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Marblehead
03-03-2010, 07:31 PM
Jittering volt meter…….

Today I noticed a jitter to the volt meter while driving on the highway at constant speed. I’ve read a few other posts regarding electrical issues, I’ve experienced many myself and repair successfully. I’m no dummy but this one has me a bit dumbfounded.

Equipment:
’83 with 6M and newer style, higher amp alternator with necessary resistor mod in the fuse box.

In the past the meter would always do a quick jumping when the turn signal is flashing. Usually a little less than an 1/8 inch jump at the tip of the needle. There’s also been a quick jump whenever applying the breaks. The volt meter does a quick jump and, if on, the lights will do a quick-flip dim.

However, today I noticed the jitter in the volt meter. Traveling on the highway, at constant speed and rpm (@ 3200), the volt meter would randomly jitter, moving the tip of the needle approximately 1/32 inch. The jitter did not have a rhythm, it was random. The road was smooth so it wasn’t jumping due to bumping nor is do I have a thumping stereo. Got to work, idle in the parking lot and the needle is still doing its random jitter. The meter is registering between 12 and 18 volts, normal range that I’ve always seen at speed. The jitter, however is new. At idle it still registers between 12 and 18, closer to 12 as normal. The brake light is not flashing, just a jittery needle. Very slow and random.

Any thoughts? Anyone else experience this anomaly? Possible bad voltage regulator in the alternator? A possible connection to the other event that happened a few weeks ago? As depicted in this topic: http://forums.celicasupra.com/showthread.php?t=54766

The electric slide.
Scott

StanS
03-03-2010, 08:43 PM
loose connection or internall broken wire.

DreadyDiggs
03-04-2010, 12:12 AM
If you really want to test if it's jittering, have someone sit in the car while it's running and watch the needle and you stand at the battery with a multimeter set to Volts DC. Maybe even rev it if you can't get it to do what you want.

Also, if that gauge is reading anywhere near 18 volts and is accurate you have a problem. Alternator output voltage should be no higher than 15.5 volts or you risk overcharging the battery. Yea, bring out the multimeter.

Marblehead
03-04-2010, 11:35 AM
A few other occurrences happened last night when leaving work. Low meter read at idle and a quick flash of the volt light and brake light. Seems the alternator is on its way south. Glad they’re so darn easy to R&R.

StanS
03-04-2010, 01:33 PM
another alt failure symptom I've seen. engine will idle at normal speed but tach will read low.