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1. How to clear service def system message how to#
2. How to clear service def system message generator#
3. How to clear service def system message manual#

Normal duty cycle for the current sensor is between 5-95%. How long the pulses stay in either ON or OFF position is referred to as pulse-width-modulation, or duty cycle. It converts current measurements into a pulsed 5-volt signal to the BCM. The BCM relies on input from a 3-wire battery 3current sensor.

How to clear service def system message generator#

The body control module (BCM) and engine control module (ECM) communicate with one another over a data buss to determine how much field current to deliver to the generator based on electrical needs and current engine RPM. Knowing this information, EPM can calculate optimum voltage regulation operation to maintain battery voltage, meet the vehicle’s electrical needs, and extend battery life. Once it know initial SOC, it can compute battery needs based on actual current usage, generator output, battery temperature, and battery capacity. It monitors the battery’s state-of-charge (SOC) during ignition off and ignition on cycles by measuring open circuit voltage when the battery hasn’t been used for several hours. So an EPM’s first job is to monitor the condition of the battery and select a charging routine that matches it condition.

How to clear service def system message how to#

But sulfated plates need a special charging technique, and these late model EPM know just how to do that. In the old days, you’d simply slap it on a battery charger. Once battery voltage gets that low, the lead plates can sulfate. However, even if all the computers enter sleep mode, they can still drain a battery to unacceptable low levels in as little as 30 days. To reduce this power consumption when the car is turned off, computers are programmed to go into sleep mode. Late model cars have computers that must remain awake to a certain extent and that means they draw power constantly.

How to clear service def system message manual#

So if you’re working on a late model vehicle with an electrical problem, you darn well better buy a subscription to an up-to-date shop manual like or or you’ll be throwing parts at a problem based on out of date information.Ĭar makers want a charging system to do three things: 1) maintain battery charge above minimum levels, 2) lower fuel consumption when electrical generation isn’t really needed, 3) Get the longest life out of the battery to reduce unnecessary replacement. But GM isn’t the only car maker to use a system like this. I’ll describe GM’s new Electrical Power Management (EPM) system. And the generator is now controlled by several different components.

First off, alternators are now called generators again-even thought they produce alternating current.

Now we’ve entered a whole new realm of power management. Then they decided to let the ECM take over the job of regulating alternator output. When solid state came along, car makers started building the voltage regulator into the alternator. Then car makers switch to an alternator and voltage regulator. In the old days all cars has a generator and a voltage regulator. Service battery charging system message, generator light on, alternator light on, not charging, what does Service battery charging system mean? Make and Model > GMC Trucks > Acadia > Service battery charging… Service battery charging system message Diagnose and fix a service battery charging system message