Hi all,
Tuesday the 2008 SR5 V6 didn't start. Went click, click, click. Then I see that the rear wiper is standing up straight as if it was on. I check the wiper controls and it is turned off. I play with the wiper controls and it parks the rear wiper.

I charge the battery. The Runner starts. Two days later today the same thing happens. I am sure the rear wiper was not turned on but when I get in the car and try to start it I see the rear wiper is stuck straight up and the car won't start.

I pull the 15 Amp "RR WSH" fuse hoping that this will disable the rear wiper until I can figure this out. No luck. Now when I drive the wiper keeps running and I can not turn it off. Plus, the rear window won't go down. So I put the 15 Amp RR WSH fuse back in. Rear Window works, rear wiper works. I am baffled.

I read some posts here about the tailgate wiring cracking over time and pull the rubber boot off to check the wires. Wires are good. No cracks.

What could cause the rear wiper to come on after I park the car and lock it? Shouldn't everything be powered off?

Thanks for your suggestions!

Have your battery tested and replaced if it's bad, one symptom of a battery going bad or is close to being discharged is the rear wiper will come on by itself, usually it will only do one wipe when you turn the ignition on, and it might have done that and then the battery would not start the vehicle.

It's also possible the battery isn't bad but the alternator is bad and not charging the battery properly so have it tested as well, it's also possible that both the alternator and the battery are bad but are just on their last leg and need replacing.

Sometimes a bad battery can damage the alternator and vise versa, a bad alternator damaging the battery.

Oh, wow. How odd. Weak battery makes rear wiper come on? On Monday I got a jump from my friendly Farmers Agent who was in the neighborhood. I let it run for a while. Turned it off and it came back on. It did charge the battery as later that day I was able to go 10 miles to shop Winco and back w/o trouble. So that means alternator is good? How would one tell if a battery is bad and does not hold a charge? I am charging it right now with a charger.

Yes it's odd about the wiper but it does that on these 4th Gen T4Rs.

Check some of the local auto parts stores in your area, most if not all will test both the battery and alternator for free, they have a special tester for testing both.

HA! I just went to try and start it and it is as you say. I turn on the ignition and wait for all the dash lights to go off and I hear this noise that gets quieter and quieter until it dies (what's that anyway?). When I turn the key to start the car the rear wiper does come on once and then parks all while I hear the click, click click of the starter failing....
I guess I'll get a jump and drive to O-Reilly's for a new battery...

If the charging system is fine, pop the interior panel off the rear hatch and disconnect the plug to the wiper.

Update and hopefully lasting solution:
Went to O'Reilly where they found the alternator to be fine and the just over 5 year old Interstate All Season Battery to be bad. Swapped it out right there. Two days later car starts all normal. Thank you AuSeeker for sharing your insight and guiding my decision-making process!!

You can thank this forum because without it I wouldn't have the information to solve your issue to share with you, this is a great resource and forum!

Just pay it forward if you ever can help someone else solve their issue!