JustAnswer > Chevy

Chevrolet

Ask a Chevy Question, Get an Answer ASAP!

Have your own Chevy question?

30 Chevy Mechanics are Online Now

characters left:

Not a Chevy Question?

Question

I have a 2003 Chevy Silverado HD and the back door locks will not automaticly lock while driving, with the door lock switch or with the key fob. The front doors lock just fine. I have checked the door lock fuses and I tried replacing the lock relay but this did not help. any suggestions?

Submitted: 1110 days and 3 hours ago.

Category: Chevy

Value: $9

Status: CLOSED

Accepted Answer

You will need to have the BCM (body control module) Scanned for codes. This is the controller for the system and the only thing that GM refers to in the test procedure besides the relay, that you seem to have already eliminated. The only other possibilities would be if both actuators went bad at the same time or if you have a wiring issue. I can send the test procedure if you like.

Expert:	Bob
Pos. Feedback:	99.8 %
Accepts:	2703
Answered:	1/26/2007

Auto Tech

Plus 40 years GM, over 30 certified with Chevrolet, ASE certified Master Tech. (Expired, Retired)

1110 days and 3 hours ago.

Reply

Thanks Bob If you could send the test procedure that would be great. I also forgot to mention that the rear door locks will open just fine but not lock. Thanks again!

Accepted Answer

It is possible that you have an actuator issue. I would check them first. Let me know how it goes and yell if you need something else. Print a copy, note the blue links will not open for you. Good luck.

Power Door Locks Inoperative (Rear Door(s))
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
Activate the front door lock switches to the lock and unlock positions.
Do both rear passenger doors lock and unlock?
Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems
Go to Step 3
3
Is there only one door lock actuator that is inoperative?
Go to Power Door Locks Inoperative - One Door or Switch
Go to Step 4
4
Are the rear door lock actuators inoperative for both lock and unlock?
Go to Step 6
Go to Step 5
5
Do the rear door lock actuators lock?
Go to Step 17
Go to Step 12
6
Is the LOCKS fuse open?
Go to Step 24
Go to Step 7
7
Remove the door unlock relay.
Connect a test lamp to a good ground.
Probe the door unlock relay coil battery supply voltage circuit.
Does the test lamp illuminate?
Go to Step 8
Go to Step 27
8
Connect a test lamp to battery positive voltage.
Probe the door actuator unlock control circuit cavity in the fuse block.
Does the test lamp illuminate?
Go to Step 10
Go to Step 9
9
Install the rear door unlock relay.
Remove the rear door lock relay.
Connect a test lamp to battery positive voltage.
Probe the door lock actuator lock control circuit cavity in the fuse block.
Does the test lamp illuminate?
Go to Step 11
Go to Step 27
10
Connect a test lamp to battery positive voltage.
Probe the rear door unlock relay control circuit.
Does the test lamp illuminate?
Go to Step 22
Go to Step 26
11
Connect a test lamp to battery positive voltage.
Probe the rear door lock relay control circuit.
Does the test lamp illuminate?
Go to Step 23
Go to Step 25
12
Remove the rear door lock relay.
Connect a test lamp to a good ground.
Probe the battery positive voltage circuit (high current) cavity in the fuse block.
Does the test lamp illuminate?
Go to Step 13
Go to Step 27
13
With the test lamp connected to a good ground, probe the lock relay control circuit cavity in the fuse block.
Does the test lamp illuminate?
Go to Step 22
Go to Step 14
14
Connect a test lamp to battery positive voltage.
Probe the lock relay control circuit cavity in the rear fuse block.
Activate a door lock switch to the lock position.
Does the test lamp illuminate?
Go to Step 15
Go to Step 22
15
With the test lamp connected to battery positive voltage, probe the door lock actuator lock control circuit cavity in the fuse block.
Does the test lamp illuminate?
Go to Step 25
Go to Step 16
16
Remove the rear door unlock relay.
With the test lamp connected to battery positive voltage, probe the unlock relay ground circuit cavity in the fuse block.
Does the test lamp illuminate?
Go to Step 26
Go to Step 27
17
Remove the rear door unlock relay.
Connect a test lamp to a good ground.
Probe the battery positive voltage circuit (high current) cavity in the fuse block.
Does the test lamp illuminate?
Go to Step 18
Go to Step 27
18
With the test lamp connected to a good ground, probe the unlock relay control circuit cavity in the fuse block.
Does the test lamp illuminate?
Go to Step 23
Go to Step 19
19
Connect a test lamp to battery positive voltage.
Probe the unlock relay control circuit cavity in the fuse block.
Activate a door lock switch to the unlock position.
Does the test lamp illuminate?
Go to Step 20
Go to Step 23
20
With the test lamp connected to battery positive voltage, probe the door lock actuator unlock control circuit cavity in the rear fuse block.
Does the test lamp illuminate?
Go to Step 25
Go to Step 21
21
Remove the rear door lock relay.
With the test lamp connected to battery positive voltage, probe the lock relay ground circuit cavity in the rear fuse block.
Does the test lamp illuminate?
Go to Step 25
Go to Step 27
22
Test for an open short to ground or short to battery in the door lock relay lock control circuit.
Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 33
Go to Step 28
23
Test for an open short to ground or short to battery in the door unlock relay lock control circuit.
Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 33
Go to Step 28
24
Test for a short to ground in the door lock actuator lock and unlock control circuits.
Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 33
Go to Step 27
25
Inspect for poor connections at the rear door 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 33
Go to Step 29
26
Inspect for poor connections at the rear door unlock 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 33
Go to Step 30
27
Inspect for poor connections at the fuse block. 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 33
Go to Step 31
28
Inspect for poor connections at the harness connector of the body control module. 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 33
Go to Step 32
29
Replace the rear door lock relay.
Did you complete the repair?
Go to Step 33
--
30
Replace the rear door unlock relay.
Did you complete the repair?
Go to Step 33
--
31
Replace the rear fuse block.
Did you complete the repair?
Go to Step 33
--
32
Replace the BCM. Refer to Body Control Module Replacement in Body Control System.
Did you complete the repair?
Go to Step 33
--
33
Operate the system in order to verify the repair.
Did you correct the condition?
System OK
Go to Step 2
Document ID# 903815
2003 Chevrolet Chevy K Silverado - 4WD

