PS window, lock, and mirror don't work (it's not the module)
05-24-2011, 04:21 PM
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PS window, lock, and mirror don't work (it's not the module)
It isn't the control module because I switched it with the DS module and the DS works. That is, the drivers side window, lock and mirror work with the PS module, but the PS window, lock and mirror don't work with the DS module. The fuse for the PS door was burned out and I was sure that was the problem, but I replaced it and it still doesn't work. ??? I pulled the accordion boot off and checked continuity on every wire. It's all good. Then there is 12V on the orange wire going into the module.
Codes are: A0-LDCM no comm.
A1-RDCM no codes
And I checked these two both with the modules switched and in their correct place and the codes are the same regardless. LDCM always has no comm. The only other codes are HVAC codes. U1160 HC (which is no comm with LDCM; funny that it's put under HVAC codes) and B0365 H and B0367 H (both H codes come back immediately after reset but the HVAC stuff is a different problem).
Help please.
Codes are: A0-LDCM no comm.
A1-RDCM no codes
And I checked these two both with the modules switched and in their correct place and the codes are the same regardless. LDCM always has no comm. The only other codes are HVAC codes. U1160 HC (which is no comm with LDCM; funny that it's put under HVAC codes) and B0365 H and B0367 H (both H codes come back immediately after reset but the HVAC stuff is a different problem).
Help please.
Last edited by bluemaggot; 05-24-2011 at 04:54 PM.
05-26-2011, 01:54 AM
#3
Did you verify 12V across orange & black, or from Orange to an easier chassis ground?
From GM SI:
If the RH DCM doesn't control the RH window or lock actuator, I believe you don't have a complete circuit (power and ground) to the module.
HVAC Errors (not door lock actuators) -
DTC B0365 Right Actuator Feedback Short to GND
DTC B0367 Right Actuator Feedback Open
I am guessing you have an intermittent or unreliable ground to get both of those errors from the HVAC, along with the DCM.
The diagram shows G202 as the ground point for the RH DCM which is also used for many interior lamps, the cigarette lighter, and the HVAC control module. If those are all working, I suspect the problem is more localized in the accordian area. G202 is at the bottom of the psgr A-pillar. Thanks for the diagram, Lucky!
The connector in the accordian by the hinge often exposes conductors, and is responsible for the OBD bus communication failures like you are seeing (and probably the blown fuse). Bill Curlee is the man - see this thread for pics. May not hurt to reinspect those connectors closely.
The computers all talk between themselves, so the U-code from the HVAC complaining about not seeing the door module makes sense since the BCM can't see it either. The key wires for OBD bus communication of the DCMs are just ground and serial data (tan). You might check continuity of the tan wire back to the star-connector in the foot well.
Hope this helps.
Todd
From GM SI:
The LH window switch circuit provides input to the LH Door Control Module (LDCM) when the LH window switch is pressed. This input allows the LDCM to detect a window UP or DOWN request from the LH window switch. The LDCM provides power and ground to both of the window switches. When the LH window up switch is pressed, a ground is supplied through the LH window up switch to the LDCM window up input which is pulled low. When the LDCM detects low voltage on the LH window up input, the LDCM will command the LH window UP. If the LDCM detects low voltage on the LH window down input, the LDCM will command the LH window DOWN. If the RH window is operated from the LH window switch, the LDCM will send a message on the serial data line to the RH Door Control Module (RDCM) to operate the RH window UP or DOWN. The RH window operates the same as the LH window except the RDCM is receiving the RH window switch input and controlling RH window output functions. The DCMs provide both power and ground through CKT 164 and CKT 165 to the window motors. The up and down output operation is similar to each other except that the polarity of the voltage applied to the window motors is reversed.
The LH door switch circuit provides input to the LH Door Control Module (LDCM) when the switch is pressed to the LOCK or UNLOCK position. This input allows the LDCM to detect a door LOCK or UNLOCK request. The LDCM provides both power and ground to the LH door lock and unlock switches. When the LH door lock switch is pressed, a ground is supplied through the LH door switch to the LH door lock input which is pulled low. When the LDCM detects low voltage on the LH door lock input, the LDCM will LOCK the LH door. The LDCM will also send a message on the serial data line to the RH Door Control Module (RDCM) to LOCK the RH door. When the LH door unlock switch is pressed, the LDCM will UNLOCK the LH door and also send a message on the serial data line to the RDCM to UNLOCK the RH door. The RH door lock and unlock function operates the same as the LH door except when the RDCM detects low voltage on the RH door lock input, the LOCK or UNLOCK message is sent to the LDCM. Both DCMs provide output control to their respective door lock motor based upon a LOCK or UNLOCK switch input or from a message received on the serial data line from the opposite DCM. The DCMs provide both power and ground through CKT 294 and CKT 295 to the door lock motors. The lock and unlock output operation is similar to each other except that the polarity of the voltage applied to the door lock motors is reversed.
