Hummer H2. Manual - part 641

DTC B3825 

Circuit Description 

The body control module (BCM) internally grounds the liftgate lock relay control circuit for the liftgate lock 
relay when it receives a Class 2 message from the driver door module (DDM), passenger door module (PDM), 
or when a liftgate lock function is activated. When the BCM grounds the liftgate lock relay control circuit the 
liftgate lock relay is energized and locks the liftgate. 

Conditions for Running the DTC 

z

Battery voltage is between 9.0-16.0 volts.  

z

The DTC will set if the liftgate lock function is active or inactive.  

Conditions for Setting the DTC 

The DTC will set if the liftgate lock relay control circuit is shorted to ground or open for more then one second. 

Action Taken When the DTC Sets 

z

If a short to ground is present on the liftgate lock relay control circuit, the liftgate lock relay will be 
energized and the liftgate lock actuator will be held in the lock position and will not unlock.  

z

If an open condition is present on the liftgate lock relay control circuit, the liftgate will unlock but not 
lock.  

z

The BCM will send a Class 2 message to the DIC indicating that a fault has been detected and the DIC 
will display REPLACE LIFTGATE FUSE.  

Conditions for Clearing the DTC 

When the fault is no longer present, the BCM changes the current DTC to a history DTC. The BCM will clear 
the history DTC after 50 fault free ignition cycles. 

Diagnostic Aids 

DTC B3825 will set as current if any of the following conditions are present:

6

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

Go to Step 7

-

7

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 Doors - Hummer H2

  

z

An open ECC fuse  

z

An open or short to ground in the liftgate lock relay battery positive voltage circuit  

z

A faulty liftgate lock relay  

z

An open or short to ground in the liftgate lock relay control circuit  

z

A short to ground in the liftgate lock actuator lock control circuit will open the ECC with a lock 
command  

z

A faulty BCM  

Test Description 

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

2: Command both the Lock and Unlock states. Repeat the commands as necessary.  

3: Tests for voltage at the coil side of the liftgate lock relay. The ECC fuse supplies power to the coil side 
of the liftgate lock relay.  

4: Verifies that the body control module is providing ground to the liftgate lock relay.  

5: Tests if ground is constantly being applied to the liftgate lock relay.  

DTC B3825 

Step

Action

Yes

No

Schematic Reference: Door Lock/Indicator Schematics 
Connector End View Reference: Power Door Systems Connector End Views

1

Did you perform the Door Systems Diagnostic 
System Check?

Go to Step 2

Go to Diagnostic 

System Check - 

Door Systems

2

1. Install a scan tool.  

2. With a scan tool, command the rear doors to 

Lock and Unlock.  

Does the liftgate Lock and Unlock with each 
command?

Go to Testing for 

Intermittent Conditions 

and Poor Connections in 

Wiring Systems

Go to Step 3

3

1. Remove the liftgate lock relay.  

2. Probe the battery positive voltage circuit of 

the liftgate lock relay with a test lamp that is 
connected to a good ground.  

Does the test lamp illuminate?

Go to Step 4

Go to Step 8

4

1. Connect a test lamp between the liftgate lock 

relay control circuit and the battery positive 
voltage circuit of the liftgate lock relay.  

2. With a scan tool, command the rear doors to 

Lock and Unlock.  

 

2004 Hummer H2 

2004 ACCESSORIES & EQUIPMENT Doors - Hummer H2

  

Does the test lamp turn ON and OFF with each 
command?

Go to Step 9

Go to Step 5

5

Does the test lamp remain illuminated without being 
commanded?

Go to Step 7

Go to Step 6

6

Test the liftgate lock relay control circuit of the 
liftgate lock relay for an open. Refer to Circuit 
Testing and Wiring Repairs in Wiring Systems. 
Did you find and correct the condition?

Go to Step 14

Go to Step 10

7

Test the liftgate lock relay control circuit of the 
liftgate lock relay for a short to ground or an open. 
Refer to Circuit Testing and Wiring Repairs in 
Wiring Systems. 
Did you find and correct the condition?

Go to Step 14

Go to Step 10

8

Test for an open or short to ground in the battery 
positive voltage circuit of the liftgate lock relay. 
Refer to Circuit Testing and Wiring Repairs in 
Wiring Systems. 
Did you complete the repair?

Go to Step 14

Go to Step 11

9

Inspect for poor connections at the liftgate lock 
relay. Refer to Testing for Intermittent 
Conditions and Poor Connections and Connector 
Repairs in Wiring Systems. 
Did you find and correct the condition?

Go to Step 13

Go to Step 12

10

Inspect for poor connections at the harness 
connector of the body control module (BCM). Refer 
to Testing for Intermittent Conditions and Poor 
Connections and Connector Repairs in Wiring 
Systems. 
Did you find and correct the condition?

Go to Step 14

Go to Step 13

11

Repair the short to ground in the liftgate lock 
actuator lock control circuit. Refer to Wiring 
Repairs in Wiring Systems. 
Did you complete the repair?

Go to Step 14

-

12

Replace the liftgate lock relay. 
Did you complete the replacement?

Go to Step 14

-

13

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

IMPORTANT:

Perform the set up procedure for the BCM.

Go to Step 14

-

14

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 

 

2004 Hummer H2 

2004 ACCESSORIES & EQUIPMENT Doors - Hummer H2

  

SYMPTOMS - DOORS 

1. Perform the Diagnostic System Check - Door Systems before using the Symptom Tables in order to 

verify that all of the following are true: 

z

There are no DTCs set.  

z

The control module(s) can communicate via the serial data link.  

2. Review the system operation in order to familiarize yourself with the system functions. Refer to the 

following system descriptions: 

z

Power Windows Description and Operation  

z

Power Door Locks Description and Operation  

z

Door Ajar Indicator Description and Operation  

z

Outside Mirror Description and Operation (Power Mirrors) or Outside Mirror Description 
and Operation (Heated Mirrors) or Outside Mirror Description and Operation (Auto Day - 
Night Mirrors)  

Visual/Physical Inspection 

z

Inspect for aftermarket devices which could affect the operation of the power door lock, power window 
and power mirror systems]. Refer to Checking Aftermarket Accessories in Wiring Systems.  

z

Inspect the easily accessible or visible system components for obvious damage or conditions which could 
cause the symptom.  

Intermittent 

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for 
Intermittent Conditions and Poor Connections in Wiring Systems. 

Symptom List 

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom: 

z

Power Windows Inoperative - Express Down Function  

z

Power Windows Inoperative - Lockout Function  

z

Power Window Inoperative - Driver Door  

z

Power Window Inoperative - Passenger Door (Front Door) or Power Window Inoperative - 
Passenger Door (Rear Door(s))  

z

Door Ajar Indicator Malfunction  

supporting text.  

Does the DTC reset?

Go to Step 2

System OK

IMPORTANT: The following steps must be completed before using the symptom tables.

 

2004 Hummer H2 

2004 ACCESSORIES & EQUIPMENT Doors - Hummer H2