1998 S70 Door Lock Actuator Issue?

Post by **dosbricks** » 06 Dec 2015, 13:11

It's pretty obvious I'm not a smart engineer, but....you are correct that the motor is not dead and the resistor is not completely dead.
What I think they are saying is that the resister inside the motor which prevents it from overheating is aged and is weakened, and resistance goes up when the ambient temp is higher or the lock has been used repeatedly in a short time space. Also there is supposedly a different load on the motor for lock and unlock operation. With that thought in mind, if resistance is increased from age, the motor still gets enough power to lock that door, but the resistance is a bit too high to allow sufficient voltage to perform the unlock operation.

I have the exact same issue with my wife's S70 when the weather is warm. After watching the video you linked to, I'm inclined to take the actuator and motor apart and replace the resistor with a bridge. It looks like the resistor is mainly there to protect the motor from heating and seizing if it's abused--example: two people horsing around and holding down both the lock and unlock buttons at the same time. But even if the motor did overheat, it's doubtful it would be a safety problem--just a killed little Mabuchi motor. The other route is to just replace the motor as you suggested.

Post by **cn90** » 06 Dec 2015, 13:36

Thanks dosbricks, your explanation makes sense as it takes more juice to go up than going down.
Hey it is easier walking downstairs than upstairs...lol.

Right now, this issue goes to the back burner b/c the car is being driven by my high-school boys to go to school.
They just have to reach over and pull the knob up.
I want them to "deal with life" for now ha!

Post by **dosbricks** » 06 Dec 2015, 14:02

I hear you. Just getting all the major mechanical stuff whipped into shape on these "almost classic" Volvos has occupied my spare time for most of this past year. The minor inconveniences have had to wait.

Post by **erikv11** » 06 Dec 2015, 20:11

This sounds like some of you have the "interior pin" broken on the door lock mechanism. I have three failed actuators in the garage, the reason I kept them is all three have working motors, all have suffered a failed/broken/disappearance of the little pin the the motor pushes for unlocking. I will put together a reply over in the other thread: https://www.matthewsvolvosite.com/forums ... 0&start=28 with some pics.

Post by **cn90** » 06 Dec 2015, 20:40

Hi erik,

Could you post some photos of the pins?
I search the web but could not find info on the pin?

1998 S70 Door Lock Actuator Issue?

Re: 1998 S70 Door Lock Actuator Issue?