94 MB E320 wagon bad alternator?

[Shaun @ Tru6]

in NY on business. Was driving from friends in Westchester to the city. thought it odd that the interior lights seemed a little dim, futzed around for the dimmer, didn't register much. no lights lights lit on dash. 10 miles down the road on the Hutch, lights get dimmer and dimmer. 2 miles more and car is dead.

if the Alt light had gone on/been on, would have turned around and taken the train, but clearly the car wasn't charging.

can't remember now if alt/battery light ever lit when key turned on.

thoughts? definitely the alternator? Battery is new, less than 1 year old.

looks like I'm leaving the car here and bringing tools and parts down this weekend.

[Joe Bob]

Charge the battery or replace with known good battery.

Look to see if the alt light comes on, it's part of the charging circuit. If the light is out, could be a bad bulb.

If light comes on, the battery should 12.5-13v at rest, 13 at idle up to 14 at 2500 rpms.

[fastfredracing]

This will be of no help to you, but it is a good little story. I have a customer who is not the sharpest tool in the shed. The alternator went out in his 944 about 7 or 8 hours from home. He bought 4 new batteries, and a battery charger, and drove it home. Took him a couple of days. had to spend the night, and recharge his batteries. An alternator and labor would have been cheaper, and faster

[onewhippedpuppy]

Considering the age of the car, I wouldn't be shocked if the idiot light was burned out. It may not be the only one. Otherwise it sounds like a classic alternator failure.

[Shaun @ Tru6]

Thanks for the replies.

Bit of new info: When it died on the parkway, you could turn the key and the ABS and SRS light (only) would go on. Towed back to my friend's, turn the key with door open, buzzer on, ABS, SRS lights on, no other lights. I went back to the car last night before coming back to Boston and it was stone cold dead. nothing. no lights, buzzer, nothing.

going down on Saturday with an alternator and battery out of the 86, to at least get it back here.

[kaisen]

Shaun, it sure sounds like an alternator (or related)

Good luck, and let us know what it turns out to be

[Ferrariguyma]

The Defect...
Mercedes-Benz made an engineering blunder of gigantic proportions when it decided to use an inferior and unsuitable material for the insulation on the electrical wires of their vehicles. This insulation prematurely disintegrates under normal use causing the wires it is designed to protect and insulate, to short causing many problems. The company continued using used this unsuitable material for many years, even on replacements and repairs. It is not yet known how many vehicles are affected, but it is estimated the number exceeds 1.5 million vehicles manufactured after 1991. It is not a matter of IF the insulation will fail, but of WHEN.

The engine Harness and how a simple harness can kill people...

This harness contains hundreds of wires bundled inside tightly wrapped tape. The wires communicate information from the many sensors of the vehicle’s engine and accessories back to the computer modules. The modules use this information to regulate critical functions such as engine idle speeds, RPM, fuel mixture, fuel injection, ignition and many more..
When the information received by these computers is garbled or erroneous the engine will run rough, accelerate unexpectedly or quit altogether. In addition when the wires short it could cause engine fires, sudden stalls on the highway and other failures that could cause death or serious injury.

Repairing these defects have been a bonanza to Mercedes Dealers, the typical cost of a harness exceeds $2,500, in many cases much more due to collateral damage (see below)... Most of the “repairs” were made with the same defective wires, so a few years later the failures reappear. Innocent victims have forked hundreds of millions of dollars to repair a safety defect that should have been covered by the company that created the problem, erroneously thinking that if the vehicle is out of warranty. Mercedes, aware of the seriousness of the problem, selectively and quietly replaced the harnesses at no cost only to the loudest complainers. They refused to effect a safety recall presumably due to the huge number of vehicles affected.

It gets better...
To add insult to the injury, the very dangerous safety defect also causes collateral damage in other parts of the engines. The expenses of there repairs may exceed the value of the vehicle. The collateral damage extends to very expensive and critical components of the vehicle such as the various computer modules and ECU’s (Electronic Control Units) that regulate the engine’s operation and the microprocessor-controlled fuel injection system, including the PMS (Pressurized Engine Control) Control Unit, the Engine System Power Control Unit, The HFM (Hot Film Air Mass Sensor) control unit and many others. Replacing these modules cost in excess of $10,000 in many cases. The computer modules get fatally damaged by the shorted wires in the harness.

In effect, the vehicle self-destructs.
The question is not one of IF they will fail but of WHEN – All vehicles manufactured in those years (at least ’91-’96) have the defective insulation and will fail sooner or later.

[304065]

Classic alternator failure. Don't know why you didn't get the low voltage light. What neighborhood is the car parked?

[Shaun @ Tru6]

Currently in Pound Ridge, John. My friend Chris is driving me down on Saturday and with any luck, 2 cars will be driving back.

[Tobra]

maybe take a tow strap, just in case

what is the deal with the stuff ferrariguy is talking about?

[Shaun @ Tru6]

Friend in Pound Ridge just sent these pics. Kind of blurry, but they show the positive battery cable fried. We're all set to go down tomorrow with 2 alternators (replacement is by visual inspection) but these pics make me think towing it up is a better option. I'm guessing the voltage regulator went in the alternator and sent too much current to the battery as to why they fried up.

[Tobra]

Trippy, leaky battery maybe trashed it out.

Does the battery tray look like something from a 914?

[Shaun @ Tru6]

I think the voltage regulator died and sent way too many electrons to the battery.

[Shaun @ Tru6]

it does start and run fine with charge/start on a battery charger. so with a battery and alt installed, I think we'll be OK.

[Shaun @ Tru6]

got to the car yesterday, found the alt was putting out 13V with no other electrical running so we put the Carrera battery in and drove back with no drama.

Original MB-Bosch was in the car. Just got the new alternator in: 14.4V goodness.

Want to redo some of the battery wiring, but it's OK for now.