Crazy rear wiper arm

[JBurt]

Hey everybody. I've got some electrical problem that I've finally gotten around to trying to fix. I've got a 97 SR5 and every time I start the car, the rear wiper goes through about 3 to 7 cycles and then stops in a random position. I think this happened when my daughter was playing with the switches in the cab while I was working outside and listening to the stereo in the car. The other weird thing is that if I try to use the key in the rear hatch to lower the window, it turns on the rear wiper and whenever I stop holding the key to the left the wiper immediately stops. That was about a year ago. I thought maybe it was broken wires in the loom for the rear hatch, but I couldn't find anything obvious, and I got tired of working on it so I made sure the wiper was in the home position and just unplugged the wiper (behind the window inside the rear hatch) and left it alone.

This had the unfortunate side effect of disabling my rear window as well. As I understand it the rear window won't work if the wiper is not in the "home" position. And though my wiper looks like it's down, I don't think its good enough.

Tonight I pulled apart the rear door and rechecked the wires for continuity (all good) and the grounds that are clamped together under the headliner (all good too).

I don't know if it complicates things but at one point I added a 12v outlet that is always hot for a fridge and it uses the same ground as the rear wiring loom.

I hooked up the rear wiper again and it has the same behavior. Begins random cycling every time the car is started and stops in a random position. Living in the desert I couldn't really care less about the wiper, but it would be really nice to have the window back. I don't know if I can jump some wires in the connector for the rear wiper, or if I need to replace whatever switch or sensor tells the rear ecu that the wiper is off, and my electrical skills aren't that great, but I'd appreciate any help anyone could give. Thanks.

I've replaced the blue rear control module, but that didn't help.

 

[T4R2014]

Why not just remove the wiper arm?

 

[VincentGsrq]

Have you tried leaving it switched to on or intermittent prior to starting? Then simply turn it off and let it go back to "rest" position after a cycle or two. I don't have a rear spoiler and I use my rear wiper frequently when it rains, which here in FL is often.

 

[JBurt]

T4R2014 - I could remove the wiper arm, but it still doesn't solve the problem of being able to use the window, which is the main problem. Ironic that something I don't really care about is preventing me from using one of my favorite features of my rig.

VincentGsrq - the problem is that when I switch the wiper off it doesn't stop immediately. It will continue its random number of cycles and then stop in a random place.

Something new I noticed is that if I turn the wiper on and leave it on I can hear a relay in the back click a few times at random points in the cycle. Maybe that went bad? Anyone know if there is a relay for the rear wiper and where it is?

The wiper fluid pump and nozel also work fine.

 

[Dieselchessy]

Keep in mind I’ve never messed with a Toyota wiper motor.

In other wiper motors there are greased contacts that travel back and forth With the wiper and allow the motor to change direction and stop at the end of travel once the switch is turned off.

I suspect the contacts in your motor are bad and that’s why it acts quirky.

On other vehicles you’d pull apart the motor assembly and then clean and grease the contacts or replace it.

These Toyota’s have a body ECU in the back door and maybe more stuff going on than your average Dodge or Chevy so I really couldn’t say for sure.

 

[turbodudey2]

Mine is crazy too

It doesn't activate when tuning the truck on, but if I touch the wiper switch it will cycle oddly, and stop in whatever random place it feels like.

I have to keep turning it off and on and eventually it will park in the correct place.

I wonder if it's the switch itself on the steering column that is bad...

I don't ever use the rear wiper either, so i have little motivation to mess with it.

 

[JBurt]

[MENTION=466411]Dieselchessy[/MENTION] - Thanks for the suggestion. I've poked around back there a lot and I can't find a separate position switch or anything of the like so it makes sense that it is in the wiper motor. It has 5 wires in the plug, so I imagine that it has the capacity for those functions. I was hoping that it was separate because you have to remove the rear glass to get the wiper motor out. Oh well.
[MENTION=50828]turbodudey2[/MENTION] I'm sorry your in almost the same boat, but glad I'm not alone.

I did find a small work around. Yesterday I had to take the kids to a Dr. appointment about 2 hours away. With the prospect of spending all day in the car I really wanted to get the window working to help get stuff out of the back. Anyways I just played with it enough and it miraculously got into the home position. I knew the wiper would be deactivated if the window was down, so I would roll the window up and then put it down about 1/8". That was enough to disable the wiper motor and not have any wind noise. Not sealed completely good, but for one day and one trip I was happy with it. I guess it's time to repair/replace the motor once I get time and motivation to pull the rear window out. Might be a bit because its 110 everday with about 80% humidity, but who knows. Thanks everyone and if anybody wants to still chime in let me know.