Power Fold Mirrors - How To Repair Video
#1
03-08-2017, 09:14 AM
#2
03-08-2017, 02:36 PM
Great insight to a mysterious functioning device that can drive Hummer H2 owners mad.
On that mirror controller board check the pins soldered to the back side of the controller board for cracks in the solder. Make sure the mechanical mirror in and out switch itself works properly.
Now for the IC on the controller board, if you know the pin out for the in and out pin you can test the IC with a logic probe for high and low signal. You can also do this with a volt meter set at 5 volts dc. I have to type this in caps cause it is not to be ignored. NEVER TOUCH ANOTHER PIN AND SHORT THE PIN YOU ARE TESTING WITH THE PIN NEXT TO IT.
You will need someone to actuate the button switch with the entire circuit connected as you watch the voltage at both pins when the mirror switch is used both ways.
This will save you from shot gunning the controller IC. If the IC is found to be bad, simply cut the pins with a dremel tool top side as close to the IC body so you can solder the new IC from the top of the board to the pins standing up off the board.
Good luck and thanks for the mirror motor vid.
On that mirror controller board check the pins soldered to the back side of the controller board for cracks in the solder. Make sure the mechanical mirror in and out switch itself works properly.
Now for the IC on the controller board, if you know the pin out for the in and out pin you can test the IC with a logic probe for high and low signal. You can also do this with a volt meter set at 5 volts dc. I have to type this in caps cause it is not to be ignored. NEVER TOUCH ANOTHER PIN AND SHORT THE PIN YOU ARE TESTING WITH THE PIN NEXT TO IT.
You will need someone to actuate the button switch with the entire circuit connected as you watch the voltage at both pins when the mirror switch is used both ways.
This will save you from shot gunning the controller IC. If the IC is found to be bad, simply cut the pins with a dremel tool top side as close to the IC body so you can solder the new IC from the top of the board to the pins standing up off the board.
Good luck and thanks for the mirror motor vid.
#3
03-09-2017, 05:08 AM
[On that mirror controller board check the pins soldered to the back side of the controller board for cracks in the solder. Make sure the mechanical mirror in and out switch itself works properly.]
The full-bridge driver chip controls the drive direction using Out1 (Pin9) and Out2(p12) set to the required voltages, as this works in one direction the tracks and pins must be OK, it also means that the problem must be either a faulty chip or its not being instructed to move.
The chip uses an SPI busto receive commands digitally from the Hummer's main BCM, its possible that the "retract" command is not being sent and with a bit more time I could prove this using a serial analyser to decode the command strings but its alot of effort.
[You will need someone to actuate the button switch with the entire circuit connected as you watch the voltage at both pins when the mirror switch is used both ways.]
At the end of the video you can see I hooked up two 12V LED clusters to the drive-pins (Brown & Gray wires), one strip activates with Brown = +12V Gray = GND, and the other strip activates with Gray = +12V and Brown = GND, again as you can see only one strip activates which exactly replicates what the mirror motor does.
[This will save you from shot gunning the controller IC. If the IC is found to be bad, simply cut the pins with a dremel tool top side as close to the IC body so you can solder the new IC from the top of the board to the pins standing up off the board.]
Actually this may not be possible, the underside of the chip is a heatsink and is soldered directly to the PCB, hard to remove without the right tools. Fortunately
I have suface-mount PCB rework facilities here so I can heat the chip off and if it isnt faulty put it back on again, you wont be able to visibly tell its been changed.
When my chip arrives I'll fit it and post the results, if it still doesnt work I'll go down the serial analyser route, it could be the BCM needs resetting/reprogramming somehow.
I design electronics for a living so the controller is the easy bit for me, engines though are another matter
The full-bridge driver chip controls the drive direction using Out1 (Pin9) and Out2(p12) set to the required voltages, as this works in one direction the tracks and pins must be OK, it also means that the problem must be either a faulty chip or its not being instructed to move.
The chip uses an SPI busto receive commands digitally from the Hummer's main BCM, its possible that the "retract" command is not being sent and with a bit more time I could prove this using a serial analyser to decode the command strings but its alot of effort.
[You will need someone to actuate the button switch with the entire circuit connected as you watch the voltage at both pins when the mirror switch is used both ways.]
