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'81 Rabbit electrical problem

This car has left me stranded so many times I'm terrified to even take it out on the road. Basically what happens is I'm driving along and all of the sudden the instrument gauges take a nosedive. Within minutes the car's battery is completely dead. If I get a jump, it starts up and the charging system seems fine for another couple days, week, month, etc. Then if does it again. I've replaced all the negative grounds on the car and have had the alternater bench-tested twice with a thumbs up.

Any ideas on how to proceed next ?

chris

Reply to
chris
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Use a voltmeter to the battery, even if you rig it temporarily. A charging battery should measure at least 13.8 volts, and probably more. If you rig something for use inside the car, run two wires to eliminate errors due to voltage drops in the ground system.

Just using a digital voltmeter with your head under the hood thru a start and idle period may show up your problem.

Battery is suspect. Alternator/regulator is suspect. Wiring is suspect.

Note that the voltage from the negative terminal of the battery to the engine should be very low. Something under 0.10 volts while running (more while starting) . Measure it with the engine running. If you read zero, your meter is not sensitive enough for this test, or you are not making good contact.

Reply to
Tom's VR6

From memory under the battery area inside the wiring harness are fusable links. The link would corrode and cause prolems. Check them out.

Reply to
Woodchuck

leaking windshield over the fuse box brings back horrible electrical memories. am parting out a 40k mile 81 rabbit. large rock (attached to a hill) got rf corner, oil pan, pump, and took out the block. located in southern indiana near lou, ky. rick.

Reply to
northwind

I don't know of anything that can cause a car's battery to go dead "in a matter of minutes". I think what must be happening is that the battery is being drained to the point that it causes the gauges to go away and then drains a little more and then the car dies. What is the installed voltmeter doing before/while this is happening?

Steve

Reply to
Stephen Haare

"Stephen Haare" wrote in news: snipped-for-privacy@comcast.com:

Hi Steve,

My '81 doesn't have an installed voltmeter, but it's clear I need one. The last time it happened, I pushed the car a few hundred feet to an independent Honda shop. The mechanic charged the battery for me and then used what I assume was a voltmeter. He said the system was definitely not charging. So if the tested alternater is still good and with the grounds and main alternater wiring leading under the radiater having been replaced, where would you look next ?

Thanks to everyone for their help, btw.

Regards,

Chris

Reply to
chris

Usual questions at this point:

  1. With the engine off; When you turn on ignition - will the alternator light in the dash come on?
  2. After you started the engine - will the alternator light go out by itself, or at least when you rev the engine once?

Ingo

Reply to
Ingo Braune

Ingo Braune wrote in news: snipped-for-privacy@web.de:

Yes, to both questions; the light goes out by itself.

I guess the next step is to get a multi-meter.

Thanks, chris

Reply to
chris

I doubt this is it but on my 85 cabriolet the harness between the alt and battery l;ooked fine but had actually dissolved into fine powder.looked good but once i pulled it apart and replaced.what a difference

chris wrote:

news: snipped-for-privacy@web.de:

alternator

Reply to
vwtopdown

There are really only a few possibilities. The alternator/voltage regulator could be bad. The battery could be bad. Or the wiring between the alternator and the battery is bad.

If you've had the alternator tested (as in taken off the car, put in a test rig and thorougly tested under load), and you've had the battery tested (as in taken out of the car, put in a load test rig and thoroughly tested under load), then that only leaves wiring problems.

It's either the positive wires from the alternator to the battery (the big red wires in the harness under the radiator), or it's the grounds. There should be a ground strap or ground wire of some kind connecting the body of the alternator to the engine, and there is a big ground strap from the transmission mount to the negative battery terminal.

Never connect a small wire from the negative battery terminal to the alternator. If the big ground strap from the transmission bracket fails, that small wire will become the only ground path for the starter, and when you try to crank the car, the little wire will melt and/or catch fire. The only connections between anything on the engine/transmission and the negative battery terminal or body should be large, heavy duty wires (as in battery cable or welding cable large).

-- Racer X

1984 VW Jetta Diesel GT 1992 Mazda Miata (looks OK considering it's been hit by an 18 wheeler) 1994 Caravan (OK, maybe it's a keeper, but I still want a VW Caddy) 1995 Ford Escort (may it rest in pieces) 1983 VW Rabbit GTI (ITB racer) 1988 Mazda RX-7 (maybe for sale, make offer) 1992 GMC Topkick (portable garage for racecar[s])
Reply to
racer_x

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