400 Cummins Alternater Problem
I just picked up a new alternator motor from freightliner because my light on the dash would not shut off. Long story short the alternator light is right back on with new unit. Called a on the move s...
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Without using a digital voltmeter, we will all be guessing!
With engine off, check voltage at batteries-- both banks. 12.7= fully charged battery.
Start engine. Voltage should rise to 13.5- 14.5 VDC at both batteries.
If not, check at your battery isolator. Both at the lug IN from the alternator and at the lugs OUT to the two battery banks.
Let us know what you find-- if those check out, likely a wiring issue at/to the dash.
Diagnose, don't just replace parts.
And make sure you are NOT on shore power or have the generator on, as that can cause the alternator light to come on.
With engine off, check voltage at batteries-- both banks. 12.7= fully charged battery.
Start engine. Voltage should rise to 13.5- 14.5 VDC at both batteries.
If not, check at your battery isolator. Both at the lug IN from the alternator and at the lugs OUT to the two battery banks.
Let us know what you find-- if those check out, likely a wiring issue at/to the dash.
Diagnose, don't just replace parts.
And make sure you are NOT on shore power or have the generator on, as that can cause the alternator light to come on.
