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Check engine light/low volts

October 24, 2014, 01:37:37 pm

While going through Nashville on I-24 yesterday check engine light and dinging alarm came on, all gauges read normal except volts was at 12. No way to pull over so I started the gen and hit the boost switch and with in a minute the light and alarm went off.  Continued driving to our destination in Leavenworth IN with gen and boost on, approx 4 more hours without any problems.

Noticed since owning the coach (Aug 2014) under load the Driver Info Center would read 12.3 volts under load and at idle 12.5 volts.  Yesterday it was reading 12.1 at idle and 12 under load.  When I turned on the gen and boost volts remained steady at 13.4 - 13.5.

Not sure what is a normal volt reading when alternator is properly charging but I'm thinking it is going bad.  Three new batteries were installed by FOT when we bought the coach in Aug so I'm ruling out batteries as the problem.  Also, looked at the connections on the alternator posts and they look good.  Should I be looking at something else?

I did have the inverter on yesterday prior to turning on the generator, could that have caused a problem?  Only the refrigerator was on.

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Re: Check engine light/low volts

Reply #1 – October 24, 2014, 01:58:54 pm

Check alternator/belts. Voltage should be somewhere 13.5-14.5 with the main engine running, boost switch off. Double check engine battery terminals also. Would rely on a hand held digital voltmeter for the measurements. Check isolator connections too after the above.

Inverter should be wired into the house batteries so not a problem.

Pierce

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Re: Check engine light/low volts

Reply #2 – October 24, 2014, 02:33:18 pm

I just removed, cleaned applied dielectric grease to every fitting on the isolator board, alternator and chassis batteries. Alternator is more "solid" now right on 14 volts at idle with headlights on. I would begin by checking the sense wire and cleaning all terminals, not hard just a bit time consuming. A Drexel to land wire brush attachment makes this painless.

Roland

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Re: Check engine light/low volts

Reply #3 – October 24, 2014, 10:14:27 pm

I had the same exact problem 3 months ago. It was the alternator. Took it off and carried to repair shop rebuilt it for $200.00. Bearings, voltage regulator etc... Like new. Also replaced battery isolator. They checked it said it was leaking back....another $75.00. Good luck with yours.

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