Why are the lights dimming on my GMC Yukon?

Dimming of the lights is an indication that current is being pulled from the battery. If the battery is in a low state-of-charge (discharged condition), the driver will notice a more pronounced dimming than a vehicle with a fully charged battery. 2.

How does the voltmeter work on a GM Truck?

The charging systems in these vehicles do not use an alternator decoupler to increase gas mileage. Instead they incorporate a Regulated Voltage Control (RVC) system. The RVC is controlled by the PCM and adjusts the amount of “field” to the generator.

When is dimming lights at idle considered normal?

When the vehicle speed is above approximately 24 km/h (15 mph), the engine/generator RPM is high enough and the generator current (amperage) output is sufficient to supply the current (amperage) requirements of the vehicle as originally equipped and recharge the battery. Dimming lights at idle may be considered normal for two reasons: 1.

How to diagnose battery Guage on a GMC Yukon?

The engine computer (ECM/PCM) will ramp up engine/generator speed in small steps so engine speed variations are not noticeable to the driver. For diagnosis of the battery and/or the generator, refer to the appropriate Service Information (SI) or Corporate Bulletin Number 05-06-03-002C.

Why does my GMC Yukon have low voltage?

With the engine running the gauge should measure the output of your alternator. The low voltage may be indicative of issues with your alternator. If you have one of those that shows the voltage without the engine running, then check your gauge for a bad resistor on the dash panel.

When to supplement the battery in a GMC Yukon?

With enough electrical loads “ON”, it is easy to exceed the generator current (amperage) output when the engine is at an idle of 600-700 RPM. This is a normal condition. The battery supplements for short periods of time.

How many volts does a GMC Yukon have?

This is common on large GM Vehicles: Some customers may comment that the voltmeter is fluctuating between 12 and 14 volts on their full size pickup or utility vehicle. Starting with the 2005 model year, light duty full size pickups and utilities are equipped with a new Regulated Voltage Control (RVC) system.

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