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Alternator Amps and electrical issues question

sdigs

NAXJA Forum User
94 xj, 4.0, AW-4, 4wd with NP-231.

I have posted before about this but have done some searching since and now i have more questions. My tach, speedo and gas gauge stopped working recently. I have searched the harness for shorts, checked all fuses and evev swapped in another gauge cluster. No change.

Someone mentioned the alternator possibly being bad so i had it checked at Vatozone. It is putting out 14+ volts at idle but only 45 amps. I have noticed that it seems to take a few extra seconds of cranking to start lately. The CPS and coil are both new in the last 2 months.

Could low alternator amperage be causing my gauge problem? I know the stock alternator is rated for 90 amps. I assume that 45 indicates an alternator that will likely fail soon. How much of a cast iron Biotch is it replace?
 
"Could low alternator amperage be causing my gauge problem?" No

With the key on and engine off your gauges should still work off of the battery alone. Gauges are not a high amp draw.
 
I agree with Turtle and Shorty, you need to look further.
 
I have posted before about this but have done some searching since and now i have more questions. My tach, speedo and gas gauge stopped working recently. I have searched the harness for shorts, checked all fuses and evev swapped in another gauge cluster. No change.

Since all three of those gauges have inputs from different sources, that should be a clue.

I'd strongly suspect a bad ground. That would be a single point of failure for multiple items.

Otherwise I'd look for physical issues affecting multiple conductors in the harness. Connector corrosion, eg. I've found a few spots where my harness had rubbed enough over it's 20 year 210k lifetime to wear clean through the split loom and wire insulation. Or something cutting it. Or melting it. Or water in a connector.

Do you have full schematics for your year? If so you should be able to physically inspect every inch of the wiring for problems, or find where all three of those gauges share a common ground, etc.
 
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