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Re: [GMCnet] Help near Springfield, MO [message #326576 is a reply to message #326571] Fri, 01 December 2017 10:02 Go to previous messageGo to previous message
emerystora is currently offline  emerystora   United States
Messages: 4442
Registered: January 2004
Karma:
Senior Member
Shut it down! Way to high voltage on the bottom! You’ll ruin your batttery.

Yes, it looks like a bad isolator.

Emery Stora
77 Kingsley
Frederick, CO

> On Dec 1, 2017, at 8:45 AM, Tom Lins wrote:
>
> Tom Lins wrote on Thu, 30 November 2017 18:53
>> Ken Burton wrote on Thu, 30 November 2017 17:33
>>> Tomtom wrote on Thu, 30 November 2017 15:18
>>>> Do you have a hand held voltmeter? If so, I'd check the voltage across the battery and the voltage at the center position of the diode
>>>> isolator pack (I think this is the lead that goes to the alternator). The isolator diodes will give a half a volt or more voltage drop I
>>>> think.
>>>>
>>>> Tom
>>>
>>>
>>> Tom is entirely correct here is some more info.
>>>
>>> Read the voltage at the isolator WITH THE ENGINE RUNNING. Use the aluminum plate that the isolator is mounted on for your negative meter lead
>>> connection. Any cheap volt meter will work. (Harbor Freight, Walmart, Sears, etc.) The center terminal of the isolator should read around 14.7
>>> volts. The top and bottom terminals should read around 14.0 volts.
>>>
>>> If those voltages are correct read the voltage across the battery. It also should be around 14.0 volts.
>>>
>>> Without the above voltage numbers, here are my best guesses.
>>> 1. Loose plug in back of the alternator
>>> 2. Bad replacement alternator.
>>> 3. Bad isolator
>>> 4. Blown fusible link
>>> 5. Blown "GEN" light in the dash causing the alternator not to start. Does the GEN light turn on with the key on and prior to starting?
>>>
>>> Good Luck. The above are just guesses until we get more information.
>>
>> Ken
>>
>> The voltages were all about what you are saying are correct
>> I really think the dash gauge was not wired correctly, The PPO installed CIP deluxe dash
>> the one with the 4 gauges either side of the Speedo and Tach and I am not 100% convinced everything is
>> wired correctly. There are several other switches on the side panel for the 2 large electric fans
>> in front of the radiator and one to trigger the halon fire extinguisher by the engine.
>>
>> He also installed a second air compressor in the Electro Level system that needs to be turned on
>> with a separate switch and it appears to be hooked to the house battery system.
>> The EL system is acting odd and only seems to be able to maintain normal ride height
>> As long as it can do that until we get home I will look at that when we get home.
>>
>> And yes the gen light does come on before you start it.
>
>
>
> Ken
>
> I made a stupid mistake. I measured the voltage with the engine running but forgot I was plugged into shore power
> This morning in daylight I tried again with the coach disconnected with the engine running. Up to running temp and idleing
> the voltage on the isolater are as follows
>
> Top 11.8
> Center 20
> Bottom 19.1
>
> Chassis Battery reads 11.8 from the hot to the plate the isolator is mounted to.
>
> Bad isolator?
>
> --
> Tom Lins
> Elkton, FL
> 77 GM Rear Twin
>
>
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