1990 190E dash lights - PeachParts Mercedes-Benz Forum

lsmalley · #1 08-31-2008, 01:53 AM

when i turn on my car, the lights on the dash come on and stay on while im driving. this has happened to me once before when the alternator went out on me, but when that happened i could feel the car losing power, this time no power is being lost. i checked the battery and it is good. alternator was replaced about 2 mos ago with a brand new one. belt was replaced at the same time. any help would be greatly appreciated.

cdplayer · #2 09-01-2008, 12:14 PM

Hi Lawrence. Problems with the dash lights may be in the rheostat. Turning the knob of the rheostat will dim or brighten the dash lights when it works properly. It's possible yours has shorted out.

Changing the rheostat involves pulling the instrument cluster out(it is pressed into place). Disconnecting the speedometer cable first allows you better access for disconnecting the rest of the plugs to the back of the cluster. Mark each plug wire as you have done before for easy reassembly.

Now with the cluster in hand flip it over and remove a single screw securing the rheostat. With a little effort, pull the rheostat from it's resting place.
Reassemble with new rheostat.

Attached is a sample of what a rheostat looks like

riorust · #3 09-01-2008, 01:08 PM

When you say dash lights are you talking about all of the idiot lights staying on? Or the dash illumination light?

lsmalley · #4 09-01-2008, 03:11 PM

i think i figured it out.....the battery tested good, but the alternator is not putting out enough voltage. had it tested at autozone. when i accelerate to 20 rpm instead of the voltage goes down instead of up..... i think its the voltage or maybe it was something else. anywho, i just had a brand new alternator put in 2 mos ago, what the #@!$&? i will take my car to the mechanic tomorrow and ask him to fix it for me.... i spent like $1400.00 when i had the alternator replaced because he did (and this is how it is written on the statement receipt i have from him):

PULLEY, ALT
PULLEY, A/C (i dont know what this, anybody got a clue?)
TENSIONER PULLEY
BEARING BRACKET
ALTERNATOR
BELT

riorust · #5 09-01-2008, 03:43 PM

I hope your mechanic takes care of you. When my idiot lights came on and stayed on, it turned out a $20.00 voltage regulator fixed the problem (s).

The A/C pulley sounds like an Air Conditioning compressor pulley.

lsmalley · #6 09-01-2008, 04:57 PM

yes! i have had the voltage regulator problem before! it takes literally 5 minutes to fix or replace. i thought about that originally, but wasnt sure. i will take it to him and have him do it however, beause it was done 2 mos ago an i dont wanna void any warranty on it by messing with it. i have a question....ive been driving my car around, i dont seem to be losing any power, ie, headlights dont dim at night, a/c works fine, etc....is my car safe to drive or will it die on me?

riorust · #7 09-01-2008, 06:21 PM

I drove mine for 3 days (in the late fall/early winter, short trips) with all the idiot lights on, then it died right around the corner from my house...all down hill fortunately. I did not notice any lose of power and it always had started very easily. I should mention that changing the VR fixed the problem for a few months before the alternator shaft ate the brushes again. I swapped out the alternator in about 2 hrs myself. I now keep a spare VR in the glove box with a stubby Phillips screwdriver...just in case.

lsmalley · #8 09-01-2008, 07:03 PM

hmmm i hope mine doesnt die on me....if i could just make until tomorrow i should be fine.

riorust · #9 09-01-2008, 10:24 PM

Do you have a battery charger?

lsmalley · #10 09-02-2008, 03:41 AM

no battery charger, but my mechanic is only 1 maybe 2 miles from me......maybe even less, it takes me 3-5 minutes to get to him, i live on the same street as his shop. (how convenient for me). will keep this thread updated of his findings, but im sure its the alternator, according to the guy and his tester at autozone.

lsmalley · #11 09-02-2008, 11:33 PM

so i took my car in to the mechanic that installed the alternator and he said it was fine. he said that there was a huge shortage somewhere and immediately said its about $200.00 to fix!!! what the @!#$% does this sound right? i hate to say it but im not sure im liking this guy so much anymore. the previous owner of the car used him, i used him off and on for 2 years+, but i think that hes not being honest with me. so i told him straight out @#%& that! and i left to go have it immediately tested again......at which autozone....a different one, told me the alternator was bad. what is going on???? so between 3 diferent people saying bad alternator and the one guy that installed it saying its good and that there is a $200!!!! shortage somewhere, i dont know who to believe. that left me with no choice but to contact the mercedes benz stealership at which they wanted $99 to test the battery and alternator! of course i didnt do it, because thats damn near half the price of the alternator. well all in all, the guy that did install it has gauranteed me a 1 year warranty, but only if its bad and he is saying its not bad. my car wasnt losing power, just the barry light came on saying i wasnt getting a charge. anywho, i dont know why or when, but as i was driving to go to class tonight, i notice that the light was no longer saying i wasnt getting a charge. in essence, the problem resolved itself somehow. needless to say, once my alternator warranty is up, i will not be going back to the mechanic, he may have been telling the truth, but i didnt a precciate the way he immediately said that it was a (quote) "HUGE!! Shortage. It's gonna be $200!" i mean wtf?? i was so upset at that because i spent so much money there. place is called Motorwerks located in Palm Springs, Ca. if anyone uses this please please do not continue to do so.

riorust · #12 09-03-2008, 01:17 AM

Hmmm, 2 different AutoZone shops said the alternator was bad and your mechanic said it was a huge short, but the alternator was okay. Obviously AutoZone stays in business selling parts, your mechanic stays in business repairing cars. Did the mechanic test the alternator the same way the AutoZone guys did?

Estimating $200.00 to repair a "huge short" seems a bit suspect to me as shorts can be a real pain to track down and take quite a bit of time. You mentioned the local dealership wanted $99.00 to test the battery and Alternator, and that was almost half the Alternator replacement cost. I wonder what kind of Alternator your mechanic installed for around $200, as a Bosch or Denso rebuilt from FastLane is about $200.00 on its own.

My guess is that Autozone may be correct, and your mechanic may be trying to dodge a warranty job by charging you $200 to replace a shorted Alternator. Since your battery lamp went out, though I doubt the problem fixed itself, you may want to at least look at your voltage regulator for irregular brush wear.

Do you have a voltmeter?

lsmalley · #13 09-03-2008, 03:55 AM

dont have a voltmeter....but i do know how to take the voltage regulator out and look at it.....it takes about 5 mins. i will check tomorrow. however, if-the-no-charge-to-battery-light comes on again, im gonna demand he replace the alternator. will take note of the serial number to make sure he does it too. im in customer service and if we have an unsatisfied customer, we always try to accomodate or reach some sort of compromise. he did not try to work with me only dismessed the issue as a shortage (which i am obviously still fuming about) but i will check the regulator tomorrow.

riorust · #14 09-04-2008, 06:52 PM

How did it go? I was thinking maybe Autozone and your Mechanic may be right.....you could have a shorted alternator.