Custom 3.1 liter V6. I change the alternator and the alternator harness and put a brand new battery my check gages keep coming on why

Might be a bad alternator
Take it out and get the guys from Advance auto or autozone to check it
I’ve seen bad alternators they’re brand new been defective form the store

Did anyone hook up a scan tool an check for DTC'S - diagnostic trouble code's ? Charging system controlled by the PCM - engine computer .

The check gauges warning light means one of the gauges is either below normal or above. Is one of the gauges out of normal range ?

You have a parasitic drain somewhere. We have an almost identical model at work and we have an ignition problem where you can remove the key in accessory position which leaves some of the electronics on and drains the battery. Faulty light switch, interior light left on?

a ha moment interceptor uses the highest out put available if not custom

Hi Arkina, Have the voltage regulator inspected and checked. If that checks out fine, check the earth connections or have someone check for you. If you have a volt test meter, start the engine and connect the meter to the positive and negative battery poles, measuring the output. At idle the alternator should output about twelve to thirteen volts, increasing to about thirteen volts with an increase of engine speed. With lights and heated rear window on the output should be about thirteen and a half to fourteen volts. Regards John

check your starter.....second battery or second alternator?

change fuel filter

check the voltage at the battery terminals
1 - when the engine is off should be 12.1V to 12.5V
2 - when the engine is idling should be 13.5V to 14.2V
3 - when the engine is revved to 2500 revs (approx is good enough)
voltage should be 14V to 14.8V

If 1 is lower, your battery is probably defective and should be tested.
if 2 or 3 is outside the ranges, the alternator is probably faulty.
NOTE The alternator test machines at Autozone etc... do not always diagnose faults. I have returned several that pass on those machines but cause faults on vehicles. especially where overcharging is the problem as those machines do not "accelerate" like a vehicle does. A poor battery could cause your problem as the alternator sometimes cannot provide enough current to maintain a charge and run the vehicle at idle. If putting your headlamps on at idle causes the gages to light the alternator is not keeping up with the charge... hope that helps...

change your battery cables and check all wires on the alternator for loose connections, expecially the grounds.