hey guys, I have a short story today. I was going to work at 7am and while on the offramp turning right the car stalls and refuses to start. luckily, a stranger walking down the street helped me push it into the closest parking lot. so now I look at the instrument cluster for a sign. right before the car quietly died, I saw the srs light come on and then the abs light. when trying to start the car it would do a half ass crank and die again. I thought, it couldn't be charging system because the battery sign on the dash is not illuminated.
I tried a jump start and the car started. not wanting to chance death on the freeway, I got it towed. I jumped it to get it up the driveway and she made it but died where she sits now. after charging, the battery voltage was 13.08 when the car started and stayed at around 12.9 with the motor running. am I right in diagnosing this as a failed alternator? I have not looked at prices yet but the one for the 944 cost a leg, both legs. any help on diagnosis or money saving will be appreciated. thanks for reading my story.

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88 300e
92 mr2

I'd try changing the voltage regulator and brushes before I condemned the alternator. Cost about 25 bux and takes 5 minutes.

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1989 300 SEL that mostly works, but needs TLC

wouldn't a bunk regulator allow the voltage to spike? if the alternator was charging of course. I learned how to check regulators too, my fault for throwing away the handouts. I will try and look it up, I would rather rule out all the possibilities before making any purchase commitments. then again I do need this car running asap.

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88 300e
92 mr2

sounds like its the altnator, you could r&r the voltage regulator and see if its worn down,if it is then repl it, charge the battery, then check the output of the altnator by putting a volt meter across the battery terminals,should be @
13.5 14.7 vdc.

It's usually not the regulator that fails...it's that the brushes wear out. The regulator and brushes come as an assembly.

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1989 300 SEL that mostly works, but needs TLC

After trying 3 different off brand alternators in my '87 300E I finally went to the MB dealer, ordered out a rebuilt factory replacement (not much more than the others). That was two years ago and everything is great. Don't try to save money here. You don't want your family suddenly stopped in the fast lane at 85mph.

I'm kind of a "Basics" guy, by covering the simple first
it can save you time and money. First, the "Battery Light"
on the dash must be working when the key is in the "On"
position. If not check/repalce bulb. Secondly, check all
ground connections for loose fit or corrosion. at the same time,
check the positive cable[s] for the same problems.
While you are at it, check the wires going into the alternator
for corrosion or breakage or improper fit.
In your post you mentioned the light on the dash didn't
appear, that's why I suspect a failed bulb in the dash.
Bosch alternators/starters hold up pretty well, of course with
high mileage anything is able to fail.
Good luck!

I had the same issue with my 90 300E. I replaced the battery since it was about 6 years old anyway and ordered a regulator. Same light issue with the ASR and such but not the battery warning light. Manual says that if it is not charging then the battery warning will come on, but it definately does not on my car and yours either. Cost me 32 bucks for the Bosch from Autohauz. Takes about twenty minutes while in the car. LIke this: Disconnect battery. Jack front of car and place on jack stands. Slide under and remove two screws (phillips head)that attach the regulator and brush assm to alternator and slide out. Wrap new brushes with a strand of dental floss to hold compressed while you insert. Start the two screws and cut and remove the floss. Jack car and remove from stands. Reconnect battery.
Chris
90 300E 132,000m

for all the responses. I didn't know the brushes and regulator came in one kit. I will order this and hopefully this will solve my problem. if not, I will get a dealer rebuilt alternator. thanks again for all your perspectives.

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88 300e
92 mr2

the brushes were worn to hell. after the new regulator the battery voltage reads 15.12 while idling. what a easy fix and $36 bucks. I took the time to change the camshaft seal and timing cover seal as I never get the timing cover sealed right. thanks again for all the responses.

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88 300e
92 mr2

It can also be a bad ground connection from the headlights, or from the engine itself.

just found this. $36 well invested, no probs yet.

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88 300e
92 mr2