Side Mirror Glass Removal
- Thread starter dcsang
- Start date
Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.
Not sure how similar the 2013 and 2017 models are but I have some info here:
https://www.expeditionforum.com/threads/broken-mirror-glass.39367
Basically you need to release four tabs on a circular mount centered within the glass. I used some dental tools to get in there and pull the clips. A second set of hands holding a light into there helps.
https://www.expeditionforum.com/threads/broken-mirror-glass.39367
Basically you need to release four tabs on a circular mount centered within the glass. I used some dental tools to get in there and pull the clips. A second set of hands holding a light into there helps.
marlinpruett
Full Access Members
I used a pick with a hook on the end to raise the tabs instead of a screw driver
Last edited:
dcsang
Full Access Members
I appreciate the guidance and responses. Between the weather and work hours I didn't have a chance to revisit this until today, and it was raining steadily. After removing the driver's side mirror I encountered the following.
I will have to trace the heated mirror wire to locate the failure, weather permitting. There is continuity at the connection points on the back of the mirror.
Any suggestions on reliably triggering the auto-dimming circuit and the voltage reading I should expect on the that line? The marking just below the brown connector indicates '1.4V MAX' but would like to verify considering my unfamiliarity with this circuit.
1 - detached the heated mirror connections, activated the rear defroster, and checked voltage on the GN-VT and BK wires indicated below. The reading was 3v, which is likely the cause of failure. I couldn't check the RH mirror for reference at the time but I would expect 12v since it's working correctly. I expected either 12v or 0v, so pondering causes of the low reading.
2A & 2B - The auto dimming wires were broken at the connector. This is puzzling since the connection was severed at the very end of the pins, seemingly just below the surface of the connector. It doesn't seem logical that someone would cut these wires rather than simply unplugging the connector if there was an issue with this circuit. I removed the pins from the connector, recrimped and soldered the wires, and restored the connector.
2A & 2B - The auto dimming wires were broken at the connector. This is puzzling since the connection was severed at the very end of the pins, seemingly just below the surface of the connector. It doesn't seem logical that someone would cut these wires rather than simply unplugging the connector if there was an issue with this circuit. I removed the pins from the connector, recrimped and soldered the wires, and restored the connector.
I will have to trace the heated mirror wire to locate the failure, weather permitting. There is continuity at the connection points on the back of the mirror.
Any suggestions on reliably triggering the auto-dimming circuit and the voltage reading I should expect on the that line? The marking just below the brown connector indicates '1.4V MAX' but would like to verify considering my unfamiliarity with this circuit.
dcsang
Full Access Members
Just a quick update. I tested the dimming circuit by shining variable light at the rear view mirror sensor while checking voltage on the white supply connector (exhibit 2A above). The voltage reading ranged from 0v-1.35v based on the light intensity, which falls below the 1.4v MAX indicated on the back of the mirror.
I also retested the heated mirror supply wires and got 12v (13.4v exactly but 12v will be referenced as proper voltage in this case). I manipulated the wires while testing to check for intermittent connection but voltage remained constant. I am perplexed about yesterday's 3v reading.
Snapping that glass back in place was a bit of a challenge. I positioned the lower clips first with the intention of securing the top clips last since the mirror tilts downward to provide some visibility and access but it took 3 attempts to finally get it in place. It felt secure at times but the visual inspection revealed that the top clips were not properly secured, so be diligent if you run into this.
A short test drive confirmed that the dimming is now working, but no joy with the heated mirrors. I once again removed the glass and confirmed 12v on the heated mirror circuit with the rear defroster activated. I also tested 10.5 ohms resistance between the heated mirror leads on the back of the mirror and successfully used a 12v power supply to verify functionality. The connection remains the logical culprit so I'll clean the female spade connectors with electrical contact cleaner and sand the leads next. It's still raining here and snow is expected tomorrow so timing is uncertain.
I also retested the heated mirror supply wires and got 12v (13.4v exactly but 12v will be referenced as proper voltage in this case). I manipulated the wires while testing to check for intermittent connection but voltage remained constant. I am perplexed about yesterday's 3v reading.
Snapping that glass back in place was a bit of a challenge. I positioned the lower clips first with the intention of securing the top clips last since the mirror tilts downward to provide some visibility and access but it took 3 attempts to finally get it in place. It felt secure at times but the visual inspection revealed that the top clips were not properly secured, so be diligent if you run into this.
A short test drive confirmed that the dimming is now working, but no joy with the heated mirrors. I once again removed the glass and confirmed 12v on the heated mirror circuit with the rear defroster activated. I also tested 10.5 ohms resistance between the heated mirror leads on the back of the mirror and successfully used a 12v power supply to verify functionality. The connection remains the logical culprit so I'll clean the female spade connectors with electrical contact cleaner and sand the leads next. It's still raining here and snow is expected tomorrow so timing is uncertain.
star-art
Full Access Members
I know how much work it is taking mirrors apart. Not fun!
I was thinking you might have a broken trace in the heating element, causing an open circuit. But it looks like you verified continuity so it seems your element is good. You might use an ammeter connected in series though to make sure it's drawing current.
