NEED HELP Need Help - Troubleshooting Passenger Door Module

[TequilaWarrior]

I've had intermittent issues in the past with my passenger door - windows not working, seat heater not working, door not reporting "open" to the DIC.... but now it seems these issues appear more frequently. If I "reset" the door by either unplugging the door's pigtail in the door jamb, or by pulling the right fuses, everything works fine for a short period of time. In warm weather it may last weeks, but in this bitter cold it seems it lasts one drive cycle. I'm not sure what troubleshooting steps to take from here...

My gut says the passenger door module is flaky/bad, but there's always the possibility it's a wiring issue.

This past fall I pulled the PDM and cleaned it well with electronics cleaner, cleaned all the connectors from the PDM and in the door jamb, then greased the pigtail in the door. It worked great for a while, but now it's back to needing reset every drive cycle.

Is it time to replace the PDM? Does anyone have a good source for "not expensive" PDM's?

 

[TJBaker57]

When the issues happen,, is it all of these things don't work all at once? Or do some functions work and some don't??

 

[mrrsm]

You are not alone in trying to figure out "How To Diagnose Issues with Door Locks, Actuators and Lift-Gates" considering the myriad number of Electrical and Electronic Devices that are involved here. BUT... Snap-On saw fit to include the feature called "Guided Component Testing" into its OEM Snap-On Vantage Pro Graphing Multi-Meter that is THE BOMB!

It works like -->THIS:

I entered YOUR Vehicle specifically into the Tool by Year, Make and Model and Queried the Internal Systems to show the following information that I took discreet images of...One After The Other in their sequence for determining the following things:

(1) What is the Year, Make and Model of the SUV?

(2) Using the Guided Component Test Feature, "HOW do the Door Locks Function" (Theory of Operation)?

(3) WHERE are the Door Locks & Lift Gate Mechanisms and their Harnesses tucked away inside of the Vehicle?

(4) WHAT do the various Door Locks and Actuators & Plastic Electrical Harness Connections LOOK Like (PROBE-PIN-OUTS?) ?

(5) HOW Do I attach my DMM or Oscilloscope Back-Probe Leads into these Components' PIN-OUT Locations?

(6) WHAT Kind of TESTS do I Perform and WHAT are the Nominal Power Measurements in Voltage and Ohms for Resistance involved to determine whether things are working...or NOT?

The Following 86 Images had to be broken up into Many Groups of 20 and posted consecutively and THESE contain ALL of the Answers to ALL of the Above Questions. By using a Basic DMM and a Test Light, those Tools should go a very long way in helping You to make a Proper Diagnosis. Of course...Having a decent Bi-Directional Scan Tool that allows for the Actuation of the Door Locks to All Four Doors and the Lift Gate Rear Glass Lock and Wiper is BEST...But Key Fobs will DO for most Actuation Tests:

Here we go...




More To Follow...

 

[mrrsm]

First Batch of 18 Images:



More To Follow...

 

[mrrsm]

Second Batch of 20 Images:



More To Follow...

 

[mrrsm]

Third Batch of 20 Images:



More To Follow...

 

[mrrsm]

Fourth Batch of 20 Images:



More To Follow...

 

[mrrsm]

Final Batch of 6 Images:



That is about as comprehensive as I can get with offering You an Identical Mechanic's View of How this would be investigated, either at the Dealership or at a Pro Shop. Hope This Helps Pin-Point the Issue(s) and Leads to a Verifiable Repair.

 

[TequilaWarrior]

When the issues happen,, is it all of these things don't work all at once? Or do some functions work and some don't??

When the issue happens, it's like the passenger door isn't plugged in. Passenger lock doesn't work, passenger window doesn't work, passenger heater doesn't work, passenger mirror doesn't work. Also, the DIC doesn't show when the passenger door is opened and the courtesy lamps do not illuminate when the passenger door is open.

Forgot to mention: occasionally when the issue happens, I'll hear the doors repeatedly trying to lock.

 

[mrrsm]

It would be worth eye-balling a good Wiring Diagram so as to isolate down to just the door...and after pulling the Passenger Door Panel, examine where the Interior Electrical Harness-Grommet feeds in at the Door Hinges for Broken or Shorted Wires...and check the Fusing that services all of the Passenger side Door components.

 

[TJBaker57]

When the issue happens, it's like the passenger door isn't plugged in. Passenger lock doesn't work, passenger window doesn't work, passenger heater doesn't work, passenger mirror doesn't work. Also, the DIC doesn't show when the passenger door is opened and the courtesy lamps do not illuminate when the passenger door is open.

Forgot to mention: occasionally when the issue happens, I'll hear the doors repeatedly trying to lock.

So to me this would suggest either a loss of power/ground to the FPDM OR a loss of communications from the FPDM.

