Hummer H3. Manual — part 1408

lamps supply voltage circuit is shorted to voltage

Action Taken When the DTC Sets

The I/P controls illumination lamps will not operate or are always ON.

Conditions for Clearing the MIL/DTC

This DTC will clear on current status after the condition for setting the fault is corrected.

A history DTC will clear after 100 consecutive ignition cycles without a fault present.

History and current DTCs can be cleared using a scan tool.

Diagnostic Aids

Perform a visual inspection for loose or poor connections at all related components. Refer to
Testing for Intermittent Conditions and Poor Connections .

Test Description

The numbers below refer to the step numbers on the diagnostic table.

2: This step determines by process of elimination which, if any, dimmable component is
causing the DTC to set.

3: This step determines if the problem exists in the wiring or the BCM.

5: After replacement of the BCM, you must calibrate the new module for proper operation.

DTC B2622 or B2623

Step

Action

Yes

No

Schematic Reference: Interior Lights Dimming Schematics
Connector End View Reference: Lighting Systems Connector End Views or Data
Communication Connector End Views

1

Did you perform the Diagnostic System
Check - Vehicle?

Go to Step 2

Go to

Diagnostic

System Check -

Vehicle

1. Clear the DTC B2622 or B2623

with the scan tool.

2. Turn the park lamps ON.

3. Adjust the instrument panel (I/P)

dimmer switch to a mid-range

2007 Hummer H3

2007 ACCESSORIES & EQUIPMENT Lighting - H3

2

dimming position.

4. Disconnect each dimmable

component from the instrument
panel lamps dimming control
circuit, one at a time, while
monitoring the scan tool current
codes.

Does either DTC not reset after a
particular dimmable component was
disconnected?

Go to Step 4

Go to Step 3

3

Test for one of the following conditions.
Refer to Circuit Testing and Wiring
Repairs .

A short to voltage or short to
ground in the I/P lamps supply
voltage circuit.

An open, high resistance or short to
ground in the park lamp supply
voltage circuit.

Did you find and correct the condition?

Go to Step 6

Go to Step 5

4

Replace the dimmable component
associated with when the code did not
reset. Refer to the proper replacement
procedure for that particular component.
Did you complete the repair?

Go to Step 6

-

5

Replace the body control module
(BCM). Refer to Control Module
References for replacement, setup and
programming.
Did you complete the replacement?

Go to Step 6

-

6

1. Use the scan tool in order to clear

the DTCs.

2. Operate the vehicle within the

Conditions for Running the DTC as

2007 Hummer H3

2007 ACCESSORIES & EQUIPMENT Lighting - H3

DTC B2624

Circuit Description

The body control module (BCM) directly sends a reference voltage to the instrument panel (I/P)
dimmer switch which is then reduced based on the I/P dimmer switch position and monitored as a
signal to the BCM. The BCM uses this signal to directly control the desired level of I/P
illumination lamp intensity.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC 2624 Dimming Display Pulse Width Modulation (PWM) Input Circuit Open

Conditions for Running the DTC

The battery voltage must be between 9-16 volts.

Conditions for Setting the DTC

When the BCM monitors a signal voltage equal to or greater than 4.86 volts for more than one
second

Action Taken When the DTC Sets

The I/P illumination lamp dimming will not operate.

Conditions for Clearing the MIL/DTC

This DTC will clear on current status after the condition for setting the fault is corrected.

A history DTC will clear after 100 consecutive ignition cycles without a fault present.

History and current DTCs can be cleared using a scan tool.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

3: This step tests for the proper operation of the circuit in the low voltage range.

specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK

2007 Hummer H3

2007 ACCESSORIES & EQUIPMENT Lighting - H3

4: This step tests for the proper operation of the circuit in the high voltage range. If the fuse
in the jumper opens when you perform this test, the signal circuit is shorted to voltage.

5: This step tests for a short to voltage in the signal circuit.

6: This step tests for a high resistance or an open in the low reference circuit.

DTC B2624

Step

Action

Value(s)

Yes

No

Schematic Reference: Interior Lights Dimming Schematics
Connector End View Reference: Lighting Systems Connector End Views or Data
Communication Connector End Views

1

Did you perform the
Diagnostic System Check -
Vehicle?

-

Go to Step 2

Go to

Diagnostic

System

Check -

Vehicle

2

1. Install a scan tool.

2. Turn ON the ignition,

with the engine OFF.

3. With the scan tool,

observe the Dimming
Potentiometer input data
parameter in the body
control module (BCM)
Data List.

Does the scan tool indicate that
the Dimming Potentiometer
input data parameter is within
the specified range?

0.6-4.5 V

Go to Testing

for

Intermittent

Conditions

and Poor

Connections Go to Step 3

3

1. Turn OFF the ignition.

2. Disconnect the headlamp

and panel dimmer switch.

3. Turn ON the ignition,

with the engine OFF.

4. With a scan tool, observe

the Dimming
Potentiometer input data

4.5 V

2007 Hummer H3

2007 ACCESSORIES & EQUIPMENT Lighting - H3