Windshield wipers recently gave up. Were behaving fine except for the PARK function. They did not stop while in use, but worked one day, did not the next.

I've pulled the unit, cleaned all connections at the firewall and on the park switch. Park switch was separated at the seam. Opened, cleaned and rebuilt the park switch. Bonded it back together and tested its action. Switches as designed. Still no wiper action.

Preferring to work backwards from the end of the chain, I want to to start at the firewall connection and confirm proper power arriving on the pins, but I don't know what the expected behavior is.

The firewall wiper connector has 8 pins in two vertical columns of four. Im a'signing top starboard pin as 1S. Top port pin as 1P and counting moving down each collumn.

1S 1P
2S 2P
3S 3P
4S 4P

Ignition OFF
all pins carry ~.01v except pin 2P which is always GROUND.
Lucas!

Ignition in RUN.

Wiper switch set to DELAY.
4S is 12v.
2P is GROUND.
All others <1v.

Wiper switch set to 1.
2P is GROUND.
3S 12v.
4S GROUND.
All others <1v.

Wiper switch set to 2.
2P is GROUND.
2S 12v.
4S GROUND.
All others <1v.

That seems correct to me from what I can find on the pinout. Anyone see a problem here, or is my motor suspect?

 

Coincidentally, I was working on wiper motor yesterday. Though looks like my situation is slightly different than yours. Wipers were "moving" when turned on, but barely. Like a turtle crawling. Barely swiping left and right. Cleaning contacts did not improve the situation much.

So, I replaced the motor with another one from my '86 xjs. Now wipers are swiping a lot more energetically! (Like they are supposed to do.)

Anyway, in my situation the issue was the dying motor and replacing it solved it.

 

Well there's your problem right there.

 

Revived. And working park function as a bonus.

 

Oh yeah they all do that! Amazing they're meaty enough to repair but crappy enough to break in the first place.

Make sure the drain is clears and get a a new plastic cover to keep it dry: http://www.sngbarratt.com/ProductDetails.aspx?id=aca93f4b-11b7-47f3-905b-04f114fe097d&b=US

 

Thank you for the link! Mine was toast.

my well was pretty clean. Some rust in the corners. Cleared, rust treated and resprayed. Solid now.

 

The wiper/air vent inlet in the scuttle is the worst design I have ever come across. The drains are not at the lowest point allowing water to pool in the corners. There is NO easy fix. The only way to stop water pooling is to drill holes at the extremities which requires removal of the front fenders.

Good work BTW.

 

JigJag,

What did you actually do to resurrect the wiper motor?

(After succussfully installing the motor from my other car to replace the dying one, I might want to attempt to repair the one I took out. To keep it as a spare...)

 

Two long bolts on the end hold the whole motor together. The brushes are retained in their tracks and won't fall out. The rotor pulled out with the stator casing very easily. Pulling the rotor out of the casing is easy but weird because magnets. Careful. Theres a small cap on the screw end of the rotor shaft, and a ball in the other end. Don't loose them.

When you're cleaning up the rotor don't mess around with the windings. They're fine. I wire brushed the rotor armature rust, and brushed on straight phosphoric acid. This is the active ingredient in rust converter products. Wire brush, acid, wire brush. Completely rust free in 10 minutes. I blast the Ph acid off with ether. Great solvent, ether, removes everything and is completely gone in seconds.

000 steel wool shined up the commutator and the shaft. Wire brush all the casing interior. Compressed air to blast everything off because magnets.

The end cap bush was almost seized to the rotor shaft with rust. Wire brush, acid, blast it clean.

The board holding the brushes was heavily corroded and there was some "boiling" of the bakelite by the red brush and darkening by the blue brush. A fine steel brush on some of the heavy rust at the wire join, acid, toothbrush scrub, ether rinse. Shiny! Dunk those screw-barnacles in acid and wire brush and you might think I bought new screws. Some dielectric grease on the brush tracks, springs and wire joins to keep things from going crusty.

To reassemble, you'll need to retract the brushes to get the commutator back in between them. I ran thread loops around each brush and out the sides of the casing to pull them back and duct tape to hold them there. Three are too many to hold without a helper.

Grease the bushings and shaft. The casing and rotor slide back in without any fuss meshing the gear. Pull one end of the strings to pull them out and release the brushes and bolt it back together.