Hummer H2. Manual — part 309
When the body control module (BCM) receives a signal requesting to illuminate the backup lamps, battery
voltage is sent directly from the BCM through the backup lamp supply voltage circuit to the backup lamps.
Voltage for the backup lamp supply voltage circuit as well as the courtesy lamp supply voltage circuit is from
the left instrument panel fuse block TBC 2B 15-amp fuse directly through the BCM to these circuits.
Conditions for Running the DTC
The battery voltage must be between 9.0-16.0 volts.
Conditions for Setting the DTC
z
When the BCM receives a backup lamp request signal and the backup lamp supply voltage circuit is
shorted to ground.
z
When the BCM is not receiving a backup lamp request signal and the backup lamp supply voltage circuit
is open or shorted to voltage.
z
There is a loss of the instrument panel fuse block TBC 2B battery supply voltage to the BCM for 1
second.
Action Taken When the DTC Sets
The backup lamps 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.
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
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.
2004 Hummer H2
2004 ACCESSORIES & EQUIPMENT Lighting Systems - Hummer H2
DTC B2550
DTC B2575
Step
Action
Yes
No
Schematic Reference: Exterior 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
Backup lamp supply voltage
z
Courtesy 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
4
Test the backup lamp supply voltage circuit for the following
conditions:
z
An open
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
Circuit Description
When the body control module (BCM) senses a request for low beam headlamp illumination, the BCM sends a
ground signal to the low beam headlamp relay through the headlamp low beam relay control circuit. The
headlamp low beam relay will apply voltage to illuminate the headlamps.
Conditions for Running the DTC
The battery voltage must be between 9.0-16.0 volts.
Conditions for Setting the DTC
z
When the BCM receives a command to illuminate the low beam headlamps and the headlamp low beam
relay control circuit is open or shorted to voltage.
z
When the BCM does not receive a command to illuminate the low beam headlamps and the headlamp
low beam relay control circuit is shorted to ground.
z
When the low beam relay coil side is open or the battery positive voltage to the low beam relay is open.
Action Taken When the DTC Sets
The low beam headlamps will not operate or will remain always on.
Conditions for Clearing the MIL/DTC
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 DTC(s) can be cleared using a scan tool.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
3: Tests for voltage at the voltage supply side of the headlamp low beam relay.
4: Verifies that the BCM is providing ground to the headlamp low beam relay.
5: Tests if ground is constantly being applied to the headlamp low beam relay.
6: Tests if there is opposing voltage present or an open headlamp low beam relay control circuit,
including the relay coil side.
12: After replacement of the BCM you must calibrate the new module for proper operation.
DTC B2575
Step
Action
Yes
No
Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics
Connector End View Reference: Lighting Systems Connector End Views or Body Control System
Connector End Views in Body Control System
Did you perform the Lighting Systems
Go to Diagnostic
2004 Hummer H2
2004 ACCESSORIES & EQUIPMENT Lighting Systems - Hummer H2
1
Diagnostic System Check?
Go to Step 2
System Check -
Lighting Systems
2
1. Turn ON the ignition, with the engine
OFF.
2. Place the headlamp switch in the ON
position.
3. Place the headlamp dimmer switch in the
low beam position.
4. Place the headlamp switch in the OFF
position.
Do the low beam headlamps operate as
expected?
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 low beam relay.
3. Turn ON the ignition, with the engine
OFF.
4. Connect a test lamp between the control
circuit of the headlamp low beam relay
and a good ground.
Does the test lamp illuminate?
Go to Step 4
Go to Step 10
4
1. Connect a test lamp between the control
circuit of the headlamp low beam relay
and the battery positive voltage circuit of
the headlamp low beam relay.
2. While observing the test lamp, place the
headlamp switch in the ON position, and
then the OFF position.
Does the test lamp turn ON and OFF with each
cycle of the switch?
Go to Step 8
Go to Step 5
5
Does the test lamp remain illuminated with each
cycle of the switch?
Go to Step 7
Go to Step 6
6
Test the control circuit of the headlamp low
beam relay for a short to voltage or an open.
Refer to Circuit Testing and Wiring Repairs in
Wiring Systems.
Did you find and correct the condition?
Go to Step 13
Go to Step 9
7
Test the control circuit of the headlamp low
beam relay for a short to ground. Refer to
Circuit Testing and Wiring Repairs in Wiring
Systems.
2004 Hummer H2
2004 ACCESSORIES & EQUIPMENT Lighting Systems - Hummer H2
Нет комментариевНе стесняйтесь поделиться с нами вашим ценным мнением.
Текст