Synchronized Warning Lights on 911 SC
 

Went for a long hard drive yesterday in the rain. After 90 miles out and only 10 miles from home both the Alternator light and the Oil pressure lights came on in unison for a second. As I came into town they came on again and the car died at a stop light. Got her started and limped her home. The oil was a quart low, but the V-belt seemed tight and the previous owner had the alternator changed 10K miles ago.

Any ideas? I should note that I had the car loaded up rather well because of the rain and cold weather (lights on, windshield wipers on high, as with heat/defrost motors).

At worst, the Voltage Regulator is acting up, but.......................

Go over all ground connections, especially where the negative battery cable connects to the body on the left fender. Open the bolt, clean the ends real well, re-connect using dielectric grease.
Clean the battery posts and connectors, use dielectric grease on the posts.

Inspect the ground strap from the transmission to body, disconnect and re-connect using dielectric grease.

I also lube the 14-pin connector by first disconnecting the battery, then carefully prying open the connector with a screwdriver, lube with dielectric grease.

Did I mention dielectric grease? :D

Check to make sure that the Voltage Regulator (alternator) isn't misbehaving; i.e. overcharging.

That can be VERY expensive. As in FIRE. As in having to replace the entire wiring harness.

That would be the number one thing I would check. Now.

The bad ground won't damage anything.

Not to worry, I'm a big fan of grease myself...

Thanks a lot, I'll look into all that!

tcar...

How might I check to see if the VR is overcharging?

Place a voltmeter accross the battery terminals, start the car, 2000 RPM's.

The voltage should not exceed 14.5 V.

Typical is 13.5-14.0.

Turn on some accessories, lights, A/C ect.. and verify that the voltage stays constant.

Good luck,

Gerry

you may pm me.

Thank you, that's certainly to the point. And if it's over charging??? New alternator? Or something more complicated?

Typically it would be the voltage regulator which, I think, may require the removal of the alternator.

Not certain about your model/year.

Good Luck,

Gerry

Do what 86 911 says.

I think 80 was the last year with a separate voltage regulator, but if it's been replaced, it will have an alternator with a VR that's integral with the alternator. Your 81 should have come with the integral unit.

Our cars do not have Voltmeters, so when it happened to me, I had no idea that it was overcharging, except that I finally smelled the battery, and the wipers turned on high by themselves. Got away fairly cheaply. Had to replace many bulbs, some fuses. CD ignition was OK (whew).

I know someone that had to replace the entire harness on his car - $7,000.

Had an Optima that got so hot it melted the carpet in the trunk, but no acid. The case was very soft and it was almost too hot to touch. Optima's warranty is great - replaced the battery no questions (it was only 15 months old).

I got one of those voltmeters that you plug into the cig lighter and I plug it in briefly at least once every time I drive the car. They're cheap on eBay.

For now, my radar/laser detector displays my voltage at the cig. lighter point. I watch it like a hawk, as I onced experienced voltage spikes and envisioned having to by a new DME....

Should you make use of the cig lighter output for voltage measurement, DO compare your readings at this point with the actual battery posts (as a reference).


Time for an alternator and voltage reg test.

Best,

Doyle