At the end of the video you can see I hooked up two 12V LED clusters to the drive-pins (Brown & Gray wires), one strip activates with Brown = +12V Gray = GND, and the other strip activates with Gray = +12V and Brown = GND, again as you can see only one strip activates which exactly replicates what the mirror motor does.
[This will save you from shot gunning the controller IC. If the IC is found to be bad, simply cut the pins with a dremel tool top side as close to the IC body so you can solder the new IC from the top of the board to the pins standing up off the board.]
Actually this may not be possible, the underside of the chip is a heatsink and is soldered directly to the PCB, hard to remove without the right tools. Fortunately
I have suface-mount PCB rework facilities here so I can heat the chip off and if it isnt faulty put it back on again, you wont be able to visibly tell its been changed.
When my chip arrives I'll fit it and post the results, if it still doesnt work I'll go down the serial analyser route, it could be the BCM needs resetting/reprogramming somehow.
I design electronics for a living so the controller is the easy bit for me, engines though are another matter
Last edited by oceanbrave; 03-09-2017 at 08:23 AM.
#5
03-09-2017, 08:13 AM
I'd be very interested if you delve into the BCM. I've not pulled mine out but I eventually plan on getting a second one to experiment with some. I want to add features that either were never offered or offered on a later year or modify a function. A couple of examples that I am specifically wanting to do...
Anyways - sorry to ramble off topic some on this but what you are looking at is more on the level of things I'm also looking at.
The front DRL lights. Ok in some places like Canada they are required by law and of course some people just want them regardless. I feel that huge 4.5 inch lights in the bumper are a bit much for DRL's and most people who are not aware think those are driving/fog lights anyways. Anyways I want to change those to driving/fog lights and I want to use a factory GM switch. Specifically the switch from the full size GM SUV's with a rear wiper as shown below.
This switch is an exact fit and can replace our rear wiper switch. The rear wipers will work perfectly fine. The fog light button will however need a bit to make it do anything. If you get one of these switches you will also want to get a cut off plug or the correct additional pins for the wiring connector. The button is a momentary low current type. Its intended to control (through logic or directly) a latching relay. Now I could just wire in a latching relay myself, cut the wires to the DRL's and tie those into the new relay (as well as adding a power circuit and fuse for the relay) and get them going and sitting in the drivers seat it would look 100% factory.
However - the GM truck BCM's for pretty much 2003 - 2007 are pretty much all the exact same. They just have different programming. My H2 even has a fog light fuse in the underhood fuse box (because its also the exact same fuse box in other GM trucks for the GMT800 platform). However everything I can find says the GMT800 BCM's are only one time programmable. Even the GM documents state this. If you get a new unprogrammed BCM, using a Tech2 and the TIS software you program the VIN and then tell it the vehicles RPO codes (options the vehicle has) and then it will program the new BCM. The Tech2 and the TIS system will NOT do this on a used BCM. So it sounds like the GMT800 platform BCM's have a PROM, not an eeprom. I'm skeptical though. The same Tech2 and TIS system can reprogram used PCM's just fine, just not BCM's. So my line of thinking is okay, I need to figure out what the prom or eeprom chip is on a BCM and if its indeed a one time write prom, then find an equvalent packaged eeprom and replace the chip. Viola' - reprogrammable BCM. That or get a test clip for the specific prom/eeprom (or god forbid its an old UV erasable one then just remove the sticker and erase it) and see if I can figure a way to erase it to be like a new unprogrammed one.
Anyways - I've run into this before adding fog lights to a GM pickup that did not have them from the factory. The factory wiring was there, so added the lights and factory switch and nothing. Ended up having to buy a new BCM, then add the RPO option when setting up the BCM programming. Then plugged the new BCM in and they immediately worked. So the thing is, the BCM we have is already fully capable of these things, we can add this fog light switch (and some wiring work since the H2 was never configured for factory fog lights) and then we just need to change the BCM programming.
