Hummer H2. Manual — part 313

z

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

z

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

z

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

Diagnostic Aids

z

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

z

An open circuit up to the first splice only, from the BCM, will set the DTC.

z

A short to ground on the backup lamp supply voltage circuit, courtesy lamp supply voltage circuit OR the
TBC 2B battery positive voltage circuit to the BCM will open the TBC 2B fuse in the left instrument
panel fuse block.

Test Description

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

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

4: This step test 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 B2615

Step

Action

Yes

No

Schematic Reference: Interior Lights Schematics
Connector End View Reference: Lighting Systems Connector End Views or Body Control System
Connector End Views in Body Control System

1

Did you perform the Lighting System Diagnostic System
Check?

Go to

Step 2

Go to Diagnostic System

Check - Lighting Systems

2

Inspect the TBC 2B fuse in the instrument panel fuse block.
Is the fuse open?

Go to

Step 3

Go to Step 4

3

Test the following circuits for a short to ground. Refer to
Circuit Testing and Wiring Repairs in Wiring Systems:

z

Courtesy lamp supply voltage

z

Backup lamp supply voltage

z

TBC 2B battery positive voltage to the body control
module (BCM)

Did you find and correct the condition?

Go to

Step 6

Go to Step 5

Test the courtesy lamp supply voltage circuit for the
following conditions:

z

An open

2004 Hummer H2

2004 ACCESSORIES & EQUIPMENT Lighting Systems - Hummer H2

DTC B2620

Circuit Description

The BCM directly sends a 5-volt reference voltage to the I/P dimmer switch which is then adjusted based on the
I/P dimmer switch position and returned as a low reference and a signal to the BCM. The BCM uses this signal
to directly control the desired level of instrument panel illumination lamp intensity.

Conditions for Running the DTC

The battery voltage must be between 9.0-16.0 volts.

Conditions for Setting the DTC

z

The BCM monitors a low reference voltage of less than 4.5 volts.

z

The BCM monitors a high reference voltage of greater than 5.5 volts.

z

The BCM monitors a signal voltage of equal or greater than 4.86 volts for more than 1 second.

Action Taken When the DTC Sets

The instrument panel illumination lamp dimming will not operate.

Conditions for Clearing the MIL/DTC

z

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

4

z

A short to voltage

z

High resistance

Refer to Circuit Testing and Wiring Repairs in
Wiring Systems.

Did you find and correct the condition?

Go to

Step 6

Go to Step 5

5

Replace the BCM. Refer to Body Control Module
Replacement in Body Control System.Did you complete the
replacement?

IMPORTANT:

Perform the setup procedure for the BCM.

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 specified in the supporting text.

Does the DTC reset?

Go to

Step 2

System OK

2004 Hummer H2

2004 ACCESSORIES & EQUIPMENT Lighting Systems - Hummer H2

z

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

z

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: Tests for the proper operation of the circuit in the low voltage range.

4: 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 ground.

5: Tests for a short to voltage in the 5-volt reference circuit.

6: Tests for a high resistance or an open in the low reference circuit.

DTC B2620

Step

Action

Value

(s)

Yes

No

Schematic Reference:Interior Lights Dimming Schematics
Connector End View Reference:Lighting Systems Connector End Views or Body Control System
Connector End Views in Body Control System.

1

Did you perform the Lighting Systems
Diagnostic System Check?

-

Go to Step 2

Go to

Diagnostic

System Check -

Lighting

Systems

2

1. Install a scan tool.

2. Turn ON the ignition, with the engine

OFF.

3. With the scan tool, observe the Dimming

Input data parameter in the Body Control
Module Data List.

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

4.5-

5.5 V

Go to Testing for

Intermittent

Conditions and Poor

Connections in Wiring

Systems

Go to Step 3

3

1. Turn OFF the ignition.

2. Disconnect the headlamp switch.

3. Turn ON the ignition, with the engine

OFF.

4. With a scan tool, observe the Dimming

Input data parameter.

Does the scan tool indicate that the Dimming
Input data parameter is less than the specified

4.5 V

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2004 ACCESSORIES & EQUIPMENT Lighting Systems - Hummer H2

value?

Go to Step 4

Go to Step 10

4

1. Turn OFF the ignition.

2. Connect a 3 amp fused jumper wire

between the 5-volt reference circuit of the
I/P dimmer/headlamp switch and the signal
circuit of the I/P dimmer/headlamp switch.

3. Turn ON the ignition, with the engine

OFF.

4. With a scan tool, observe the Dimming

Input data parameter.

Does the scan tool indicate that the Dimming
Input data parameter is greater than the specified
value?

4.86

V

Go to Step 5

Go to Step 8

5

1. Disconnect the fused jumper wire.

2. Measure the voltage between the 5-volt

reference circuit of the I/P
dimmer/headlamp switch and the low
reference circuit of the I/P
dimmer/headlamp switch.

Does the voltage measure less than the specified
value?

5.15

V

Go to Step 6

Go to Step 7

6

1. Turn OFF the ignition.

2. Disconnect the negative battery cable.

Refer to Battery Negative Cable
Disconnect/Connect Procedure (Single
Battery) in Engine Electrical.

3. Measure the resistance from the low

reference circuit of the I/P
dimmer/headlamp switch to a good ground.

Does the resistance measure less than the
specified value?

5 ohm

Go to Step 12

Go to Step 11

7

Test the 5-volt reference circuit of the I/P
dimmer/headlamp switch for a short to voltage.
Refer to Circuit Testing and Wiring Repairs in
Wiring Systems.
Did you find and correct the condition?

-

Go to Step 16

Go to Step 13

8

Test the 5-volt reference circuit of the I/P
dimmer/headlamp switch for a short to ground, a
high resistance, or an open. Refer to Circuit
Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?

-

Go to Step 16

Go to Step 9

2004 Hummer H2

2004 ACCESSORIES & EQUIPMENT Lighting Systems - Hummer H2