Auto-tranny causing big voltage drop?
Thread Starter
Three Wheelin'
Joined: Apr 2010
Posts: 1,295
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From: Virginia Beach, VA
Auto-tranny causing big voltage drop?
When I put the tranny in reverse or drive, volt meter plunges to 11 volts.
Cleaned up the one ground I could see on the tranny, no joy.
Any advice on rooting out this weird voltage drop?
Btw, RPM's are stable with engagement of drive or reverse.
Cleaned up the one ground I could see on the tranny, no joy.
Any advice on rooting out this weird voltage drop?
Btw, RPM's are stable with engagement of drive or reverse.
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Joined: Jul 2008
Posts: 2,288
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From: NW Arkansas
First guess would be that your alt belt is slipping and not driving the alt fast enough when in gear at idle. Check the accuracy of the gage by checking voltage at the battery, the jump post, and at the connections on top of the CE panel and report back.
Mike
Mike
Three Wheelin'
Joined: Mar 2010
Posts: 1,307
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From: Colorado Springs, CO USA
If you have or can borrow a DVM, it would be good to get independent verification that the voltage is really dropping that much... i.e. that this is not an issue with the voltmeter gauge interacting with the gear indicator display.
Chronic Tool Dropper
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Clean all the grounds.
Clean the positive connctions on the battery itself, plus te ground strap at both ends.
Test the specific gravity of the battery fluid. Replace the battery if low.
Verify that the voltage at the battery is constant, or that it actually varies with the gear selection.
Verify that the voltage at the front jump post is constant, or that it actually varies with the gear selection.
If both are low at idle as you observe on the dash gauge, verify that the alternator belt is tight. Half a belt thickness at mid-span with thumb pressure is pretty darn tight with the thin belt.
If both are still low at idle as you observed on the dash gauge, replace the alternator. Some folks have had success using a common Delco alternator, with a spacer and an adapter for the field connection. I decided that a new Bosch was a better option so I could keep the ventilation hose and hood. It cured the symptoms you describe on my car, after I did all the things I listed above and more. Needle sits just shy of the 14V mark now at idle with fans and lights on, vs the 12 it read prior to replacement.
Clean the positive connctions on the battery itself, plus te ground strap at both ends.
Test the specific gravity of the battery fluid. Replace the battery if low.
Verify that the voltage at the battery is constant, or that it actually varies with the gear selection.
Verify that the voltage at the front jump post is constant, or that it actually varies with the gear selection.
If both are low at idle as you observe on the dash gauge, verify that the alternator belt is tight. Half a belt thickness at mid-span with thumb pressure is pretty darn tight with the thin belt.
If both are still low at idle as you observed on the dash gauge, replace the alternator. Some folks have had success using a common Delco alternator, with a spacer and an adapter for the field connection. I decided that a new Bosch was a better option so I could keep the ventilation hose and hood. It cured the symptoms you describe on my car, after I did all the things I listed above and more. Needle sits just shy of the 14V mark now at idle with fans and lights on, vs the 12 it read prior to replacement.
Thread Starter
Three Wheelin'
Joined: Apr 2010
Posts: 1,295
Likes: 1
From: Virginia Beach, VA
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Thread Starter
Three Wheelin'
Joined: Apr 2010
Posts: 1,295
Likes: 1
From: Virginia Beach, VA
Clean all the grounds.
Done.
Clean the positive connctions on the battery itself, plus te ground strap at both ends.
Done.
Test the specific gravity of the battery fluid. Replace the battery if low.
Brand new battery.
Verify that the voltage at the battery is constant, or that it actually varies with the gear selection.
Will do.
Verify that the voltage at the front jump post is constant, or that it actually varies with the gear selection.
Voltage is constant, but have not checked by changing gear selector.
If both are low at idle as you observe on the dash gauge, verify that the alternator belt is tight. Half a belt thickness at mid-span with thumb pressure is pretty darn tight with the thin belt.
Belt is very tight, and adjuster is maxed out.
If both are still low at idle as you observed on the dash gauge, replace the alternator. Some folks have had success using a common Delco alternator, with a spacer and an adapter for the field connection. I decided that a new Bosch was a better option so I could keep the ventilation hose and hood. It cured the symptoms you describe on my car, after I did all the things I listed above and more. Needle sits just shy of the 14V mark now at idle with fans and lights on, vs the 12 it read prior to replacement.
Done.
Clean the positive connctions on the battery itself, plus te ground strap at both ends.
Done.
Test the specific gravity of the battery fluid. Replace the battery if low.
Brand new battery.
Verify that the voltage at the battery is constant, or that it actually varies with the gear selection.
Will do.
Verify that the voltage at the front jump post is constant, or that it actually varies with the gear selection.
Voltage is constant, but have not checked by changing gear selector.
If both are low at idle as you observe on the dash gauge, verify that the alternator belt is tight. Half a belt thickness at mid-span with thumb pressure is pretty darn tight with the thin belt.
Belt is very tight, and adjuster is maxed out.
If both are still low at idle as you observed on the dash gauge, replace the alternator. Some folks have had success using a common Delco alternator, with a spacer and an adapter for the field connection. I decided that a new Bosch was a better option so I could keep the ventilation hose and hood. It cured the symptoms you describe on my car, after I did all the things I listed above and more. Needle sits just shy of the 14V mark now at idle with fans and lights on, vs the 12 it read prior to replacement.
