rphowell

I have a 1992 300E with the 3.0. While driving today I noticed the ABS and SRS lights had come on. Shortly afterwards the car just stop running. I tried to restart and it acted like a dead battery. After waiting for approx. 5 minutes, I tried again and the car restarted. The ABS and SRS lights were off. After 2 miles the lights came on and a mile later the car died. I was beginning to suspect a bad alternator had left me with a dead battery. I called a friend and he jumped the car off after letting it charge for a few minutes. This was enough to get me home where it died again pulling into the garage just after the ABS and SRS lights had come on.

I checked the battery and it was registering 10.5 volts. After sitting for a few minuted the car had enough juice to start. The volts ran down quickly to 9 volts and then the ABS and SRS lights came on. The volts then dropped to 8.5 and the car stalled. I have the battery on charge now.

Is it simply the alternator? It seems strange that the battery light never came on during this ordeal. Only the ABS and SRS lights. Could it be the regulator? How can I check?

Thanks for the advice.

sosh

Could be as minor as a bad battery with an internal short

rphowell

Thanks for your reply. The battery is less than a year old. And aftering charging it is holding a steady 13 volts. I assume that it's the alternator, but was wondering if anyone knew it might be something else or how to test the alternator.

sosh

Any good import auto shop should have a tester for the alternator. Re the battery being only a year old, it could still have a problem even if it holds 13 volts. A loose plate or post connection internally couls cause an intermittent problem particularly with the vibration of the engine running or road vibration. I have had a brand new battery thatbwas intermittent in my boat. Tested fine till it got beat around a little

BensBenz

Rob, I am experiencing the same problems with my 1991 190E 2.3. It died about a week ago in cold weather and would not start at all, so I had it towed to the shop and they replaced the alternator and put a brand new battery in it. This did not solve the problem, because today I got in it, drove approximately 1 hour, and it died on me as I was backing into my parking spot. It is now sitting on the street and will not start, so any info you could send me regarding your fix would be much appreciated.

My suggestion would be not to replace the alternator and battery, but through my extensive research in the past week, I have found that the main culprit is the OVP Relay(Over Voltage Protection Relay). This deprives the aforementioned systems of power, and forces the light to come on.

Please post or inform me of any progress ASAP, as I am having a hard time figuring this problem out as well.

Thanks, -Ben