Greetings from a new owner. I recently purchase a 2007 S80 V8 AWD It is in good condition but was cheap because of one issue I thought would be easy to solve. The wipers don't work at all. I have searched various forums and found there are a couple of issues reported a) Wipers don't work and b) Wipers won't stop.


Now that weather in the North East USA is finally getting warmer I am taking an interest in trying to get the car ready for the road and have been doing some diagnosis.


Firstly I have invested in an iCarSoft VOL II and found that the car is free of all OBD and DST codes except for one from the CEM


CEM-B113187 Wiper Motor Module Bus Signal/Missing Message


I googled that and found a couple of hits on Swedish and Dutch forums both related to either one of the issues - won't work at all or won't stop.
These issues seem to related to many different Volvo models, not just the S80


I have pulled the wiper motor assembly off the car and put a multimeter across the supply connector. This is a 4 pin position with only three pins actually used. This is where I am looking for some guidance from the experts of this forum. There are 2 wires that I'm assuming are the live and the ground. One is red/green and the other is black/red. There is a third, thinner wire, yellow/blue which I believe from my research goes to the CEM. I have found that regardless of the stalk lever position, and even whether the ignition is on or off, there is 12V across the red/green and black/red wires. Is this normal? It would lead me to assume that all control of actual operation/speed/intermittent etc is done by signals from the CEM on the yellow/blue wire. It also leads me to assume that the buried and inaccessible 30A wiper fuse (F9) must be OK. Can someone please guide me on this - let me know how the system is conceptually supposed to work and what to check next? Is it possible to 'bench test' the wiper motor off the car by supplying 12V to the above mentioned terminals?? Or do you need the signal on the third wire to make anything work?


By the way I've read about possible interaction with after market HID lights and also the alarm siren. I believe the lights are factory, and the alarm siren works just fine! I am also aware there was a recall (4/29/2009) on 2007/2008 models for this very problem but so far as I can ascertain this car was 'fixed' (How would I know for sure?)


Thank you in advance for any words of wisdom. This is turning out to be a very odd issue


Norm

 

In the interest of providing an answer to this apparently common issue with wiper motors on Volvo S80's and V70's and possibly other models from the last 10-12 years I have solved my issue by purchasing a replacement wiper motor from eBay which came from an identical car.


As near as I can determine the cause of either issue which is frequently reported - either a) Wipers won't stop or b) Wipers don't work at all is because on these cars all the wiper stalk actually does is to send different signals on the LIN bus from the CEM to the WMM which is a part of the actual wiper motor assembly. I was puzzled to find a constant 12V across the live and ground wires going to the WMM. I am still not sure whether is always true or just because the CEM had not received the parked signal from the WMM. Either way I'm told the reliable way to determine whether an issue is because of the WMM (cheap to replace) or the CEM (not cheap)is to use a digital voltmeter across the yellow/blue LIN wire and ground as an assistant operates the wiper stalk. You should observe different voltages indicating the presence of signals to the electronics in the WMM


There was nothing obviously wrong with the wiper motor assembly on my car. Since I had ordered a replacement I did remove the clips holding the WMM to the motor and did then notice a faint burnt smell but no obvious signs of failure. The motor itself did still work when 12 volts were applied across the brushes, but would never respond to any signals when hooked up to the connector from the car. As soon as I hooked up the replacement everything worked as it should


Hope this helps someone


Norm