Strange electrical problem when wipers used

[TheLexusFlexes]

Hi all. 2006 Escalade w/ about 75k on the clock. I just noticed that with the windshield wipers set to intermittent, the power to the rear-view mirror seems to go out. Specifically I'm referring to the green LED light on the lower left portion, and the LCD compass display in the upper right corner. Whenever I have the wipers on intermittent, using the first 4 or 5 speed settings, the wipers move up to their maximum excursion, and then as soon as they start to move down, the mirror seems to lose power. Like I said, the problem is characterized by the green LED light (left side) going out, and the compass LCD goes out for a second too. When it comes back on a second later, all of the compass LCD segments illuminate for a couple of seconds, just like when you first start up the car. The problem doesn't seem to happen when the wipers are running constantly and not intermittent.

Any idea what could be causing this? Is it indicative of a problem with something deeper than the mirror?

 

[Gshep]

Could the wiper motor be going bad thus drawing excessive power causing these other problems. If it only happens when you use te windshield wipers that is were I would start. use the rear wipers and see if anything happens if not that is good.... If only when you use the front wipers then I be getting that fixed asap before you get some overheaded wires. my opinin.... Let me know what happens...

 

[TheLexusFlexes]

Could the wiper motor be going bad thus drawing excessive power causing these other problems. If it only happens when you use te windshield wipers that is were I would start. use the rear wipers and see if anything happens if not that is good.... If only when you use the front wipers then I be getting that fixed asap before you get some overheaded wires. my opinin.... Let me know what happens...

I would think if the wiper motor were drawing excessive power, it would blow the fuse. Further to your point about over-current out of the motor, remember that this behavior only happened with the wipers on intermittent, not on every duration setting. Motors, because they're simple resistive-inductive devices, should (theoretically) exhibit the same properties in terms of current draw all the time.

I was thinking something along the lines of EMI, harmonics from the motor or from a variable drive, etc. interfering with logic that powers the rear-view mirror. I had hoped it was a known issue (since these GMT800s seem to have lots of minor electrical bugs). Whatever the case, it only happened once, and I haven't observed it ever since. If I find any useful information, i'll update the thread and pass it along.

Thanks!