Dead headlight wiper

gherman · Post by **gherman** » 11 Jan 2011, 13:17

Bill, et al.

First off--great site. Learning a great deal about my 2000 S40.

I've read all I can on the wiper motor on the site. I just have one unanswered question.

The drivers-side headlight wiper is dead. I can turn it loosely by hand. It makes me wonder in there might just be a poor connection or a loose nut. Is there a way to clean the connector or tighten a nut somewhere without ripping into the bumper? Where is the connector located?

Thanks!

Glen of Chicago

Post by **billofdurham** » 12 Jan 2011, 12:09

I can turn it loosely by hand

Do you mean the whole unit turns or just the arm and blade?

Bill.

Post by **jimmy57** » 12 Jan 2011, 12:14

First thing to do is to gently pry up the cover over motor end of wiper arm. This covers the end of motor shaft and the nut that holds arm to motor shaft.
The shaft is tapered with very fine splines and the torque of the nut is not too high so the arm coming loose from motor is a protection from burning out motor if the arm gets iced up and stuck in its park position. The motor will shear a little metal out of the arm. Tighten the nut but not too tight. I can't find that torque spec easily but I recall it being 20-28 inch pounds. That is about the torque you can do with a nut driver handle when your palm begins to sting....

I guess a good question to ask before you go too far is if you can hear the motor run when you operate the W/S washers to get them to operate?
The nut can be tight but have motor gears stripped.

gherman · Post by **gherman** » 14 Jan 2011, 12:26

The arm was loose. The shaft isn't budging. I'm taking the whole unit out later today and seeing what's going on inside the works. Will update.

Post by **jimmy57** » 14 Jan 2011, 14:02

If the wiper motor is good it will not turn by hand due to the gears inside. Does it now work if you operate washers as it should?

gherman · Post by **gherman** » 15 Jan 2011, 05:52

Thanks Jimmy. Took the whole thing off, opened it up, and fiddled with the contacts per instructions here:

http://www.volvoforums.org.uk/showthread.php?t=51146

It had some great photos; however, didn't work out. Another thread on the same site had instructions on cleaning the motor contacts:

http://www.volvoforums.org.uk/showthread.php?t=50577

I may give it a try if feeling ambitious, but when I had it out yesterday, I pulled the wee motor and ran some voltage throught it. It turned ok. I may be chasing squirrels here.

gherman · Post by **gherman** » 16 Jan 2011, 04:25

So here's the coda to the tale. I opened up the motor, and made sure it's all clean inside. It runs like a horse when hooked to 12v. I put it back into the housing and ran 12v through its contacts. It ran and then faded. Then I noticed this 5mm square thing between some funny contacts above the motor. I took that out and tried to fgure out what this mystery wafer was. It measured 12 ohms between its faces, but behaved more like a capacitor in-circuit.

The motor ran better without it, so I did what every maverick mechanic would do--bypassed it. All runs well now; however, not as originally intended. I have to park the wiper arm after its cycle by giving the windows an extra squirt. Hey, if I didn't want a quirky car, I would have purchased a Honda. Bless the Swedes.

I'm sure something will burn out or act strangely. If anyone can identify the offending wafer, I's love to know what it is.

Post by **mikealder** » 16 Jan 2011, 05:23

It probably is a capacitor and connected accross the motor terminals to reduce interference from the motor getting back in to the cars electrical system, quite often when these caps fails they go short circuit and take the fuse out, it sounds like yours is simply breaking down and dumping voltage to the point the motor won't run.

As you have removed it I wouldn't worry too much unless you get a load of interference on the radio when you operate the screen washers - Mike

gherman · Post by **gherman** » 16 Jan 2011, 07:46

Thanks Mike. I was so curious I looked at the wiring diagrams. The S60 shows a diode; the S40 has nothing.

Post by **jimmy57** » 16 Jan 2011, 13:08

On a lot of motors like 240 lock motors and even newer volvo door lock motors, there is a PTC resistor device that acts as a self-resetting circuit breaker. I haven't had headlight wiper motors apart that many times and in those cases I discovered broken gears or burned windings or broken or worn out brushes so the investigation of anything else stopped.
If that is what that device is they are notorious for getting some corrosion on the contacts for the PTC and then you get the short run then shut down.
usually it's a sand, grease, bend contacts for tighter contact type fix.
This feature is why you can't cycle the door locks on 240's and 88 and older 760 and 740 models.
As a matter of fact I need to investigate it on my v70xc since it has the wiper stops in wrong place thing on one of the headlights if I wash two times in a row.