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	Activate the front door lock switches to the lock and unlock positions. Do both rear passenger doors lock and unlock?	Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems	Go to Step 3
3	Is there only one door lock actuator that is inoperative?	Go to Power Door Locks Inoperative - One Door or Switch	Go to Step 4
4	Are the rear door lock actuators inoperative for both lock and unlock?	Go to Step 6	Go to Step 5
5	Do the rear door lock actuators lock?	Go to Step 17	Go to Step 12
6	Is the LOCKS fuse open?	Go to Step 24	Go to Step 7
7	Remove the door unlock relay. Connect a test lamp to a good ground. Probe the door unlock relay coil battery supply voltage circuit. Does the test lamp illuminate?	Go to Step 8	Go to Step 27
8	Connect a test lamp to battery positive voltage. Probe the door actuator unlock control circuit cavity in the fuse block. Does the test lamp illuminate?	Go to Step 10	Go to Step 9
9	Install the rear door unlock relay. Remove the rear door lock relay. Connect a test lamp to battery positive voltage. Probe the door lock actuator lock control circuit cavity in the fuse block. Does the test lamp illuminate?	Go to Step 11	Go to Step 27
10	Connect a test lamp to battery positive voltage. Probe the rear door unlock relay control circuit. Does the test lamp illuminate?	Go to Step 22	Go to Step 26
11	Connect a test lamp to battery positive voltage. Probe the rear door lock relay control circuit. Does the test lamp illuminate?	Go to Step 23	Go to Step 25
12	Remove the rear door lock relay. Connect a test lamp to a good ground. Probe the battery positive voltage circuit (high current) cavity in the fuse block. Does the test lamp illuminate?	Go to Step 13	Go to Step 27
13	With the test lamp connected to a good ground, probe the lock relay control circuit cavity in the fuse block. Does the test lamp illuminate?	Go to Step 22	Go to Step 14
14	Connect a test lamp to battery positive voltage. Probe the lock relay control circuit cavity in the rear fuse block. Activate a door lock switch to the lock position. Does the test lamp illuminate?	Go to Step 15	Go to Step 22
15	With the test lamp connected to battery positive voltage, probe the door lock actuator lock control circuit cavity in the fuse block. Does the test lamp illuminate?	Go to Step 25	Go to Step 16
16	Remove the rear door unlock relay. With the test lamp connected to battery positive voltage, probe the unlock relay ground circuit cavity in the fuse block. Does the test lamp illuminate?	Go to Step 26	Go to Step 27
17	Remove the rear door unlock relay. Connect a test lamp to a good ground. Probe the battery positive voltage circuit (high current) cavity in the fuse block. Does the test lamp illuminate?	Go to Step 18	Go to Step 27
18	With the test lamp connected to a good ground, probe the unlock relay control circuit cavity in the fuse block. Does the test lamp illuminate?	Go to Step 23	Go to Step 19
19	Connect a test lamp to battery positive voltage. Probe the unlock relay control circuit cavity in the fuse block. Activate a door lock switch to the unlock position. Does the test lamp illuminate?	Go to Step 20	Go to Step 23
20	With the test lamp connected to battery positive voltage, probe the door lock actuator unlock control circuit cavity in the rear fuse block. Does the test lamp illuminate?	Go to Step 25	Go to Step 21
21	Remove the rear door lock relay. With the test lamp connected to battery positive voltage, probe the lock relay ground circuit cavity in the rear fuse block. Does the test lamp illuminate?	Go to Step 25	Go to Step 27
22	Test for an open short to ground or short to battery in the door lock relay lock control circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 33	Go to Step 28
23	Test for an open short to ground or short to battery in the door unlock relay lock control circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 33	Go to Step 28
24	Test for a short to ground in the door lock actuator lock and unlock control circuits. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 33	Go to Step 27
25	Inspect for poor connections at the rear door 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 33	Go to Step 29
26	Inspect for poor connections at the rear door unlock 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 33	Go to Step 30
27	Inspect for poor connections at the fuse block. 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 33	Go to Step 31
28	Inspect for poor connections at the harness connector of the body control module. 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 33	Go to Step 32
29	Replace the rear door lock relay. Did you complete the repair?	Go to Step 33	--
30	Replace the rear door unlock relay. Did you complete the repair?	Go to Step 33	--
31	Replace the rear fuse block. Did you complete the repair?	Go to Step 33	--
32	Replace the BCM. Refer to Body Control Module Replacement in Body Control System. Did you complete the repair?	Go to Step 33	--
33	Operate the system in order to verify the repair. Did you correct the condition?	System OK	Go to Step 2

