I kind of addressed this issue in my headlight upgrade thread, but I think it may be more of an issue to itself that may be somewhat unrelated. Recently, my wipers have been acting somewhat funny. At first they just flat out stopped working for no apparent reason. One second I was driving down the road and the next they just stopped doing anything. I thought it might be linked with my HID upgrade, so I checked the wiring and tried moving some grounds around to isolate the circuits and things seemed to be working okay. However, now they seem to work for a while and then just cut out if I leave them on for longer periods of time. For instance, I drive about 30 minutes to work, and if I turn them on when I leave the house they usually make it around 20-25 minutes before giving out and do the same thing on the way home, even with the lights off. Wherever the blade is when the motor stops is where it stays, it doesn't go back down or anything.

To add to the confusion, the other day it was lightly misting, so I didn't have the wipers on all the time, but instead just used the single wipe function every once in a while. Sometimes, the wipers would hesitate to start at all, then move very slow up the windshield, and normal speed back down. Other times they would work just like normal. Has anyone else experienced similar symptoms? Any recommendations on what I should look into (other than a new wiper motor)? I don't mind taking the stuff apart to try to fix it. If it's already broken I'm not going to make it that much worse, lol.

 

I would start by checking the ground connection to the battery. Simple things first.

 

Fuse #3, driver's side fuse box, powers the high and low wiper relays found to the outside of the brake master cylinder. I'd begin by wiggling/cleaning/checking those and the wiper motor connector. After that I'd try swapping each relay, one at a time. One could also wire lamps to the wiper motor BW and BR wires at the motor connector to see if power was failing on its way to the motor.

 

Ah, didn't think of an indicator light, that would be pretty easy and help rule things out. Wondered if it might have to do with the switch somehow, but that would be a good way to check.

 

Oh, from the subject line, I thought you might be referring to a situation like mine the way that they come on for no reason when I start the car, or when I hit a bump in the road.

It is the same way the steering wheel usually comes to the pre set position when I start the car, and other times it just stays in the upright position.

Going back to the 50's and 60's I always used to hear about strange goings on in Jag electrical systems. It seems that there are still some gremlins running loose in the Jag factories.

 

Map00XKR;
Adding somewhat to Beav - the run/stop relay (in front of the fast/slow wiper relay) has its own ground wire (black) as does the motor itself. Maybe check for good grounds.
Because of the intermittent behavior, what you describe sounds as if the wipers are attempting to work but are being interrupted by a failing component or circuit failure.
Also, while misting windshield, maybe run the switch through the fast, slow, flick, and various intermittent settings to further isolate a possible problem or eliminate the various switch positions from the steering column stalk.

 

Oh, I didn't think about relay grounds too. I checked the wiring diagram and tried to pull the wiper motor ground off of my headlight ground since I thought I might be getting feedback from the ballasts, but maybe I haven't isolated it far enough. Although I guess they still cut out when the lights were off once, so maybe when I moved the grounds around I didn't get them secured all the way.

I did try running the switch through all the settings when the wipers stopped in the past with some mixed results. Switching speeds didn't seem to have any effect, but when I changed the intermittent setting from auto to a set speed they started up again. I think that was mainly conicidence though, because the next time when they stopped and I tried that it didn't make a difference. I'll have to look through the diagrams again and see where the relays go.

 

The ground at the relay really doesn't ground the relay itself and is actually attached to the same ground stud as the motor. It supplies ground through the 'slow' windings of the motor's armature when the motor is switched 'off' so I doubt it would have much effect on how the motor performs when it is switched 'on'.

Don't forget that the switch itself is 'fed' a switched ground from the ignition switch which it sends to the BPM through any selected position other than 'Off'.

My experience, fwiw, is attracted to why would they function normally for 20-25 minutes of driving, without fault, if a poor connection was the culprit. Surely a bad connection would intermittently show itself before that amount of time had passed. And why, once the circuit opened, would it remain open? I'm leaning more toward something is getting warm and opening, maybe the circuit breaker inside the motor is malfunctioning? All of this put together is why I suggested the running test lamps idea.

 

Yeah, I did think it was a little weird that it seems to work okay for the most part to start with and has somewhat of a limited "life" so to speak. I haven't done super thorough testing to verify that it always works okay and then fails, but that seems to be my experience so far. I thought about just yanking the motor out and pulling it apart to see if anything was weird inside, but figured I'd see if anyone else had ever had similar issues. I think it has failed for very short periods of time without having been turned on for too long, but usually once it fails it takes it quite a while to recover.

 

It does sound like a short. Are the motors slowing down? or just stopping after running normally? If that is the case, it sounds like they are losing power.

 

For the most part when they fail they just stop wherever they are. However, on a few occasions they will move slowly while wiping up the windsheild, then they usually go their normal speed when they come back down. That has only happened when I have used the single wipe flick on the controls. I don't think I've ever seen them slow down when on any of the intermittent settings.

 

Well, pretty sure it's some kind of short. Brought it home from work the other day and it was just a little misty out. Never turned the lights on from the time I left work, and half way home I did the flick wipe because a car kicked up some spray and the wipers never even moved. Tried the mist option and the pump kicked on and sprayed, but wipers still didn't move. A minute or two later the wipers wiped once when everything was off. I think maybe something is getting wet and shorting or something like that.

Does anyone know if the wipers have a load sensing capability on them? For instance, if your wipers are frozen or stuck for some reason and you try to turn them on does the car sense the extra load on the motor and keep it from working? I figured maybe I had a flakey sensor that was keeping the wipers from moving and when it finally starts working it lets the wipers finish their last sweep despite the fact that the switch is in the off position.

 

I don't know about a short, maybe an open. Normally there's a circuit breaker in wiper motors but the schematic I'm looking at doesn't indicate one. Which brings me to a couple questions: What year and model are we working on? Does it have rain-sensing wipers?

 

It's a 2000 XKR and yes, it does have the rain-sensing wipers, though it will fail regardless of where I use the auto setting or not.

 

Going back to the 50's and 60's I always used to hear about strange goings on in Jag electrical systems.

And into the 70's 80's and early 90's