The nighttime backlighting of the window switch on the right rear door uses the same ground, G303, as the FPDM. That might show whether the ground G303 is OK or not when the issue is present. I would be surprised if that ground is bad as it is located in a fairly well protected area, the lower right B pillar.

Also verify the fuse for the FPDM is OK and snug in its socket.

Perhaps also check the conditions at the door harness connection of course.

I have a set of front door modules in my stash. I think they have the seat heater switches. I'll try to remember to check that when I am out in the shop today.

 

[Mooseman]

You could swap the door modules side to side and see if the problem follows. If it stays in the same door, I would suspect the wiring.

Probably the best place to find replacements would be a Pick-n-Pull yard or eBay. Now you have a Bravada. Rare enough bird but you could try swapping in one from a TB or Envoy. The switch assembly/module is held in with clips and should allow you to swap into the Bravada's plastic escutcheon.

 

[TJBaker57]

@TequilaWarrior

Any update??

 

[TequilaWarrior]

@TequilaWarrior

Any update??

Nothing useful.... weather has been bad and I've had to put my Bravada on a charger every time I park it. The last time I took it out anywhere the passenger side mirror kept trying to go up/right the whole time, even after I turned the car off. Now, if I unplug the door altogether I get a "service airbag" warning and light... so leaving the door unplugged altogether isn't really an option. When I feel a little better(have COVID at the moment) and the weather doesn't suck, I'll try swapping the modules left/right but I'm skeptical that'll be possible as their are considerably more switches on the driver's door than the passenger door.... but admittedly, I haven't had both off at the same time to compare them and don't remember what the passenger module looked like when I did have it off to clean it.

 

[TJBaker57]

Now, if I unplug the door altogether I get a "service airbag" warning and light... so leaving the door unplugged altogether isn't really an option

Pull the #12 fuse in the rear fuseblock maybe? That is the fuse for the passenger side front door module. That won't affect the Airbag system but it would stop the mirror. Also kills the window and the lock/unlock action as well as the seat heater. The Airbag code you're seeing is likely for the side impact sensor in the front passenger door being disconnected.

The last time I took it out anywhere the passenger side mirror kept trying to go up/right the whole time, even after I turned the car off.

Unless the switch on the drivers side is going bad this sounds like evidence the FPDM is getting flaky. There are no wires controlling the passenger side mirror from the drivers side door mirror switch. It is done by messaging on the data bus. So the only way that mirror could be moving is by the drivers side mirror switch telling the FPDM to move the mirror or that FPDM has a problem.

Was that passenger door left open in rain or the window left open such that water got to the module??

FWIW I looked in my stash and found a 2002-2005 FPDM with seat heater switches. I would expect it would fit all GMT360/370 regardless of badging. I powered it up a had a chat with it so I know at the least it is alive. Also checked that it reports the action of a door ajar switch properly. Haven't tested anything further on it.

 

[TequilaWarrior]

Pull the #12 fuse in the rear fuseblock maybe? That is the fuse for the passenger side front door module. That won't affect the Airbag system but it would stop the mirror. Also kills the window and the lock/unlock action as well as the seat heater. The Airbag code you're seeing is likely for the side impact sensor in the front passenger door being disconnected.



Unless the switch on the drivers side is going bad this sounds like evidence the FPDM is getting flaky. There are no wires controlling the passenger side mirror from the drivers side door mirror switch. It is done by messaging on the data bus. So the only way that mirror could be moving is by the drivers side mirror switch telling the FPDM to move the mirror or that FPDM has a problem.

Was that passenger door left open in rain or the window left open such that water got to the module??

FWIW I looked in my stash and found a 2002-2005 FPDM with seat heater switches. I would expect it would fit all GMT360/370 regardless of badging. I powered it up a had a chat with it so I know at the least it is alive. Also checked that it reports the action of a door ajar switch properly. Haven't tested anything further on it.

To my knowledge my doors/windows were never left open significantly. I pulled the FPDM module apart this past summer and cleaned it out with electronics cleaner suspecting contamination of some sort. I have kids so the possibility that something got spilled in the switch was high on the list. The switch looked great inside and out. I'll pull the fuse until I can get the module replaced.

Do you know what you might ask for that module? I would be interested depending on the price.

 

[TJBaker57]

Do you know what you might ask for that module? I would be interested depending on the price.

I grab these things just for my hobby of fiddling with the network side to see what I can learn from them. Other than that I don't need them.

You can have it for the cost of shipping.

We should verify the fit for your vehicle. The number I have is 15204683. Fairly sure that it has been superceded by later numbers.

I may be able to further verify other functions like the window switch and maybe the seat heater switches as well.

Would be nice to fully diagnose your particular trouble before just swapping out the module.