Another example is the drivers door heated seat switch. On some GM trucks like my H2 its pretty plain. There are other GM trucks like the Escalade which have power adjustable pedals. And others like some later H2 models (I think 2006, 2007) that have a "Global Windows" function which are two buttons that can raise or lower ALL windows at the same time. I'd like to add this global windows feature to my 2003. The only thing that prevents me from this is having the right switch module and the right programming in my BCM. The below shows the three variations of the switch module. They are all the exact same size and have the exact same connector. I currently have the top version and want to change mine to the middle one. I'm not really wanting to try and add power adjustable pedals...
Anyways - sorry to ramble off topic some on this but what you are looking at is more on the level of things I'm also looking at.
The front DRL lights. Ok in some places like Canada they are required by law and of course some people just want them regardless. I feel that huge 4.5 inch lights in the bumper are a bit much for DRL's and most people who are not aware think those are driving/fog lights anyways. Anyways I want to change those to driving/fog lights and I want to use a factory GM switch. Specifically the switch from the full size GM SUV's with a rear wiper as shown below.
This switch is an exact fit and can replace our rear wiper switch. The rear wipers will work perfectly fine. The fog light button will however need a bit to make it do anything. If you get one of these switches you will also want to get a cut off plug or the correct additional pins for the wiring connector. The button is a momentary low current type. Its intended to control (through logic or directly) a latching relay. Now I could just wire in a latching relay myself, cut the wires to the DRL's and tie those into the new relay (as well as adding a power circuit and fuse for the relay) and get them going and sitting in the drivers seat it would look 100% factory.
However - the GM truck BCM's for pretty much 2003 - 2007 are pretty much all the exact same. They just have different programming. My H2 even has a fog light fuse in the underhood fuse box (because its also the exact same fuse box in other GM trucks for the GMT800 platform). However everything I can find says the GMT800 BCM's are only one time programmable. Even the GM documents state this. If you get a new unprogrammed BCM, using a Tech2 and the TIS software you program the VIN and then tell it the vehicles RPO codes (options the vehicle has) and then it will program the new BCM. The Tech2 and the TIS system will NOT do this on a used BCM. So it sounds like the GMT800 platform BCM's have a PROM, not an eeprom. I'm skeptical though. The same Tech2 and TIS system can reprogram used PCM's just fine, just not BCM's. So my line of thinking is okay, I need to figure out what the prom or eeprom chip is on a BCM and if its indeed a one time write prom, then find an equvalent packaged eeprom and replace the chip. Viola' - reprogrammable BCM. That or get a test clip for the specific prom/eeprom (or god forbid its an old UV erasable one then just remove the sticker and erase it) and see if I can figure a way to erase it to be like a new unprogrammed one.
Anyways - I've run into this before adding fog lights to a GM pickup that did not have them from the factory. The factory wiring was there, so added the lights and factory switch and nothing. Ended up having to buy a new BCM, then add the RPO option when setting up the BCM programming. Then plugged the new BCM in and they immediately worked. So the thing is, the BCM we have is already fully capable of these things, we can add this fog light switch (and some wiring work since the H2 was never configured for factory fog lights) and then we just need to change the BCM programming.
Another example is the drivers door heated seat switch. On some GM trucks like my H2 its pretty plain. There are other GM trucks like the Escalade which have power adjustable pedals. And others like some later H2 models (I think 2006, 2007) that have a "Global Windows" function which are two buttons that can raise or lower ALL windows at the same time. I'd like to add this global windows feature to my 2003. The only thing that prevents me from this is having the right switch module and the right programming in my BCM. The below shows the three variations of the switch module. They are all the exact same size and have the exact same connector. I currently have the top version and want to change mine to the middle one. I'm not really wanting to try and add power adjustable pedals...
#6
03-14-2017, 04:35 PM
Power Fold Mirrors - Won't Retract
Well finally got the new IC's STL9949 (now have spares too!) and replaced the IC (see jpgs)
However the problem remains and makes no sense, its as if the BCM (or whatever) is just not sending the retract command.
Now the Manual says:-
"Power Folding Mirrors
To fold or unfold the mirrors, move the selector switch, located above the mirror control, to the middle glass cleaner. The mirror control will illuminate. Press the right or left side of the mirror control to fold or unfold the the mirror. The mirror will adjust as it folds in and will reposition itself once it is unfolded."
