Unusual Problem - Rear Defrost/Wipers

[Bombguy]

2017 just started with an unusual problem. The rear/side defrost, rear wiper, and rear washer fluid are now all not working. Rear window up and down DOES still work.

I've checked all the fuses I can ID, and all look fine - plus, if it was a fuse I wouldn't expect all three to be out of service.

Similarly, checked the two wiring harnesses going to the tailgate visually/manipulated through the cover - no obvious damage going on.

Thoughts or suggestions?

 

[AuSeeker]

2017 just started with an unusual problem. The rear/side defrost, rear wiper, and rear washer fluid are now all not working. Rear window up and down DOES still work.

I've checked all the fuses I can ID, and all look fine - plus, if it was a fuse I wouldn't expect all three to be out of service.

Similarly, checked the two wiring harnesses going to the tailgate visually/manipulated through the cover - no obvious damage going on.

Thoughts or suggestions?

Make sure the rear window is all the way up/closed.

 

[97BlackAckCL]

Make sure the rear window is all the way up/closed.

Yes this, the wiper won't engage if the rear window is not fully closed

 

[Bombguy]

Make sure the rear window is all the way up/closed.

Nope, checked that, several times.

 

[97BlackAckCL]

Check to see if the window lock button on the driver's door is pushed, that can cause weird things with the rear hatch

 

[Bombguy]

Check to see if the window lock button on the driver's door is pushed, that can cause weird things with the rear hatch

Tried that too, no luck.

And - on the off chance maybe the switch wasn't engaging, ran the window all the way down and back up again today. Still nothing.

 

[To_fire]

Tried that too, no luck.

And - on the off chance maybe the switch wasn't engaging, ran the window all the way down and back up again today. Still nothing.

When you press the defrost button, does the indicator light turn on? Have you recently disconnected the battery? Have you tried the window reset procedure a few times in a row? I'm thinking the hatch control module is out of sync with the window position.

 

[Bombguy]

Tried that too, no luck.

And - on the off chance maybe the switch wasn't engaging, ran the window all the way down and back up again today. Still nothing.

When you press the defrost button, does the indicator light turn on? Have you recently disconnected the battery? Have you tried the window reset procedure a few times in a row? I'm thinking the hatch control module is out of sync with the window position.

The indicator light does NOT turn on - that was my first clue something was wrong. Yes, I've disconnected and reconnected the battery. I can certainly try a few more cycles of the window reset tomorrow.

Just hoping this is something simple like that and not an internal wiring problem :/

 

[Bombguy]

Tried that too, no luck.

And - on the off chance maybe the switch wasn't engaging, ran the window all the way down and back up again today. Still nothing.

When you press the defrost button, does the indicator light turn on? Have you recently disconnected the battery? Have you tried the window reset procedure a few times in a row? I'm thinking the hatch control module is out of sync with the window position.

UPDATE: Tried running it several times today, and looks like that was the issue - defrost and wipers now working. So, big thanks To_fire for that idea.

Unfortunately... now the window is sticking about an inch down... but I'll dig into that later when it's warm.

Thanks all for the help.

 

[CutthroatSlam]

UPDATE: Tried running it several times today, and looks like that was the issue - defrost and wipers now working. So, big thanks To_fire for that idea.

Unfortunately... now the window is sticking about an inch down... but I'll dig into that later when it's warm.

Thanks all for the help.

Need to inspect and probably replace the window regulator subassembly. Been there and done that. Once you have the subassembly, it’s about an hour or two to replace it.

 

[Bombguy]

Need to inspect and probably replace the window regulator subassembly. Been there and done that. Once you have the subassembly, it’s about an hour or two to replace it.

Thanks, I'll look into that next.

 

[To_fire]

UPDATE: Tried running it several times today, and looks like that was the issue - defrost and wipers now working. So, big thanks To_fire for that idea.

Unfortunately... now the window is sticking about an inch down... but I'll dig into that later when it's warm.

Thanks all for the help.

Sticking about an inch down from the top? When you perform the upper limit reset, are you pulling up and holding up the switch after it goes into the upper weatherstrip?

 

[Bombguy]

Sticking about an inch down from the top? When you perform the upper limit reset, are you pulling up and holding up the switch after it goes into the upper weatherstrip?

It's been a few days, but I believe so yes.

 

[cascade123]

It sounds like the Back Door ECU logic is inhibiting those circuits. On the 5th Gen, if the Rear Window Limit Switch doesn't report a "Closed" status, the ECU disables the wiper, washer, and defroster for safety.

Since your fuses and wiring look fine, you need to check the digital signal. you can use an Autel MK808BT Pro to diagnose this via the BCM:

Check Live Data: Pull up the PID for ‘Rear Window Position’ or ‘Limit Switch’. If it reads OPEN or ON while the glass is physically up, you've found the issue (sensor/calibration).

Active Test: Use the scanner to command the rear wiper ON. If it activates via the tool, you’ve confirmed the motor and harness are healthy, isolating the fault strictly to the window sensor.