Wipers won't stop!

RBM2010

MEMBER
2002 VOLVO V70
4 CYL
AWD
AUTOMATIC
140,000 MILES

With the wiper switch in the "OFF" position, the windshield wipers run continuously (just slightly more slowly than in the "LOW" position). The problem is a bit intermittent - sometimes will work correctly for a day, then back to running all the time.

I replaced the wiper switch. Worked ok for 2 days, then back to running continuously.

Checked the ground connection for the wiper motor electrical connection - voltmeter said it was ok; cleaned ground lug where it bolts to chassis (voltmeter still says ok); wipers still run continuously.

Have seen similar symptoms in other manufacturer cars online as being due to bad park switch in the wiper motor. Not sure if this is applies to this car (2002 Volvo V70 X/C). In intermittent mode, the wipers do stop at the correct position.

Any help would be appreciated. I'd prefer to not replace wiper motor unnecessarily.

Thanks!

7 Replies

DAVE H

MECHANIC
13,384 POSTS

Hello .. thanks for the donation .. much appreciated

Check the rain sensor is giving the correct voltages !

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Tuesday, July 27th, 2010 AT 2:29 AM

RBM2010

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4 POSTS

Thanks for the prompt reply!

I don't think this year/model has a rain sensor.

I think it should be at the top of the windscreen, behind the mirror. I looked there and didn't see anything. I took a photo just in case and uploaded it to

www. Chem. Umass. Edu/ rbmetz/Volvomirror. JPG

(mirror is to left of photo)

If there is no rain sensor, what's the next thing to check?

Thanks,

Rick

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Tuesday, July 27th, 2010 AT 7:38 AM

RBM2010

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4 POSTS

One more thing:
I've already replaced the wiper relays FST1 and FST3.
That made no difference.

Rick

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Tuesday, July 27th, 2010 AT 9:01 AM

DAVE H

MECHANIC
13,384 POSTS

Information about the position of the control stalk is transmitted to the central electronic module (CEM) on the controller area network (CAN). The central electronic module (CEM) also receives a signal from the wiper motor if the wipers are in the park position.
The central electronic module (CEM) also monitors the windshield washer reservoir level via a level sensor in the reservoir. The switch in the level sensor closes if the level falls below one liter. A text message indicating that the windshield washer fluid needs to be topped up then lights in the driver information module (DIM).
The power supply for the rear windshield wiper is via a directly connected relay on the rear electronic module (REM). Other wipers and the washer motors are supplied with power via relays in the engine compartment.

There are diagnostics for the windshield wipers.

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Tuesday, July 27th, 2010 AT 7:41 PM

RBM2010

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Dave,

Thanks for all of the information. I'm really hoping it's not some weird malfunction in the CEM.

You said that there are diagnostics for the windshield wipers. Is there a flowchart I could work through to try to isolate the problem in a logical way?
If so,
- where can I find this flowchart (do I need to go to ALLDATA to get it?) And
- can I make the required measurements using a voltmeter and oscilloscope, or do I need a scan tool or other specialized equipment?

When this problem first occurred, I took it to the Volvo dealer, and, $160 later, it was working fine after they had "cleaned the contacts, " but they weren't very optimistic that they'd actually fixed the problem and, the next day it came back. They also suggested I replace the relays (which I did). That's why I was trying to work on it myself - it sometime works ok for a day for no reason, then goes back to malfunctioning, so it seems like the kind of problem a shop could put a lot of time into without fixing the problem.

I couple of other pieces of info:
The car's battery is ok (had it tested).
The headlight wipers/washers work as they should.
If the wiper switch is in the Intermittent/Low/High position and I put the car in reverse, the rear wiper runs (as it should). If the wiper switch is in the OFF position (but the wipers are running) and I put the car into reverse, the rear wiper doesn't run.

Thanks,

Rick

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Wednesday, July 28th, 2010 AT 12:21 PM

DAVE H

MECHANIC
13,384 POSTS

Wiper/washers for the windshield and headlamps

The right-hand control stalk is moved downwards through three positions to operate the windshield wipers. The steering wheel module (SWM) (3/130) transmits information via the control area network (CAN) to the central electronic module (CEM) (4/56) about the selected position. The central electronic module (CEM) then activates relay 2/91 which supplies the wiper motor (6/1) with power in position 1. If high speed wiping is selected, relay 2/90 is also activated to power the motor in position 2.
The central electronic module (CEM) receives a signal from the motor when the wipers are in the parked position so that the wipers can be stopped in the correct position.
For intermittent wiping, the process is the same as for low speed, but the time between each stroke is set using the ring on the control stalk to one of eight positions between 1 and 27 seconds. The central electronic module (CEM) controls this once it has received information about intermittent wiping from the steering wheel module (SWM) via the control area network (CAN).
The windshield and headlamps are washed when the right-hand control stalk is moved towards the steering wheel. The steering wheel module (SWM) transmits information to the central electronic module (CEM) via the Control area network (CAN) to activate washing. The central electronic module (CEM) activates the relay 2/92 which powers the pump motor (6/2) and wiper motors (6/3-4) for the headlamps.
The central electronic module (CEM) receives a signal from the level sensor (7/5) in the windshield washer reservoir so that it can check the windshield washer reservoir level. The switch in the level sensor closes if the level falls below one liter. The central electronic module (CEM) sends the signal to Driver information module (DIM) (5/1) via the controller area network (CAN). The driver information module (DIM) displays a text message indicating that the windshield washer fluid needs to be topped up.
The tailgate wiper (6/32) (V70/V70XC) is controlled by the rear electronic module (REM) (4/58). The rear electronic module (REM) receives a control area network (CAN) signal from the steering wheel module (SWM) via the central electronic module (CEM). The rear electronic module (REM) then powers relay 2/16 to start the tailgate wiper. The tailgate wiper is powered via relay 2/72.
The tailgate wiper can be programmed so that it is activated if the windshield wipers are on and back-up gear is selected.
Rear windshield cleaning is activated when the right-hand control stalk is pushed away from the steering wheel. The steering wheel module (SWM) sends signals via the control area network (CAN) to the central electronic module (CEM) to activate rear windshield washing. The central electronic module (CEM) activates relay 2/93 to power the pump motor (6/30). At the same time the rear electronic module (REM) activates the tailgate wiper.
The wipers only operate at low speed if there is a fault in the control area network (CAN). If this is the case, the central electronic module (CEM) receives a directly connected signal from the steering wheel module (SWM).
There is no Limp Home function for the rear windshield washer and wiper.