As my power folds have never worked I am unfamiliar with their operation, so perhaps there's something I'm not doing correctly. Pressing "Right" works, pressing "Left" doesn't i.e. there's no drive voltage accross the mirror motor. It can't be the door control module comms because it unfolds OK. It isn't likely to be the chip as its been changed and the same wiring, tracks and pins are used for both operations, the part the chip plays is to reverse the polarity.
So it looks like either the BCM or the 4-way switch pad on the drivers door. One final clue, I swear at the begining I saw the arm retract for a second, could it be the BCM detected a fault and has now inhibited this function? Is this even possible?
Feel a Tech2 coming ON.
Any thoughts much appreciated..
However the problem remains and makes no sense, its as if the BCM (or whatever) is just not sending the retract command.
Now the Manual says:-
"Power Folding Mirrors
To fold or unfold the mirrors, move the selector switch, located above the mirror control, to the middle glass cleaner. The mirror control will illuminate. Press the right or left side of the mirror control to fold or unfold the the mirror. The mirror will adjust as it folds in and will reposition itself once it is unfolded."
As my power folds have never worked I am unfamiliar with their operation, so perhaps there's something I'm not doing correctly. Pressing "Right" works, pressing "Left" doesn't i.e. there's no drive voltage accross the mirror motor. It can't be the door control module comms because it unfolds OK. It isn't likely to be the chip as its been changed and the same wiring, tracks and pins are used for both operations, the part the chip plays is to reverse the polarity.
So it looks like either the BCM or the 4-way switch pad on the drivers door. One final clue, I swear at the begining I saw the arm retract for a second, could it be the BCM detected a fault and has now inhibited this function? Is this even possible?
Feel a Tech2 coming ON.
Any thoughts much appreciated..
#7
03-14-2017, 04:59 PM
Again
Visually check solder joints on back of controller board where pins come up off the board. A broken solder joint could cause the problem.
Check the wiring from the control board socket plug back to the door switch that controls the mirror in and out. You can get a light emitting continuity checker to see if the button switches close and pass current when pressed at the mirror control door button.
First determine the switches function properly before shot gunning electronic circuits
Visually check solder joints on back of controller board where pins come up off the board. A broken solder joint could cause the problem.
Check the wiring from the control board socket plug back to the door switch that controls the mirror in and out. You can get a light emitting continuity checker to see if the button switches close and pass current when pressed at the mirror control door button.
First determine the switches function properly before shot gunning electronic circuits
#8
03-14-2017, 05:12 PM
Nice job on the chip swap! Better than I usually seem to manage with my hot air iron even with the right nozzle.
I'll take a peek and see what all the Tech2 shows regarding the mirrors on my 2003. Mine do not really work right either. Just been waiting to pull my door panels until I know I'll have time and also to take care of replacing the door check straps while I have it open as well as repainting the plastic surround part around the grab handle and recovering the grab itself with new leather. With the age of my truck I'm trying to minimize how often I have to remove the plastics to minimize risks of cracking anything that has gotten brittle.
I'll take a peek and see what all the Tech2 shows regarding the mirrors on my 2003. Mine do not really work right either. Just been waiting to pull my door panels until I know I'll have time and also to take care of replacing the door check straps while I have it open as well as repainting the plastic surround part around the grab handle and recovering the grab itself with new leather. With the age of my truck I'm trying to minimize how often I have to remove the plastics to minimize risks of cracking anything that has gotten brittle.
#9
03-15-2017, 05:57 AM
Again
Visually check solder joints on back of controller board where pins come up off the board. A broken solder joint could cause the problem.
Check the wiring from the control board socket plug back to the door switch that controls the mirror in and out. You can get a light emitting continuity checker to see if the button switches close and pass current when pressed at the mirror control door button.
First determine the switches function properly before shot gunning electronic circuits
Visually check solder joints on back of controller board where pins come up off the board. A broken solder joint could cause the problem.
Check the wiring from the control board socket plug back to the door switch that controls the mirror in and out. You can get a light emitting continuity checker to see if the button switches close and pass current when pressed at the mirror control door button.
First determine the switches function properly before shot gunning electronic circuits
Also the 4-way pad does work. Although my driver's side power fold doesnt work (yet to fix) I can hear the motor trying to retract but not extend, the exact opposite of the passenger side. This tells me the BCM is seeing the switch for both extend and retract. Also the mirrors work in all directions, both sides.
