Headlight Wiper Actuator Repair

Post by **rolsen11** » 02 Mar 2025, 15:33

Late last year I disassembled and repaired the drivers side headlight wiper actuator in my 2000 V70. I took some photos of the process but haven't posted them anywhere until now. There are tutorials online about how to get the actuators out of the car.

The component that fails is the solid state fuse that sits between 2 copper strips. The fuse tends to corrode or otherwise just go bad.

The hard part when it comes to disassembling the actuator is getting the plastic cover off. I used several razor blades to push the tabs down and dig into the plastic to keep the tabs held down (it should go without saying, but if you also decide to use razor blades be very careful to not hurt yourself).

Once you have the cover off, you will see a gear with an arm, the motor, and the fuse next to the motor.

The only thing we need to worry about for this repair is pulling out the old fuse and soldering the new one to each strip. The metal plate assembly that contains that plastic gear with the arm can be removed for easier access. Be careful not to change the position of the gears as this can affect the parking function of the actuator.

BE CAREFUL with the position of this specific gear. It is what tells the actuator when to park. If it gets pulled out of position you will have to finick with it for a while until it's in the right spot. You can test the function of the actuator by plugging it into the vehicle harness and operating the windshield washer switch before putting the actuator into the car.

Try your best to get the copper strips moved out of the housing for more clearance. The new fuse can be found from Digi-Key with the part number RGEF400 made by Littelfuse. It's coated and has 2 solder leads rather than being an uncoated square like the old one. Solder each leg to each strip like shown.

MAKE SURE THE COPPER STRIPS DO NOT TOUCH EACH OTHER AFTER SOLDERING. This would bypass the fuse and the motor can burn up if the wiper arm ever gets stuck.

I didn't get a picture of it, but I used 2 pieces of plastic and liquid rubber to insulate the otherwise exposed solder and leads from ever touching each other.

It also wouldn't hurt to put new grease in the actuator as the old grease is over 20 years old now.

Post by **jreed** » 02 Mar 2025, 16:27

Beautiful write up with great photos... well done! Thank you.
I wonder what material the old fuse was made of? I'm guessing it is a material with a PTC (positive temperature coefficient) resistance property. Were the copper contacts just pressed against the old fuse, or was there a bond between the metal and the fuse?

Post by **rolsen11** » 02 Mar 2025, 18:46

That's exactly what it is! The old fuse is just pressed in and held by the friction and compression forces from the copper strips. Due to likely corrosion, the old PTC fuse will gain its high resistance value far too soon, which is why the failure mode is the wiper arm moving very slowly at first and then stopping at some random point before the wipe cycle can finish.

Post by **matthew1** » 02 Mar 2025, 20:49

@rolsen11 this is outstanding. I put it in the Volvo Repair Database and made your account MVS Contributor. Let me know if you want the standard Contributor avatar.

Usual notice: anyone, if yours or someone else's writeup should be in the VRD but is not, let me know.

Post by **rolsen11** » 03 Mar 2025, 18:52

Thanks! I'd rather the information I learned researching this repair go on to help others than just rot in my head forever. I'll continue to do that as I keep tinkering with things on this old brick of mine

.

Vova585 · Post by **Vova585** » 03 Mar 2025, 20:38

Quick question. I heard that tabs are notorious to break when you attempt to open the unit and also that seal might not be great after you put it together. Would you recommend to put some form of windshield silicone for better seal? In retrospective, would it be easier to make bend cooper strings together and use crimp and seal 4A fuse outside prior to connector?(looks like it is 3 wire design so possibly power, ground and memory? Will need someone with more time to look that up. Just thought it might be easier to change fuse that way than to reopen unit). Thank you for writeup.

Post by **foggydogg** » 04 Mar 2025, 11:06

My solution - on every P80 I've ever owned - is to unplug them. If the weather is that snotty I just stay home.

Post by **scot850** » 04 Mar 2025, 16:45

Nice write up and I always appreciate it when folk take the time to share their success with us!

I can't say that corrosion of the thermistor has ever been an issue that I have seen. It is just the resistance of the sandwich material between the plates that changes with time, just like rubber in tires. Anyway, the solution is clever.

For those of us that live in areas where these units working can be a life saver, we like these units to work reliably. When the roads get sloppy here with our chinook warm winds, we can drive as little as a mile and our headlights and coated with dirt.

It is a shame there is no where we can buy the tiles themselves which would make the repairs so much more simple. I have bought motor and brush sets from Ali Baba that have these tiles in them, but not found only the tiles.

Question: How did you know what value of component is required? I'm not electrical or electronic knowledgeable, but does this component work in the same why as the original parts?

Again, thanks for your great write up.

Warming the unit can help to reduce the breakage of the tabs on these components. Gentle use of a heat gun, or even a hair dryer can soften the plastic to make it less brittle.

Neil.

Post by **rolsen11** » 06 Mar 2025, 20:32

scot850 wrote: ↑04 Mar 2025, 16:45 Nice write up and I always appreciate it when folk take the time to share their success with us!

I can't say that corrosion of the thermistor has ever been an issue that I have seen. It is just the resistance of the sandwich material between the plates that changes with time, just like rubber in tires. Anyway, the solution is clever.

For those of us that live in areas where these units working can be a life saver, we like these units to work reliably. When the roads get sloppy here with our chinook warm winds, we can drive as little as a mile and our headlights and coated with dirt.

It is a shame there is no where we can buy the tiles themselves which would make the repairs so much more simple. I have bought motor and brush sets from Ali Baba that have these tiles in them, but not found only the tiles.

Question: How did you know what value of component is required? I'm not electrical or electronic knowledgeable, but does this component work in the same why as the original parts?

Again, thanks for your great write up.

Warming the unit can help to reduce the breakage of the tabs on these components. Gentle use of a heat gun, or even a hair dryer can soften the plastic to make it less brittle.

Neil.

Interesting, I figured that the material wouldn't degrade over time because it's a property of the material and that a small amount of surface corrosion would instead be what caused it. Perhaps you're right about that. I'm no material scientist haha.

I wish I could take credit for sourcing the part, I found a similar component selected by a user in a Saab forum from many years ago. Long enough ago that the part they selected was discontinued. This one I selected was the closest I could find on todays market. Even though it's a different form factor, it is functionally identical to the old part. My hope is that it should be a more reliable part as it is coated and soldered rather than being uncoated and connected with surface contact.

Post by **rolsen11** » 06 Mar 2025, 20:42

Vova585 wrote: ↑03 Mar 2025, 20:38 Quick question. I heard that tabs are notorious to break when you attempt to open the unit and also that seal might not be great after you put it together. Would you recommend to put some form of windshield silicone for better seal? In retrospective, would it be easier to make bend cooper strings together and use crimp and seal 4A fuse outside prior to connector?(looks like it is 3 wire design so possibly power, ground and memory? Will need someone with more time to look that up. Just thought it might be easier to change fuse that way than to reopen unit). Thank you for writeup.

With enough patience the tabs shouldn't break. Unfortunately I did break one, but that was a result of me getting impatient and trying to quickly pull the last tab free. Had I taken a little more time I would have broken no tabs.

Using a small amount of sealer isn't a bad idea, if it offers more peace of mind I would do it. You just don't want any of it to spill over and onto the gears if too much is applied.

That's an interesting idea putting an inline fuse into the harness. It would certainly make potential replacement easy. If you were to take that route, I would make sure to attach those copper strips together very well so there is no chance of a voltage drop or of them ever coming apart. You would want that inline fuse to be well sealed as well of course. 4A makes sense as the new PTC I used is rated up to 4A as well.