Expert:	Bob
Pos. Feedback:	99.8 %
Accepts:	2703
Answered:	1/26/2007

Auto Tech

Plus 40 years GM, over 30 certified with Chevrolet, ASE certified Master Tech. (Expired, Retired)

Chevrolet

Have your own Chevy question?

Related Chevy Topics:

Question

I have a 2003 Chevy Silverado HD and the back door locks will not automaticly lock while driving, with the door lock switch or with the key fob. The front doors lock just fine. I have checked the door lock fuses and I tried replacing the lock relay but this did not help. any suggestions?

Optional Information

Accepted Answer

Reply

Thanks Bob If you could send the test procedure that would be great. I also forgot to mention that the rear door locks will open just fine but not lock. Thanks again!

Accepted Answer

Power Door Locks Inoperative (Rear Door(s))

Chevrolet

Have your own Chevy question?

Related Chevy Topics:

Question

I have a 2003 Chevy Silverado HD and the back door locks will not automaticly lock while driving, with the door lock switch or with the key fob. The front doors lock just fine. I have checked the door lock fuses and I tried replacing the lock relay but this did not help. any suggestions?

Optional Information

Accepted Answer

Reply

Thanks Bob If you could send the test procedure that would be great. I also forgot to mention that the rear door locks will open just fine but not lock. Thanks again!

Accepted Answer

Power Door Locks Inoperative (Rear Door(s))

Related Chevy Questions