Hummer H3. Manual — part 1125

Conditions for Setting the DTC

The difference between the low precision battery voltage circuit reading and the high precision
battery voltage sense circuit reading is greater than or equal to 1 volt for 10 seconds.

Action Taken When the DTC Sets

The generator battery control module will request the driver information center (DIC) message of
the Service Charging System. The battery tell-tale is not turned ON.

The generator battery control module uses the less accurate battery positive voltage circuit for
voltage readings.

Conditions for Clearing the DTC

During the current ignition cycle, the difference between the less precision battery positive
voltage circuit reading and the high precision battery voltage sense circuit reading is less
than 1 volt.

Clear the DTC with a scan tool.

Diagnostic Aids

Recommended action:

Check the Batt + voltage and Batt + sense voltage wires for an open or short low condition.

Check the Batt - ground and Batt - sense ground wires for an open or short high condition.

Clear the codes.

Cycle the ignition.

If a fault condition persists, replace the module.

DTC B1390

IMPORTANT: You must cycle the ignition after clearing the DTC to turn OFF the

DIC message of Service Charging System.

IMPORTANT: You must cycle the ignition after clearing the DTC to turn OFF the

DIC message of Service Charging System.

Step

Action

Values

Yes

No

Schematic Reference: Starting and Charging Schematics

2007 Hummer H3

2007 ENGINE Engine Electrical - H3

Connector End View Reference: Engine Electrical Connector End Views

1

Did you perform the Diagnostic
System Check - Vehicle?

-

Go to Step 2

Go to
Diagnostic
System
Check -
Vehicle

2

With a DMM, measure the voltage
between both the battery positive
voltage circuits of the generator
battery control module and a good
ground. Compare the reading
between circuits.
Is the DMM reading above the
specified value?

1 V

Go to Step 4 Go to Step 3

3

With a DMM connected to a good
battery positive source, test both the
ground circuits of the generator
battery control module. Compare the
reading between circuits.
Is the DMM reading above the
specified value?

1 V

Go to Step 6 Go to Step 4

4

Inspect for poor connections at the
harness connector of the generator
battery control module. Refer to
Testing for Intermittent
Conditions and Poor Connections
and Connector Repairs .
Did you find and correct the
condition?

-

Go to Step 8 Go to Step 5

5

Repair the open or high resistance in
the affected battery positive voltage
circuit.
Did you find and correct the
condition?

-

Go to Step 8 Go to Step 7

6

Repair the open or high resistance in
the affected generator battery control
module ground circuit.
Did you find and correct the
condition?

-

Go to Step 8 Go to Step 7

2007 Hummer H3

2007 ENGINE Engine Electrical - H3

DTC B1487

Circuit Description

The generator battery control module controls the generator through the generator turn on signal
circuit. The signal is a 5-volt pulse width modulation (PWM) signal of 128 Hz with a duty cycle
of 0-100 percent. Normal duty cycle is between 5-95 percent. If the generator turn on signal
circuit is in the 0-5 percent range, pulled low to ground or open then DTC B1487 will set.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B1487 Generator L-Terminal Circuit Low

Conditions for Running the DTC

The engine speed is greater than 450 RPM.

This diagnostic shall be run every 100 ms.

Conditions for Setting the DTC

The generator turn on signal circuit is less than or equal to 5 percent duty cycle for more than 120
seconds.

Action Taken When the DTC Sets

The generator battery control module will request the driver information center (DIC) message of

7

Replace the generator battery control
module. Refer to Control Module
References for replacement, setup
and programming.
Did you complete the replacement?

-

Go to Step 8

-

8

1. Use the scan tool in order to

clear the DTC.

2. Operate the vehicle within the

Conditions for Running the
DTC, as specified in the
supporting text.

Does the DTC reset?

-

Go to Step 2 System OK

2007 Hummer H3

2007 ENGINE Engine Electrical - H3

Charging System Failure and commands ON the Battery indicator.

Conditions for Clearing the DTC

The generator turn on signal circuit input is from 1-99 percent duty cycle, greater than 0
volts.

Clear the DTC with a scan tool.

Diagnostic Aids

Recommended Action:

Correct L-Term short low condition

Clear the codes.

Cycle the ignition.

If a fault condition persists, replace the module.

DTC B1487

IMPORTANT: You must cycle the ignition after clearing the DTC to turn OFF the

DIC message of Service Charging System.

IMPORTANT: You must cycle the ignition after clearing the DTC to turn OFF the

DIC message of Charging System Failure and turn OFF the
battery indicator.

Step

Action

Values

Yes

No

Schematic Reference: Starting and Charging Schematics
Connector End View Reference: Engine Electrical Connector End Views

1

Did you perform the Diagnostic
System Check - Vehicle?

-

Go to Step 2

Go to
Diagnostic
System
Check -
Vehicle

2

1. Turn ON the engine.

2. With a DMM test the generator

turn on signal circuit of the
generator battery control
module.

0 V

2007 Hummer H3

2007 ENGINE Engine Electrical - H3