I have an 03 chevy 4dr swb. My problem is when I try to lock my doors with the remote or the switch the rear doors wont lock. Every once in a while they will work, but not very often. They unlock just fine, but they wont lock. Has anyone heard of this? Is this a common problem? Where should I start looking for the problem? Any advice would be helpful. Thank you.

Does it do it from either lock switch and the remotes? Or just one of the ways to lock them? Not a common problem.

It happens when you try to lock it from either way remote, or switch.

Power Door Locks Inoperative (Rear Door(s))

<TABLE width="100%" border=1><TBODY><TR><TH vAlign=bottom align=middle>Step

</TH><TH vAlign=bottom align=middle>Action

</TH><TH vAlign=bottom align=middle>Yes

</TH><TH vAlign=bottom align=middle>No

</TH></TR><TR><TD vAlign=top align=left colSpan=4>Schematic Reference: Door Lock/Indicator Schematics (http://service.gm.com/servlets/CellHandler?CellId=11283&RefDoc=903815&evc=sm)

Connector End View Reference: Power Door Systems Connector End Views (http://service.gm.com/servlets/CellHandler?CellId=11706&RefDoc=903815&evc=sm)

</TD></TR><TR><TD vAlign=center align=middle>1

</TD><TD vAlign=top align=left>Did you perform the Door Systems Diagnostic System Check?

</TD><TD vAlign=bottom align=middle>Go to Step 2 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S02)

</TD><TD vAlign=bottom align=middle>Go to Diagnostic System Check - Door Systems (http://service.gm.com/servlets/CellHandler?CellId=12131&RefDoc=903815&evc=sm)

</TD></TR><TR><TD vAlign=center align=middle>2

</TD><TD vAlign=top align=left>Activate the front door lock switches to the lock and unlock positions.

Do both rear passenger doors lock and unlock?

</TD><TD vAlign=bottom align=middle>Go to Testing for Intermittent Conditions and Poor Connections (http://service.gm.com/servlets/CellHandler?CellId=62112&RefDoc=903815&evc=sm) in Wiring Systems

</TD><TD vAlign=bottom align=middle>Go to Step 3 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S03)

</TD></TR><TR><TD vAlign=center align=middle>3

</TD><TD vAlign=top align=left>Is there only one door lock actuator that is inoperative?

</TD><TD vAlign=bottom align=middle>Go to Power Door Locks Inoperative - One Door or Switch (http://service.gm.com/servlets/CellHandler?CellId=12301&RefDoc=903815&evc=sm)

</TD><TD vAlign=bottom align=middle>Go to Step 4 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S04)

</TD></TR><TR><TD vAlign=center align=middle>4

</TD><TD vAlign=top align=left>Are the rear door lock actuators inoperative for both lock and unlock?

</TD><TD vAlign=bottom align=middle>Go to Step 6 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S06)

</TD><TD vAlign=bottom align=middle>Go to Step 5 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S05)

</TD></TR><TR><TD vAlign=center align=middle>5

</TD><TD vAlign=top align=left>Do the rear door lock actuators lock?

</TD><TD vAlign=bottom align=middle>Go to Step 17 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S17)

</TD><TD vAlign=bottom align=middle>Go to Step 12 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S12)

</TD></TR><TR><TD vAlign=center align=middle>6

</TD><TD vAlign=top align=left>Is the LOCKS fuse open?

</TD><TD vAlign=bottom align=middle>Go to Step 24 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S24)

</TD><TD vAlign=bottom align=middle>Go to Step 7 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S07)

</TD></TR><TR><TD vAlign=center align=middle>7

</TD><TD vAlign=top align=left><LI type=1>Remove the door unlock relay. <LI type=1>Connect a test lamp to a good ground.
Probe the door unlock relay coil battery supply voltage circuit.
Does the test lamp illuminate?

</TD><TD vAlign=bottom align=middle>Go to Step 8 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S08)

</TD><TD vAlign=bottom align=middle>Go to Step 27 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S27)

</TD></TR><TR><TD vAlign=center align=middle>8

</TD><TD vAlign=top align=left><LI type=1>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?

</TD><TD vAlign=bottom align=middle>Go to Step 10 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S10)

</TD><TD vAlign=bottom align=middle>Go to Step 9 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S09)

</TD></TR><TR><TD vAlign=center align=middle>9

</TD><TD vAlign=top align=left><LI type=1>Install the rear door unlock relay. <LI type=1>Remove the rear door lock relay. <LI type=1>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?

</TD><TD vAlign=bottom align=middle>Go to Step 11 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S11)

</TD><TD vAlign=bottom align=middle>Go to Step 27 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S27)

</TD></TR><TR><TD vAlign=center align=middle>10

</TD><TD><LI type=1>Connect a test lamp to battery positive voltage.
Probe the rear door unlock relay control circuit.
Does the test lamp illuminate?

