Flint

A few times in the last few weeks I've started my car at night and seen the voltage meter drop to about 10. The lights also dim, and the engine seems to run a little rougher. Turning the fan or the radio off don't seem to help, though after driving for a short distance, the needle jumps back up and the lights come on full power and everything is normal. It's as if I had a UFO point some kind of beam at me. The only thing very alarming is that for less than a second, ALL the warning lights flash, but that's just when the power comes back. This particularly concerns me because I had something similar happen just before my alternator went out (almost exactly a year ago). Am I heading toward complete disaster?

Martin

sounds like you have a problem with you engine grounding, check and tighten all your ground points.

Adrian

Dear Flint,
First thing to check is your battery connections. Are they tight. As already suggested check your ground cables. The cable from the battery to where it mounts to the chassis. Check this for tightness and corrosion. The most common cause of your problem is normally the earth cable from the battery or the positive terminal is loose.
If all the mechanicals check out then you have to look at,
Battery,
Alternator/Regulator assembly. Check start votlage with a multimeter not hte indicator inside, should be no less than 10VDC. Check voltage with engine running at 1200RPM, should be no less than 13.8VDC and check voltage after shut down, should be around 12.4VDC.
Starter Solenoid and starter connections
Starter Motor itself
Ciao,
Adrian
911C4

PS: The reason is the warn lights come on is because the voltage supply is too low to activate the control units.

Randy V

Model year?

My guess is a loose alternator belt that slips when cold, then begins grabbing as it warms up.

Reply back with your findings.

Flint

Got caught up in describing the problem, I forgot to say which year it was. It's an 84 Euro, with the dual distributor/coil arrangement. I'll check all those and more (i.e. everything attached to those mentioned that could be drawing off power.) I don't hear any kind of screeching I normall associate with alternator belt slippage, but I'll check just to be sure. Thanks.

Flint, '84 Euro-S, AT

Moss928

Sounds like the alternator to me!

Incendier

When you say "driving a short while", does the alt start charging when you get above a certain RPM, like, say, 3K or so? And does it stay good for the duration of the drive after that?

If so, it sounds like the "alternator failing to excite" problem that Snowy and others were discussing a while ago. If you can give it a very strong throttle kick and it will start charging, there you are.

Two possible things to check if that's the case - first, make sure that the D+ terminal on the alt is connected solidly and to the correct post, and second, check the resistor on the dash panel (in circuit with the alternator gauge). It's necessary to kick-start the alternator into charging.

Good luck...BTDT. Mine was a bad connection at the D+ post.