Electrical Anomalies '85 528e Lapis Blau

It all started when the Valentine 1 radar detector would inexplicably start stuttering as it started/restarted/restarted. Sometimes it went away and all was fine, sometimes I pulled the power to the V1 and later it was fine.

One day the V1 started chattering, then the console electrics started blinking and flashing, the engine stuttered and, in the confusion I didn't de-clutch, and the car heaved to a stop.

Mechanic says: battery was dead, Coil was "shot" and the speed-sensors (2) were non-functioning: the coil and sensors were replaced and battery was recharged. The car ran normally.

I got a new Mechanic and like the new shop very much, indeed. He replaced the Alternator with voltage regulator, new ground straps (plus and minus at the battery) and in time the low-voltage condition returned intermittently. A second Alternator was installed, with new belts and the two other grounds under the engine were replaced. Car drove fine, but intermittently, the V1 would chatter trying to restart. Car would sit for a couple days and start normally. Had the battery checked and it had good charge and was tested to not be collapsing.

One day I parked the car with the R-Rear door ajar, and didn't go out for 3 days. The battery was completely dead. Got a jump from trusty old AAA and went freeway circling to build up a little charge for the next day's lotta errands 'n such. It was twilight going to evening and all hell broke loose.

Pulling theturn signal/ pull-and-hold-high-beams and the V1 would chatter, the headlights would dim, including the console lights, which all would be modulated, it seemed by the frequency of the V1's chatter - and the charging-icon (far-right) would glow balefuly. After a half minute to a minute, the headlights and console lights would snap to full and all would be OK.

If I pulled on the left-turn signal it would "buzz", or not, but the lights intensity freakout would start all over. Ditto for turning on the fog lights and the high-beams - though not all the time. I drove like this for over 1.5hrs, and parked the car. Immediately restarted the car and got the usual strong starter sound and the car fired up immediately.

Next day took the car to my mechanic and left it with him for over the Thanksgiving Holiday and they could not reproduce the problem. Yes, I left the whole kit of radio, V1 and my cigar lighter interfaces with them - they couldn't reproduce the problem.

I do have the .pdf of the Electrical Troubleshooting Manual for this car. It doesn't really have schematics, per se, but I'm slogging through it to find circuit continuities that connect the left-turn signal, the hi-beam and electrical anomalies on the Cigar lighter, the rechargable battery location that might play with this "Anomaly".

The battery is in good shape, only a few months old and has just been rechecked with new equipment - it's not sagging and did not lose significant charge over a couple of days before Thanksgiving to a day or two after....

An even older anomaly: when engaging the cruise-control for the first time, the low-beam warning light on the Active Check Control lights up. If while continuing driving I turn the key off and back on, repeated turning cruise-controls do not light up the low-beam warning light on the Active Check Control.

Any clues.....?

Thanks for any help,

Vladimir Vooss

I'd be looking at the fusebox, ignition switch, and for corrosion at and in these connectors, and especially inside of the wires that connect the alternator. It's not always visible, but is a known trouble point.

Originally Posted by catso

I'd be looking at the fusebox, ignition switch, and for corrosion at and in these connectors, and especially inside of the wires that connect the alternator. It's not always visible, but is a known trouble point.

Thanks for that!
I'm on back-to-back new alternator replacements and a new ground strap that the alternator connects to.

I'm going to give the fuse-box a thorough cleaning and Deoxit treatment top-side. My brother-in-law, who gave this car to my sister, who later gave it to me mentioned some kind of work some-body did under the fusebox. I don't know what's under there... probably wires, right?

Thanks for the input,

Vladimir