Volvo wipers won't stop!

2002 Volvo V70 XC
Wipers work fine in fast, regular and intermittent settings. Intermittent works correctly (and the slowest intermittent setting is pretty slow). When set to “OFF” they keep running (basically at “regular” speed).

I had this problem 2 years ago…took it to the dealer…2 (service) hours later they still hadn’t figured out why, so I took the car home and figured there weren’t that many parts involved…so,

I replaced the multifunction switch (what you use you turn the wipers on and select their speed) - no change.

I replaced the wiper motor with a rebuilt one, and that fixed it, except for some very rare glitches…until it started acting up again a couple of days ago.

So, before I replace the wiper motor again (shouldn’t it last more than 1.5 years?), is there a way to diagnose if it’s a problem with an electrical connection vs a problem with the wiper motor? I have access to a voltmeter, oscilloscope, soldering iron, etc.

Thanks for any help!

It’s not going to be a problem with a connection, but the possible culprits include the (park switch in the) motor, the multifunction switch, the CEM (central electronic module), and a couple of relays. It would really be helpful to work with a wiring diagram, though it’s probably possible to common-sense it if you’re familiar with typical wiper wiring configurations.

Thanks Gary!

Your comment jogged my memory - yes, I did replace two relays before, it didn’t make a difference, so I still have the old ones. I’ll swap out the relays tonight.

I have a Haynes manual, which has a “typical” wiring diagram (eg, the wire colors, etc don’t exactly match my car).

The power of Chrysler compels you! The power of Chrysler compels you! …

There ain’t no wiper like a Volvo wiper 'cause a Volvo wiper don’t stop!

If I had to guess, and this would be a SWAG I would say it is one of two possible issues.
The first one is a bad ground. Do this start the car and get out and stare at the headlights. Are they both the same brightness? Is maybe the right one a bit dimmer than the left? If the headlight on the side where the windshield washer pump is located has a bad ground the current from the headlight can feed back through the washer pump and cause the wipers to run.
Disconnect the washer pump and see if the wipes still run. If they stop with the pump disconnected a bad ground is the issue.
The second thing that jumps to mind is a bad steering wheel module. A bad steering wheel module could cause the wipers to run. Do the steering wheel switches work? (radio, cruise). If no then it is most likely the SWM. This is not a DIY repair as the new module has to be programmed.

Ok, the car is apparently monitoring this thread and laughing at me. Wipers didn’t stop for the last 4 days…didn’t stop this morning and afternoon when my wife had the car…then worked flawlessly this evening when I tried to implement your suggestions…

Rick - thanks for the suggestion about the bad ground on the lights - that’s the sort of thing I never would have thought of…

With the wipers working correctly, the lights are the same intensity, and the radio and cruise controls on the steering wheel work properly (so at least I have a baseline comparison…)

Will report back when it’s acting up again…

Don’t just look at the lights from the driver’s seat. Get out in front of the car squat down and stare right at them. A bad ground can make them 20-30% dimmer and trust me you can’t see that from the driver’s seat.

Ok, it started misbehaving again, so I was able to try some of Gary and Rick’s suggestions:

I swapped out the two wiper relays - no change.

The radio + cruise controls on the steering wheel work fine even when the wiper is misbehaving.

I removed and cleaned the contacts on the ground which the wiper motor (and lots of other things) connect to - no change.

I don’t see one headlight obviously brighter than the other one (this is viewed from in front of the car, with eyes at headlight level). This doesn’t change whether the wipers are in OFF position (and running) or in very slow intermittent position. Also, the wipers misbehave whether the headlights are on or not.

I looked into disconnecting the washer motor. The motor is really hard to access, and I don’t see any obvious place where the wires come in (actually, I can’t even see the washer motor - the reservoir covers it too well). The Haynes manual instructions for replacing the washer motor have “remove front bumper” as step 2. There’s probably a way for someone with more experience to access the connections, but I don’t see them. So, rather than disconnect the washer motor, I pulled its relay – that made no difference to the wiper misbehavior.

Also, if I have the (front) wipers are set to intermittent or ON, then when I put the car into reverse, the rear wipers go (as they should). If the (front) wipers are set to OFF, but are running, when I go in reverse, the rear wipers do not go. Hopefully this means its a localized problem to the front wiper and isn’t a problem with the computer.

Any other suggestions, or should I swap out the wiper motor? (or is there another way to check for a bad park sensor on the wiper motor).

Thanks for your suggestions!

I check with a couple of people and none of are aware of any pattern failure on these cars that would cause this.
The fact that the the cruise and radio buttons work prove that the steering module is up and working (there is a safety if this module dies the wipers come on) so it is not the SWM.
The fact that there is not a bad ground at the headlights eliminates that.
It could be a bad park switch in the wiper motor, but the exact same failure on two wiper motors would be very rare.
It is beginning to look like the central electronic module is starting to die, but I don’t want to condem it without running some tests.
If it is the CEM it is spendy

Thanks Rick.

I’ll swap out the wiper motor (a rebuilt one is about $100) and cross my fingers that it will fix the problem. Hopefully it’s not the CEM. If its the CEM, it wouldn’t be the first time a fancy bit of electronics on this car went on the fritz. I had the instrument panel blank out on me and managed to fix it by reworking the solder joints (a replacement is over $1K).