1999 Chevrolet Express Van 1500 alternator won't charge

If there is one, which there may not be, check the battery terminal for a large fuse link.

The voltage regulator is built into the alternator.
https://www.oreillyauto.com/shop/b/charging---starting-4716/voltage-regulator-735/bcb09f5b993f/1999/chevrolet/astro

make sure you didn't leave off a wire

First, you state "the battery is only getting 11.58". This implies the alternator IS charging albeit too low. I would connect the voltmeter to the main terminal on the alternator and take a reading before starting the motor, then again with the motor running at around 1500 RPM (fast idle). This will indicate whether the alternator is working or not.

Getting back to the ign light, does it remain at the same brilliance before starting the engine and after?



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Can't charge a dead battery--- that is due to be replaced

What was tested & how on alternator

Voltage,Current Output ?

Have to have voltage to alternator regulator from where
ever it comes from

If the light is on when car is running, the alternator is still not working. Check your power distribution center near the battery for any fuses out. Maybe there is an alternator fuse.
Is your battery good? A completely dead battery may not take a charge from the alternator. It needs to be charged off the car. Have it load tested at a parts store to see if it's good.
Is your alternator belt tight? A loose belt won't let the alternator work to capacity.

the battery wont stay charged? if youre putting in a fully charged battery and your car runs, but then the battery slowly dies, the problem will be your alternator. the alternator is what maintains a car batteries charge. try replacing the alternator. hope this helps.

It's either your battery or alternator have them tested. If your alternator is bad it wont charge the battery. If the battery is bad it won't hold the charge from the alternator. Good luck!

a bad alternator can over charge as well as under charge - suggest getting a second opinion elsewhere - as far as alternator being "too big" - it will only give the battery what it needs when it is working properly regardless of size

Not enough information. When was the alternator changed and was the battery fully charged before trying to start after installing new alternator. If not the alternator could have burnt up. Have electrical system checked free at Advance Auto.