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Dash voltage gauge
Try this again.
Got a change in the reading on my dash analog voltage gauge and not sure what it means. Had been reading about 27.5 and when I left on a short trip about a week ago, it read about 24.5 and stayed steady there. No warning lights. No performance issues except “resume” function on speed control stopped working and I am still chasing an intermittent AC/high speed fan clutch operation issue. Due to being a longstanding coward, returned bus to shop and drove car.
Chassis batteries going on 5 years so installed new and at same time removed the Delco Remy 26-SI 24-volt alternator and had it tested. It tested fine and testing on the removed batteries showed one of them completely shot. My optimism that the guage would now read to its old value was unfounded. Still at 24.5. Began my very unsophisticated investigation.
With coach running, reading across jumper lugs (and across batteries themselves) = 24.6. Alternator output = nil. Vanner #1: across 24 volt side = 24.6 and across 12 volt side = 12.3. Voltage regulator: gnd to ign – 24.3, gnd to batt = 27.4, gnd to fld = 3.4 (and unsteady). Vanner #2: 27.4 and 14.
So maybe I don’t have a problem but rather an erratic guage. Not sure the above readings are what I should be reading and what that means. Any thoughts? Mike
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13 Replies
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I do not think your gauge is lying. The fact the dash AC cuts out when the gauge goes to zero is confirming you have an intermittent open circuit.
There might be an open circuit or bad connection associated only with the gauge and AC, or it might be affecting other circuits also. The bad news is tracing intermittent power interruptions is about as much fun as poking yourself in the eye with a sharp stick. It is difficult but it has to be done before there is a potential for serious damage.
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If the problem was the Vanner Monitor it would turn on the balance light.
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Hey Patrick,
Have you checked the relay (signal) wire on the alternator? If you have a bad crimp or a loose connection at the alternator you could experience those symptoms.
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Thanks Kyle, I will check that out next time I’m back there. The Vanner is working just like the book says and the balance is perfect.
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Mike, I think the regulator has failed if the alternator is OK.
Use a jumper from a 24V battery post to the field wire and start the engine. You should measure a rise in voltage as soon as the engine is running and if the regulator is bad the voltage will rise uncontrolled so be ready to pull the jumper before it gets past 29 volts.
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No joy. Mike
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Jon: What about the isolator? Could that be the problem?
2000 Featherlite H3-45
2024 Jeep Grand Cherokee
Leesburg, FL -
Mike, be more specific. Are you saying the alternator output is not above 24 volts even with a jumper from batteries to the field?
If that is the case the alternator is not working as it should. Can you elaborate?
1984 96" with 8V92TA
(remodeled Liberty Coach)
Greenwood, MO -
Nil output from alternator with 24 volt jumper in place to the field post. I am beginning to be suspicious of that bench test result. Mike
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That would be my guess also.
If the alternator was functioning, putting power to the field wire would have excited the field and the alternator would have been providing output voltage.
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Thanks. Back to square one. Mike
1999 XLV X-6872, liberty #440 -
Where were you measuring the alternator output? You need to check it at the alternator first, then follow it down line. The alternator may be working but not reaching the battery… Just a thought
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Will close the loop. Always appreciate when others do that so I can benefit from their solution to whatever issue was at hand.
Problem, of course, is that it requires my revealing my stupidity. No surprise to more than a few.
The place that tested the alternator is highly respected here and essentially every shop with an alternator or starter problem goes there. Several told me that if they said it was ok, it is ok. So search, search, search. Finally on about the sixth time I took the output wire off its post, it seemed softer that it should be under its hard rubber covering. So tear it apart and low and behold, the connector that goes over the alternator output post was completely separated from the wire. Not found before due to not being attentive enough. New end placed, hooked back up and problem solved. Even “resume” function works. Probably flopping around giving voltages all over the place. Still scratch my head on why my volt meter didn’t give a reading on the output post but not going to argue with success. Also learned that the voltage regulator for this 26-SI is internal so I was fussing around with 50DN regulator. Pretty simple to match up wires on a trace but took me some time to tumble. Duh. Maybe the flopping around of the connector was screwing up the internal regulator. ???
So there you have it. Dash gauge reads around 27.5 and on to next issue.
Many thanks to all who chimed in. Makes this site great. Mike
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