HVAC Errors (not door lock actuators) -
DTC B0365 Right Actuator Feedback Short to GND
DTC B0367 Right Actuator Feedback Open
I am guessing you have an intermittent or unreliable ground to get both of those errors from the HVAC, along with the DCM.
The diagram shows G202 as the ground point for the RH DCM which is also used for many interior lamps, the cigarette lighter, and the HVAC control module. If those are all working, I suspect the problem is more localized in the accordian area. G202 is at the bottom of the psgr A-pillar. Thanks for the diagram, Lucky!
The connector in the accordian by the hinge often exposes conductors, and is responsible for the OBD bus communication failures like you are seeing (and probably the blown fuse). Bill Curlee is the man - see this thread for pics. May not hurt to reinspect those connectors closely.
The computers all talk between themselves, so the U-code from the HVAC complaining about not seeing the door module makes sense since the BCM can't see it either. The key wires for OBD bus communication of the DCMs are just ground and serial data (tan). You might check continuity of the tan wire back to the star-connector in the foot well.
Hope this helps.
Todd
05-26-2011, 10:07 PM
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Thanks Todd. I looked at some more things, and as it ends up, I'm ashamed to say I didn't check the fuses properly. I checked continuity on the contacts on the back of the fuse without pulling them out thinking if it was blown it would read open. I didn't assume that both sides of some fuses would be going to ground so that it would still read continuous even if the fuse was blown. So, it was the fuse.
However it's interesting that the computer was not kidding about the LDCM no comm message. The DS wouldn't control the PS stuff. But then I switched the PS module to the DS and it controls everything now on both sides. But with the DS module in the PS, now the PS won't control the DS lock. So the serial part of the board in the LDCM doesn't work, or the contact is bad.
However it's interesting that the computer was not kidding about the LDCM no comm message. The DS wouldn't control the PS stuff. But then I switched the PS module to the DS and it controls everything now on both sides. But with the DS module in the PS, now the PS won't control the DS lock. So the serial part of the board in the LDCM doesn't work, or the contact is bad.
05-27-2011, 12:22 AM
#5
Glad to hear it was just a fuse. If it was a ground problem at G202 I think you'd have a lot of other issues. The fact that you blew the fuse tells me there was a short-to-ground somewhere, so you might want to double-check the leads going into the connectors in the accordian.
Regarding the DCM swap, did you happen to disconnect the battery? Power-cycling all the computers on the bus will cause them to rebroadcast and relearn who everyone else is. Perhaps the swap left-to-right confused the BCM as the learnt address moved.
It's possible the Transmit on the OBD interface chip failed, but Receive is clearly working. From the SI description, the left DCM sends messages to the right one over the serial bus to command it to open and close the window and locks. If that works from your DS DCM, the other has to be listening. You can confirm this functionality with unlock from your key fob which should unlock both doors.
Hopefully disconnecting the battery for a couple minutes will clear it up. It's worth a try. If you then review the DIC codes (a list of all the computers present on the bus), if your missing LDCM still reports as "no comm" its broadcasts are not heard. If it is listed and says "no codes", it is actively reporting the fact there are no codes which would be a good sign.
Todd
Regarding the DCM swap, did you happen to disconnect the battery? Power-cycling all the computers on the bus will cause them to rebroadcast and relearn who everyone else is. Perhaps the swap left-to-right confused the BCM as the learnt address moved.
It's possible the Transmit on the OBD interface chip failed, but Receive is clearly working. From the SI description, the left DCM sends messages to the right one over the serial bus to command it to open and close the window and locks. If that works from your DS DCM, the other has to be listening. You can confirm this functionality with unlock from your key fob which should unlock both doors.
Hopefully disconnecting the battery for a couple minutes will clear it up. It's worth a try. If you then review the DIC codes (a list of all the computers present on the bus), if your missing LDCM still reports as "no comm" its broadcasts are not heard. If it is listed and says "no codes", it is actively reporting the fact there are no codes which would be a good sign.
Todd
Last edited by toddk; 05-27-2011 at 12:24 AM.