When I had my Grand Marquis mirrors apart I noticed the heating element is just a foil layer on the back side of the glass. The connections were very tight but the metal tabs connecting the electrical plug to the foil trace weren't secured that strongly. Just unplugging the connector caused a great deal of strain and I could see the tabs trying to lift off the glass. It looked like they could be damaged quite easily.
I was thinking you might have a broken trace in the heating element, causing an open circuit. But it looks like you verified continuity so it seems your element is good. You might use an ammeter connected in series though to make sure it's drawing current.
When I had my Grand Marquis mirrors apart I noticed the heating element is just a foil layer on the back side of the glass. The connections were very tight but the metal tabs connecting the electrical plug to the foil trace weren't secured that strongly. Just unplugging the connector caused a great deal of strain and I could see the tabs trying to lift off the glass. It looked like they could be damaged quite easily.
dcsang
Full Access Members
I needed the vehicle so there was no time for extensive testing. However, this is what I observed today.
The voltage on the heated mirror supply line measured +1.5v with the defroster on and the door open. The voltage reversed to -12v when the defroster was turned off with the door open. The voltage is +12v with the door closed and the defroster on. I recall getting the initial 3v measurement with the door open but not sure why the door position affects this. The connections were cleaned but the mirror is still not heating. Perhaps checking amp draw should be the next step but I plan to remove the working passenger mirror and connect it to the driver's side for a definitive test.
Can anyone shed light of the voltage readings observed based on the door position?
Perhaps I got lucky, but the mirror snapped on in one shot this time.
The voltage on the heated mirror supply line measured +1.5v with the defroster on and the door open. The voltage reversed to -12v when the defroster was turned off with the door open. The voltage is +12v with the door closed and the defroster on. I recall getting the initial 3v measurement with the door open but not sure why the door position affects this. The connections were cleaned but the mirror is still not heating. Perhaps checking amp draw should be the next step but I plan to remove the working passenger mirror and connect it to the driver's side for a definitive test.
Can anyone shed light of the voltage readings observed based on the door position?
Perhaps I got lucky, but the mirror snapped on in one shot this time.
star-art
Full Access Members
Wow, that is weird! Sounds like you have an intermittent wire problem, perhaps a short somewhere or a loose/damaged pin.
From the FSM, Rear View Mirrors section, Pinpoint Test F, disconnect the connector (C516 left, CC622 Right) and turn the ignition ON. Turn on Rear Defog. Check voltage at Pin 8 (brown/white). If less than 10V, check BCM fuse 59 (15A). If that fuse is OK, there is a problem in the wiring between the fuse and the door mirror.
With the ignition OFF, the resistance between Pin 2 (Black/Violet) (body side of the harness) and ground should be less than 5 ohms. This verifies a proper connection to ground.
Check the "jumper harness" (I'm guessing this means the wires between C516 and the connections on the back of the mirror glass) for open circuits, loose or damaged pins. If no wiring faults can be found, replace the mirror glass.
That's about it as far as the factory manual is concerned. . .
EDIT: If there's a short, you should get a reading of a few volts or less. If you get a reading of -12V, the probes on the voltmeter are likely backwards. I can think of no way you could get a negative voltage coming out of the fuse when the other mirror is working correctly and both are being fed by the same circuit. Of course, be sure you have a good clean ground point to connect the negative probe.
It sounds to me like there's a pinch/short in the wiring that occurs when the door is opened. Or, maybe a loose or damaged pin in one of the connectors.
From the FSM, Rear View Mirrors section, Pinpoint Test F, disconnect the connector (C516 left, CC622 Right) and turn the ignition ON. Turn on Rear Defog. Check voltage at Pin 8 (brown/white). If less than 10V, check BCM fuse 59 (15A). If that fuse is OK, there is a problem in the wiring between the fuse and the door mirror.
With the ignition OFF, the resistance between Pin 2 (Black/Violet) (body side of the harness) and ground should be less than 5 ohms. This verifies a proper connection to ground.
Check the "jumper harness" (I'm guessing this means the wires between C516 and the connections on the back of the mirror glass) for open circuits, loose or damaged pins. If no wiring faults can be found, replace the mirror glass.
That's about it as far as the factory manual is concerned. . .
EDIT: If there's a short, you should get a reading of a few volts or less. If you get a reading of -12V, the probes on the voltmeter are likely backwards. I can think of no way you could get a negative voltage coming out of the fuse when the other mirror is working correctly and both are being fed by the same circuit. Of course, be sure you have a good clean ground point to connect the negative probe.
It sounds to me like there's a pinch/short in the wiring that occurs when the door is opened. Or, maybe a loose or damaged pin in one of the connectors.
Last edited:
dcsang
Full Access Members
Thank you for that info! I firmly tugged on the harness boot at the door hinge while taking the open door measurements but there was no voltage variance. That doesn't necessarily rule out a loose or bad pin as you mentioned so now I have to access the inner door panel for C516. Hopefully I get at least one decent day in the coming weekends to do this, but swapping the mirrors should be fairly quick test. I would like to check the dimming circuit on the passenger mirror anyway since I can't detect if it's working as it should. There is noticeable dimming on the repaired driver's side now when triggered.