</TD><TD vAlign=bottom align=middle>Go to Step 22 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S22)

</TD><TD vAlign=bottom align=middle>Go to Step 26 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S26)

</TD></TR><TR><TD vAlign=center align=middle>11

</TD><TD><LI type=1>Connect a test lamp to battery positive voltage.
Probe the rear door lock relay control circuit.
Does the test lamp illuminate?

</TD><TD vAlign=bottom align=middle>Go to Step 23 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S23)

</TD><TD vAlign=bottom align=middle>Go to Step 25 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S25)

</TD></TR><TR><TD vAlign=center align=middle>12

</TD><TD vAlign=top align=left><LI type=1>Remove the rear door lock relay. <LI type=1>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?

</TD><TD vAlign=bottom align=middle>Go to Step 13 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S13)

</TD><TD vAlign=bottom align=middle>Go to Step 27 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S27)

</TD></TR><TR><TD vAlign=center align=middle>13

</TD><TD vAlign=top align=left>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?

</TD><TD vAlign=bottom align=middle>Go to Step 22 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S22)

</TD><TD vAlign=bottom align=middle>Go to Step 14 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S14)

</TD></TR><TR><TD vAlign=center align=middle>14

</TD><TD vAlign=top align=left><LI type=1>Connect a test lamp to battery positive voltage. <LI type=1>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?

</TD><TD vAlign=bottom align=middle>Go to Step 15 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S15)

</TD><TD vAlign=bottom align=middle>Go to Step 22 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S22)

</TD></TR><TR><TD vAlign=center align=middle>15

</TD><TD vAlign=top align=left>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?

</TD><TD vAlign=bottom align=middle>Go to Step 25 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S25)

</TD><TD vAlign=bottom align=middle>Go to Step 16 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S16)

</TD></TR><TR><TD vAlign=center align=middle>16

</TD><TD vAlign=top align=left><LI type=1>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?

</TD><TD vAlign=bottom align=middle>Go to Step 26 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S26)

</TD><TD vAlign=bottom align=middle>Go to Step 27 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S27)

</TD></TR><TR><TD vAlign=center align=middle>17

</TD><TD vAlign=top align=left><LI type=1>Remove the rear door unlock relay. <LI type=1>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?

</TD><TD vAlign=bottom align=middle>Go to Step 18 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S18)

</TD><TD vAlign=bottom align=middle>Go to Step 27 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S27)

</TD></TR><TR><TD vAlign=center align=middle>18

</TD><TD vAlign=top align=left>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?

</TD><TD vAlign=bottom align=middle>Go to Step 23 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S23)

</TD><TD vAlign=bottom align=middle>Go to Step 19 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S19)

</TD></TR><TR><TD vAlign=center align=middle>19

</TD><TD vAlign=top align=left><LI type=1>Connect a test lamp to battery positive voltage. <LI type=1>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?

</TD><TD vAlign=bottom align=middle>Go to Step 20 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S20)

</TD><TD vAlign=bottom align=middle>Go to Step 23 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S23)

</TD></TR><TR><TD vAlign=center align=middle>20

</TD><TD vAlign=top align=left>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?

</TD><TD vAlign=bottom align=middle>Go to Step 25 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S25)

</TD><TD vAlign=bottom align=middle>Go to Step 21 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S21)

</TD></TR><TR><TD vAlign=center align=middle>21

</TD><TD vAlign=top align=left><LI type=1>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?

</TD><TD vAlign=bottom align=middle>Go to Step 25 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S25)

</TD><TD vAlign=bottom align=middle>Go to Step 27 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S27)

</TD></TR><TR><TD vAlign=center align=middle>22

</TD><TD>Test for an open short to ground or short to battery in the door lock relay lock control circuit.

Refer to Circuit Testing (http://service.gm.com/servlets/CellHandler?CellId=62194&RefDoc=903815&evc=sm) and Wiring Repairs (http://service.gm.com/servlets/CellHandler?CellId=61965&RefDoc=903815&evc=sm) in Wiring Systems.

Did you find and correct the condition?

</TD><TD vAlign=bottom align=middle>Go to Step 33 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S33)

</TD><TD vAlign=bottom align=middle>Go to Step 28 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S28)

</TD></TR><TR><TD vAlign=center align=middle>23

</TD><TD>Test for an open short to ground or short to battery in the door unlock relay lock control circuit.

Refer to Circuit Testing (http://service.gm.com/servlets/CellHandler?CellId=62194&RefDoc=903815&evc=sm) and Wiring Repairs (http://service.gm.com/servlets/CellHandler?CellId=61965&RefDoc=903815&evc=sm) in Wiring Systems.

Did you find and correct the condition?

</TD><TD vAlign=bottom align=middle>Go to Step 33 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S33)

</TD><TD vAlign=bottom align=middle>Go to Step 28 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S28)

</TD></TR><TR><TD vAlign=center align=middle>24

</TD><TD>Test for a short to ground in the door lock actuator lock and unlock control circuits.

Refer to Circuit Testing (http://service.gm.com/servlets/CellHandler?CellId=62194&RefDoc=903815&evc=sm) and Wiring Repairs (http://service.gm.com/servlets/CellHandler?CellId=61965&RefDoc=903815&evc=sm) in Wiring Systems.

