Definitely finds ground through the rack. It’s a single wire switch. You might not need a new contact. If it just needs adjusting or bending it can be put back.
Erica, what does the knob on the bulkhead do? Looks like it applies tension to the mechanism but for what purpose? Scott had alluded to it in one of his replies
Look at the above photo, left hand side. There are two pieces arranged like a pair of scissors. The hand crank drives a threaded cable which cause the scissors to move in relation to each other. This causes the two contacts to move in relation to each other. So instead of physically adjusting the contacts, you’re physically moving the steel parts the contacts are attached too, same net effect but you don’t have to open the panel. The idea was, the contacts were set at the factory and if the user needed to adjust in the future after changing wiper blades, they’d turn the outer crank instead.
I was speculating whether the path to earth (which keeps the wiper wiping), made whilst the wiper wipes around the semi-circle (and before it falls off of the edge), was broken part of the way around the semi-circle, rather than running over the end of the semi-circle and stopping the wipers then.
The other thing to confirm is whether the wipers start their reverse direction wiping but don’t finish it in the right place (meaning instantly changing direction upon switching, not whether they complete a full back and forth cycle, or whether they just stop dead upon switching.
The wipers are 12v all of the time that the ignition key is turned and their movement is always controlled by switching to earth. To seen that mechanism, call up the late Dick Vandermeyden’s excellent article which is available else where on this site.
kind regards
Marek
Makes sense and I had seen the connection earlier. When I turned the knob, nothing happens. So I’ll probe around, check continuity maybe add jump power, remove the contact, etc. thanks for your help Erica.
Thanks Merek. This will all be a part of my probing today. I appreciate the ideas.
The knob may not be functioning. They freeze up, or can break. You’d need to watch it while someone turns it to know fir sure what it’s doing. I never use it. It’s kind of junky.
I have the same problem W/ a series 2 FHC. Also came out of nowhere & also always worked correctly previously. Would I look for the same copper wire you’re
describing here in a Series 1? I’ve never noticed one. Can’t Remember if I bought a new wiper motor from XKs or had them rebuild mine many years ago during total reconstruction. After installing, it worked perfectly until one day. My blades stop more vertically when parking. Bought a new toggle switch & checked all wires. I unplugged the wire on the farthest pin back.
The wipers will stop where ever they are when I push the rocker switch off. So if timed correctly I can get them to lie flat @ the bottom.
Michael Caro
I’m not sure how the parking mechanism works on a S2 car. I think it’s pretty different. They have different motors also.
Ok, I had continuity from the RLG to the mechanism. Reconnected the battery which has been out since replacing the fan motor, which BTW works awesomely now, and started the wipers. When parked, if I pressed down, they would come back to where they wanted to park. Don’t know what that means for sure but Merek mentioned trying that. I went and started adjusting the switch by loosening the screw. It was originally all the way to one side and had been there forever. As I moved it, it got better until I reached a point where the wipers would not shut off even with the toggle switch. Backed it off a bit and we’re good. The screw now sits about the middle of the slot. A long way from where it has been forever. Scratching my head but it works it is becoming my nemesis as well 
Thanks to all for their help!
Maybe because of the adjusting you did with the bulkhead knob? As I said, they make the same type of change but in different ways, so to cancel that out using the switch adjustment, it would end up in a different spot.
Could be, but I didn’t adjust that until after the problem started. Might be my fat arm in there when reattaching the washer nozzle may have knocked the arm it pulls on and knocked it out of adjustment
Mine had a black wire connected to the drivers end of the wiper rack that was grounded to a bolt on the firewall behind the driver’s instrument cluster.
I’ll stick my flashlight up there and see if I can find that. Could very well have it, but the dash top is back on and speedo and tach in as well. I’d rather not disturb that again.
This thread captures what I learned about the wiper motor ground wire. (LHD) It didn’t actually seem to make a lot of difference (wiper worked before and worked the same after connecting it) so it’s likely true the motor grounds itself via the mounting or an alternate path through the wiper mechanism.
Dave
Dear Dave,
the s1 motor doesn’t have an “alternative” grounding path, any more than it runs from some alternative battery. The path to earth is clearly defined in the three diagrams at the end of the Dick Vandermeyden article and only those paths make it run correctly. Supplying alternative grounding will most definitely make things run incorrectly. What you sound like you are describing is an intermittent fault caused by corroded connectors, e.g. a bit of verdigris in the dash switch, because they are not used/cleaned often enough.
kind regards
Marek
This is exactly so…and .in order for this to happen, however , the wiper switch MUST have the G jumper from the fuse block # 6 or 7 ( they are electrically connected.) If its not connected then the motor will not park properly I fitted my motor 2 month ago,after a complete dismantle and clean up.All this also assumes that the RLG. NLG, YLGand B wires are correctly located on the wiper switch.!
Marek, the diagrams show the connection of the ground in offhand way after the switch. Just like the service manual, it doesn’t specify whether through a wire or through the body of the wiper mechanism. On the center mechanism, which contains the park switch, there is no wire to ground even though the diagrams show a ground after the switch. So one has to assume that here is a wire somewhere, which appears to be from the left mechanism or through the center mechanism itself. It appears it can be either way based on Dave’s observation that it still works without the ground wire connected
Could one of you in the know please post a picture of where that pesky park-adjusting knob comes through the firewall / bulkhead?
Perry, I can but I just took my car to storage as we have sold our house and close in two weeks. I’ll go over tomorrow as I take more stuff over tomorrow if someone hasn’t responded by then.