Maybe the problem with the driver's side its inhibiting the passenger side but it seems odd it should operate that way.
By the way the door control module is pretty sophisticated, it has a Freescale (Motorola) 8-Bit Microcontroller with 60KB of on-board flash, 1KB of security flash, 2KB of RAM, there are numerous other chips that seem to be monitoring current drain etc. Would love to get my hands on the circuit diagram.
Last edited by oceanbrave; 03-15-2017 at 06:07 AM. Reason: Footnote
#10
03-15-2017, 01:43 PM
I went out and fiddled with the Tech2 a bit some to see what it shows for the mirrors. Unfortunately I do not see any way to specifically test the folding operations. You can however actuate other operations like adjusting the mirror glass and observe the reference voltage as well as the motor status. On the status screens you can also see the power folding status and that does change when you use the button on the door to try and fold the mirrors. Two shots here. One shows the folding as idle, while the second show it trying to extend. The text on the motor for the one shot was just changing from idle to active, its not a screen defect (just the timing on my pic caught it while it was changing is all).
Interesting to me is my mirror 5V reference voltage always stays at 2V. Wonder if that has anything to do with it? To see the screen where this status is shown I had to go into one of the actual tests which in this case I picked door lock/unlock (if I hit the buttons on the Tech2 under Lock and Unlock it will lock or unlock ONLY the drivers door since I'm specifically in the drivers door module).
Also somewhat interesting is the driver door module while not giving me specific functions for the power folding mirrors does give me options for puddle lights (on some GM trucks there are lights on the bottom of the mirror housings) and power adjustable pedals (which would be adjusted using one version of the heated seat switch I showed up in post #5). Its also possible that there is a capability to specifically test the power folding mirrors if you select a different vehicle type.
However the Tech2 is not terribly intuitive on many things. One being selecting your specific vehicle on the Body Control menu - my understanding is the 3rd digit of your VIN should be the one you choose. It just gives a list of letters, A,B, C, D, etc. On my H2, the third letter of my VIN is R. I did not see Hummer mentioned in any of them and R is not one of the letters to pick from. Some letters just go right into interrogating the vehicle computers, other letters give more choices like picking Chevy, GMC, etc. On my 2003 H2 I can get into modules using a few of the letters but I have not had time to fully explore all of them, many are very obviously NOT for the Hummer like a Saturn car. My 2003 seems to match best with letter N.
Actually I just read on a couple of other sites that its the 8th letter of the VIN, then another says the 5th letter..... lol anyways the 5th letter does seem like that might be right since N works on mine.
Interesting to me is my mirror 5V reference voltage always stays at 2V. Wonder if that has anything to do with it? To see the screen where this status is shown I had to go into one of the actual tests which in this case I picked door lock/unlock (if I hit the buttons on the Tech2 under Lock and Unlock it will lock or unlock ONLY the drivers door since I'm specifically in the drivers door module).
Also somewhat interesting is the driver door module while not giving me specific functions for the power folding mirrors does give me options for puddle lights (on some GM trucks there are lights on the bottom of the mirror housings) and power adjustable pedals (which would be adjusted using one version of the heated seat switch I showed up in post #5). Its also possible that there is a capability to specifically test the power folding mirrors if you select a different vehicle type.
However the Tech2 is not terribly intuitive on many things. One being selecting your specific vehicle on the Body Control menu - my understanding is the 3rd digit of your VIN should be the one you choose. It just gives a list of letters, A,B, C, D, etc. On my H2, the third letter of my VIN is R. I did not see Hummer mentioned in any of them and R is not one of the letters to pick from. Some letters just go right into interrogating the vehicle computers, other letters give more choices like picking Chevy, GMC, etc. On my 2003 H2 I can get into modules using a few of the letters but I have not had time to fully explore all of them, many are very obviously NOT for the Hummer like a Saturn car. My 2003 seems to match best with letter N.
Actually I just read on a couple of other sites that its the 8th letter of the VIN, then another says the 5th letter..... lol anyways the 5th letter does seem like that might be right since N works on mine.
Last edited by MixManSC; 03-15-2017 at 02:19 PM.