Did you find and correct the condition?

</TD><TD vAlign=bottom align=middle>Go to Step 33 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S33)

</TD><TD vAlign=bottom align=middle>Go to Step 27 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S27)

</TD></TR><TR><TD vAlign=center align=middle>25

</TD><TD>Inspect for poor connections at the rear door lock relay. Refer to Testing for Intermittent Conditions and Poor Connections (http://service.gm.com/servlets/CellHandler?CellId=62112&RefDoc=903815&evc=sm) and Connector Repairs (http://service.gm.com/servlets/CellHandler?CellId=61973&RefDoc=903815&evc=sm) in Wiring Systems.

Did you find and correct the condition?

</TD><TD vAlign=bottom align=middle>Go to Step 33 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S33)

</TD><TD vAlign=bottom align=middle>Go to Step 29 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S29)

</TD></TR><TR><TD vAlign=center align=middle>26

</TD><TD vAlign=top align=left>Inspect for poor connections at the rear door unlock relay. Refer to Testing for Intermittent Conditions and Poor Connections (http://service.gm.com/servlets/CellHandler?CellId=62112&RefDoc=903815&evc=sm) and Connector Repairs (http://service.gm.com/servlets/CellHandler?CellId=61973&RefDoc=903815&evc=sm) in Wiring Systems.

Did you find and correct the condition?

</TD><TD vAlign=bottom align=middle>Go to Step 33 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S33)

</TD><TD vAlign=bottom align=middle>Go to Step 30 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S30)

</TD></TR><TR><TD vAlign=center align=middle>27

</TD><TD vAlign=top align=left>Inspect for poor connections at the fuse block. Refer to Testing for Intermittent Conditions and Poor Connections (http://service.gm.com/servlets/CellHandler?CellId=62112&RefDoc=903815&evc=sm) and Connector Repairs (http://service.gm.com/servlets/CellHandler?CellId=61973&RefDoc=903815&evc=sm) in Wiring Systems.

Did you find and correct the condition?

</TD><TD vAlign=bottom align=middle>Go to Step 33 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S33)

</TD><TD vAlign=bottom align=middle>Go to Step 31 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S31)

</TD></TR><TR><TD vAlign=center align=middle>28

</TD><TD vAlign=top align=left>Inspect for poor connections at the harness connector of the body control module. Refer to Testing for Intermittent Conditions and Poor Connections (http://service.gm.com/servlets/CellHandler?CellId=62112&RefDoc=903815&evc=sm) and Connector Repairs (http://service.gm.com/servlets/CellHandler?CellId=61973&RefDoc=903815&evc=sm) in Wiring Systems.

Did you find and correct the condition?

</TD><TD vAlign=bottom align=middle>Go to Step 33 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S33)

</TD><TD vAlign=bottom align=middle>Go to Step 32 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S32)

</TD></TR><TR><TD vAlign=center align=middle>29

</TD><TD vAlign=top align=left>Replace the rear door lock relay.

Did you complete the repair?

</TD><TD vAlign=bottom align=middle>Go to Step 33 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S33)

</TD><TD vAlign=bottom align=middle>--

</TD></TR><TR><TD vAlign=center align=middle>30

</TD><TD vAlign=top align=left>Replace the rear door unlock relay.

Did you complete the repair?

</TD><TD vAlign=bottom align=middle>Go to Step 33 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S33)

</TD><TD vAlign=bottom align=middle>--

</TD></TR><TR><TD vAlign=center align=middle>31

</TD><TD vAlign=top align=left>Replace the rear fuse block.

Did you complete the repair?

</TD><TD vAlign=bottom align=middle>Go to Step 33 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S33)

</TD><TD vAlign=bottom align=middle>--

</TD></TR><TR><TD vAlign=center align=middle>32

</TD><TD vAlign=top align=left>Replace the BCM. Refer to Body Control Module Replacement (http://service.gm.com/servlets/CellHandler?CellId=9004&RefDoc=903815&evc=sm) in Body Control System.

Did you complete the repair?

</TD><TD vAlign=bottom align=middle>Go to Step 33 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S33)

</TD><TD vAlign=bottom align=middle>--

</TD></TR><TR><TD vAlign=center align=middle>33

</TD><TD vAlign=top align=left>Operate the system in order to verify the repair.

Did you correct the condition?

</TD><TD vAlign=bottom align=middle>System OK

</TD><TD vAlign=bottom align=middle>Go to Step 2 (http://service.gm.com/servlets/BlobShtml?ShtmlFile=903815&psdid=297&evc=sm#S02)

</TD></TR></TBODY></TABLE>

This will more than likely be huge, can never get them to resize.
http://service.gm.com/engif/000/000/882/882186.gif

And another one

http://service.gm.com/engif/000/000/882/882189.gif

I swaped lock and unlock relays and problem reversed so I need a relay. Thanks so much for all the good help you saved me alot of money and headache. Thanks again.