 4 miles at normal driving speeds the lights go off then come back on then off and on finally the lights will go off and maybe come back on ocasionally for a few seconds randomly.Oh yes theres one other annomally,the Tachometer sometimes drops to zero even though the engine is above idle RPM.Any one out there in MB world have any expert knowledge on these kind of electrical Poltergeists. u009374
My name is Ed and I am a newbie.I just bought a 1993 190e and have,or I should say it has a few problems.I seem to have a relay or altenator problem.The alt output is only 30 something amps,it is a 70 amp alt. The batt is on the charger now.The indications are as follows:After starting There are numerous indicator lights that stay on for a prolonged time like the batt lightn,brake,abs,O2 sensor,these lights are on as well as the others you would normally see on when one turns on the key and before start. After driving for 3 or 4 miles at normal driving speeds the lights go off then come back on then off and on finally the lights will go off and maybe come back on ocasionally for a few seconds randomly.Oh yes theres one other annomally,the Tachometer sometimes drops to zero even though the engine is above idle RPM.Any one out there in MB world have any expert knowledge on these kind of electrical Poltergeists. u009374
#2
11-28-2005, 04:21 AM
RE: Alternator/Electrical problem
Hi Ed,
You have decided that the alternator is bad. You don't state exactly how you came to this conclusion but it sounds plausible since the various warning lights that display are most likely signalling "low voltage".
Each system e.g. ABS, ASR carries out a series of checks (just like a computer when you boot it) and one of these is Voltage since it is fundamental to the working of the ECU / System.
It appears that r alternator is putting out something but only at moderate road speeds is it generating sufficient to maintain the minimum system voltage.
Not sure whether your problem is alternator or conrol circuit. Suspect both of these are quite expensive so make sure you don't get stung for both, when all likelyhood is that only one is bad.
Stuart
You have decided that the alternator is bad. You don't state exactly how you came to this conclusion but it sounds plausible since the various warning lights that display are most likely signalling "low voltage".
Each system e.g. ABS, ASR carries out a series of checks (just like a computer when you boot it) and one of these is Voltage since it is fundamental to the working of the ECU / System.
It appears that r alternator is putting out something but only at moderate road speeds is it generating sufficient to maintain the minimum system voltage.
Not sure whether your problem is alternator or conrol circuit. Suspect both of these are quite expensive so make sure you don't get stung for both, when all likelyhood is that only one is bad.
Stuart
#3
11-28-2005, 11:34 AM
RE: Alternator/Electrical problem
Hi Ed and welcome to the forum.
A few basic tests you can do are.
Take a multimeter and place it accross the plus and minus terminals - that reading should be around 12.5 DC volts -- if this is under 12 DC volts you may have a bad cell -- charge the battery and try again. If it doesn't come up to 12.5 DC volts fairly quickly, you have a bad cell and continuing to charge it will not help. A good thing to do would be to have the Battery tested -- if you can get it somewhere to do so.
A quick and dirty Alternator Test:
With the battery installed:
Start the car and connect the meter again to the plus and minus terminals - you should now be reading approx. 13.5 DC volts to 14.5 DC volts.
Next keep the meter on the terminals and try to hold the RPMs to around 2,000 for around 3-4 min.(or until you get a good reading) - the reading then should stay above approx. 13 DC volts
Hope this helps
A few basic tests you can do are.
Take a multimeter and place it accross the plus and minus terminals - that reading should be around 12.5 DC volts -- if this is under 12 DC volts you may have a bad cell -- charge the battery and try again. If it doesn't come up to 12.5 DC volts fairly quickly, you have a bad cell and continuing to charge it will not help. A good thing to do would be to have the Battery tested -- if you can get it somewhere to do so.
A quick and dirty Alternator Test:
With the battery installed:
Start the car and connect the meter again to the plus and minus terminals - you should now be reading approx. 13.5 DC volts to 14.5 DC volts.
Next keep the meter on the terminals and try to hold the RPMs to around 2,000 for around 3-4 min.(or until you get a good reading) - the reading then should stay above approx. 13 DC volts
Hope this helps
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