Some other Areas to check.... (Charging system Question)

[ComancheKid45]

Alright, well tonight i just replaced my alternator with a 105amp Delco Remmy from Advance Auto. I changed it in suspicision of a failing Alt. due to low a Voltage gauge and dimming lights at stop signs/ traffic lights while idling and on the brakes. Upon test driving after the new alternator install I noticed that every once in a while (only happened twice) after a bump the gauge will drop into the red, lights all dim for a few seconds then resume. I Checked the connections at the battery, both connections at the Alternator and the belt tension. I also took off the group of eyelets and cleaned all of them and re installed. Battery was replaced in August of 2009. Even after all this my voltage guage still remains at just above the "low" safe mark but my lights no longer dim at idle and on the brakes. I guess the guage is just out of wack since with a Multimeter on the battery under idle conditions with no loads I'm pulling 14.7 volts. Also the Battery cables still seem in good shape with no signs of rubbing through or issues.

 

Anyway, just seeing if theres anything else i should keep an eye on or check out, over the next few days. Thanks for any info! :thumbsup:

[HOrnbrod]

I think you're golden. As long as you read correct charging voltage at 1K RPM+ across the battery with a known accurate multimeter, I wouldn't worry about it. The OEM dash volt meter is the most inaccurate of all the gauges in the cluster. I've calibrated my own and many others, but with full load (headlamps, both fans, HI blower, etc.) I still dip below midrange, but when checking w. my standard meter it's fine. A lot of it has to do with where the dash voltmeter picks up it's sensing; it was changed throughout the years. As long as your cables are in good shape, all connections are corrosion-free, and all the grounds ((batt, fenderwell, firewall, and engine block) and good, you are good. :D

[holeski]

I have been having that same issue for the last year or so, pulled and checked everything time after time, with no to very little change. An just like you when checking across the battery everything is fine. It's more annoying as anything, I get worried since I'm so use to my YJ dash readings and I forget the MJ is off.

 

hornbrod you said you have calibrated your own, is this something you can do with the stock cluster gages?

[HOrnbrod]

Yes, they can all be bench calibrated. But you need test equipment. For the voltmeter, it uses a calibration resistor across the meter movement. For this you need a decade resistance box to dial it in. Most of the others have a pot you can dial in, but still specialized test equipment is required. And bench testing still isn't accurate in the real world unless all the wiring from the sensor/pickup point is corrosion free and doesn't have voltage drops. It's a major PITA with these old trucks. I don't do it anymore for that reason.