Karl B. Andersen

The vehicle in question is a 2000 XJ.
I had to take a 100 mile one-way trip this morning.
I stopped at a local quick-stop for a road snack and left my truck running.
And when I returned and got in the seat, I saw the rear wiper was running as well as the washer pump non-stop!
The switch was off. Flipping it off-on-off etc. was futile.
It had drained the entire washer reservoir in my absence.
All I could do was pull the fuse and continue on my trip, which I could not delay.
In about 50 miles the rear door ajar idiot light came on.
A quick stop-check verified that it was latched.
Confused.
So, I'm driving through rural northern Minnesota which is just a bunch of smaller towns.
Along the way at about 3-4 different places I stopped at the auto parts stores to see if anyone had a wiper switch on hand.
None did.
Now, what I noticed was that after getting into the vehicle after each stop, the door ajar light would take about 3-4 miles to start dimly glowing/pulsing. Off - on - dim - bright - brighter - more frequent and then full on/full bright and then would stay that way.
After each stop it would do this, like 'something' was cooling off at each stop and then after I got going and it warmed up again, the door ajar light would go through the same process.
After 8 full stops and cooling off periods over 200 miles, I had one last time to stop before heading home.
I was only in the hardware store about 5 minutes.
It's a 20 mile ride home.
The idiot light never came on.
When I got home I put the fuse back in and the wiper and sprayer obeyed the switch.
Can anyone here diagnose this?
Is this just the first symptom of something that is going to get worse/continue?
The wiper switch has nothing to do with the door latch/switch/ajar light.
Unless they maybe share the same relay somewhere?
Over lunch, and going through some topics similar to this on my phone, I saw a mention of 'relay', and it stated that once a relay goes 'bad' it CAN possibly continue to send power to its target regardless of the switch position.
Is there some relay or module that is shared by both the door ajar switch and the wiper/washer motors?
And if so - where is it?
I most certainly don't want any electrical problems to go un-fixed in the remote area I live.
Help is appreciated.
Thanks.

wizardpc

Rear hatch wiring is bad. Happens to all of the wires in that bundle. Mine started with the power lock and has progressed to almost all of them. My favorite was the time when I hit the brakes and the rear washer/wiper kicked off

Karl B. Andersen

I do appreciate that video.
I can not, however, see how that relates to that door ajar light the way I described it.
And the fact that it's doing it in conjunction with the wiper.
That said, there may be a ground issue that needs to be located.
I'll know more later this morning.
Thanks.

wizardpc

The liftgate ajar signal is shorting against the wiper signal, activating both.

The liftgate switch completes the liftgate ajar lamp circuit by grounding it. Thus, the wire going to the liftgate switch has 12v power. That wire is 20 ga tan/black stripe.

The rear wiper switch sends power to the rear wiper module. The rear wiper module does not get 12v power to it unless it's supposed to turn on.

Thus, if you take the hot-when-jeep-is-on wire for the liftgate ajar signal, and apply it to the rear wiper module, BOTH will come on.

Karl B. Andersen

That is an excellent description of the possible problem.
It also explains why the wiper switch would not work - it wasn't involved.

May I ask what you mean - exactly - by the wiper "module"? The wiper motor chassis?
Or is there something separate?

wizardpc

It's the wiper/washer unit in the hatch. All one unit iirc.

Karl B. Andersen

Thanks for the information.
That will help.