<!-- from fixya rte -->How does folding mirror work - 2001 GMC Yukon Denali

ebay parts or worse amazon.
?
or wrong parts ordered.

The mirror fold feature on the Navigator is known to be a flaky design. If someone manually folds a mirror then the entire systems gets confused and will not work. There is a procedure in the service manual to synchronize the mirrors but I have never been able to get it to work.
Further adding to the problem is that the assembly is not serviceable. You have to replace the mirror and many sellers will not guarantee the fold feature to work.

Outside Mirror May Fold Out to Far : BMW 328i Common ...

repairpal.com > Problems > BMW > 328iside mirror fold out too far . and how to reset to normal . thanks. Upvoted .... side view mirror keeps folding out in a very extended position when I hit unlock.

I think that the drive screw that moves the mirrors has stripped and you will need a new unit.

Does the other side mirror work?

If the other side mirror adjusts with the switch, then it could be an issue with the mirror which isn't working.
Usually a mirror has two motors, one for up/down and another for left/right. If the mirror works in one direction and not in the other, yet the mirror on the other side works in all directions, then the issue is not the switch, but the mirror.

Unless none of that is relevant and you are talking about the fold function.

If neither mirror folds when you depress the fold button, then you need to check or change the switch as the most likely cause of the issue.
If you can provide me with a picture of the switch, then I can try to advise on how to remove and replace it.

{: ) Have someone control the power fold buttons, while you check closely the passenger mirror. If you can feel or hear even a faint hum of the motor while commanded, try giving it a little help, but don't force it if you think it doesn't have enough power to extend or retract itself. The motor could be really stuck or inoperative.
Sometimes when the mirror has been accidentally or manually folded, it needs to be reset by just pressing on the fold buttons a few rounds and let the mirrors fold by itself. Like an exercise.
If you hear the humming noise whenever the fold buttons are pressed, we can assume that the circuit on that side is ok since it is responding electrically, and that a jammed or stuck mechanism is preventing it to move.
If you don't feel or hear any humming, as in totally no sign of response, then there will be additional considerations before deciding to go for a replacement mirror. You will need to confirm if the fault is on the wirings, a door module, or the mirror motor itself. A scan tool test may be recommended for effective diagnosis.
The power fold mirror can be serviced as an assembly. So, goodluck.

Grab the passenger mirror with both hands. Fold the mirror all the way forward, all the way back and then back to the home position. Sometimes the mirror will get off track if it has been bumped or moved out of place manually.

The power mirrors are controlled by a module (computer) DDM - drivers door module an the PDM - passenger door module .
Folding Mirror System
Folding Mirror System Controls
The folding mirror system requires signals from 2 separate switches. The mirror select switch must be in the neutral/fold position and the mirror direction switch must be activated to the left/extend or right/retract positions. Both switches are integrated into the DDM and provide direct signals.
Folding Mirror System Operation
Upon receipt of the required switch inputs the DDM will supply battery voltage and ground to the mirror fold motor control circuits to perform the requested extend or retract function. The DDM will also send a class 2 message to the PDM indicating the requested function. The PDM will supply battery voltage and ground to the mirror fold motor control circuits to perform the requested extend or retract function.

Power Mirror System
Power Mirror System Components
The power mirror system consists of the following components:
• The driver door module--Class 2 module with integrated switches and requires programming when replaced
• The passenger door module--Class 2 module with integrated switches, requires programming when replaced and also contains the RFA receiver
• The power mirror direction switch--Integrated into DDM and is a 4-position momentary switch that provides a signal input to the DDM for up, down, left/extend and right/retract with a mirror switch activation
• The mirror select switch--Integrated into DDM and is a 3-position switch that allows the operator to select the left or right mirror and also a neutral/fold position
• The left outside power mirror--Contains both the vertical and horizontal mirror motors and is serviced as a complete mirror assembly
• The right outside power mirror--Contains both the vertical and horizontal mirror motors and is serviced as a complete mirror assembly
• The body control module--Class 2 module that requires programming when replaced, serves as the power mode master and is the main message handler
• The DDM 10A fuse--Located in the I/P fuse block and is hot at all times
• The PDM 10A fuse--Located in the I/P fuse block and is hot at all times
• The memory switch, if equipped with memory mirrors--Supplied power by the DDM and provides a voltage signal to the DDM upon a switch activation
• The horizontal and vertical position sensors, if equipped with memory mirrors--Supplied a 5-volt and low reference by the DDM/PDM and provide a variable voltage signal to the DDM/PDM that is proportional to mirror position
• The park neutral position switch, if equipped with memory mirrors--Provides transmission gear selection information to the PCM and is used for memory recall and mirror tilt in reverse functions
• The powertrain control module, if equipped with memory mirrors--Class 2 module that requires programming when replaced and provides Class 2 message indicating transmission gear selection
• The driver information center (DIC), if equipped with memory mirrors--Part of the instrument cluster which is a Class 2 module that requires programming when replaced and is used to personalize the memory recall and mirror tilt in reverse functions
• Fold motor in each of the outside mirrors, if equipped with power fold mirrors--Provides extend and retract movements of the mirror and is serviced as a complete mirror assembly
Each of the outside power mirrors contains 2 reversible motors to provide horizontal and vertical movement of the mirror glass. The vertical motor operates the up and down directions and the horizontal motor operates the left and right directions. If equipped with power folding mirrors, each outside power mirror will contain a reversible fold motor to operate the extend and retract functions. Each of the mirror motors are circuit breaker protected.
DTC B1722
The driver door module (DDM) and passenger door module (PDM) switch the mirror fold motor control circuits to battery voltage and ground in response to mirror extend or retract command.

The power folding function of your exterior mirrors on your '04 H2 depends on a plastic gear to collapse those mirrors at the touch of a button. That plastic gear strips very easily. The service adviser at our Hummer dealership said that problem was rectified in later model years with a redesign of of the collapsing mechanism of those mirrors.

I don't mind manually folding our mirrors, and I was afraid to ask about the cost of the parts required to solve the issue. The service guy didn't volunteer the cost of the fix. Not typically covered by aftermarket extended service/warranty plans.

the fuse for the mirrors is in the fuse block inside the car on the left side of the dash-however the mirrors do not fold in with the switch,you fold them in with your hand-usually for storage(car cover)