To be read in the Seinfeld voice: What's the deal with door lock wiring?

Since I acquired a 1997 XK8 convertible the right passenger door lock never worked right. It would do the lock cycling others have run into, so I pulled the lock out to check microswitches. They were all fine.

But here's what I found: the wiring connector on the car has nine pins, and the electrical diagram shows nine wires, but the module only had eight. Opening up the actuator, it was missing a switch shown in the electrical diagram. The actuator is electrically incompatible with the diagram and apparently the car.

It gets stranger because I see people on eBay selling these eight wire lock modules for XK8s. When I send them messages they say modules were pulled from XK8s even though every model year of the car is listed as having nine wires, not eight.

Does anyone know what's behind this? I assumed someone else had tried to repair the lock on my car in the past and used the wrong part, but why so many selling that part confirming that it's right? Are they confusing it with some other Jaguar with a physically compatible lock but different wiring?

It's a real puzzle, and searching the forums I think jjf ran into the same issue here:
https://www.jaguarforums.com/forum/x...-locks-104909/

 

For the sake of completeness, the story is even a bit weirder. The actuator itself seems electrically incompatible with the wiring diagram, but chillyphilly noticed the same thing in the thread below and apparently it ended up working fine.

The real issue seems to be a microswitch missing entirely, one that senses the door's locked status. The BK and Y circuit doesn't seem to be included in my module so I can't even swap just the actuator. That's why central locking would cycle the lock: it never got feedback that the lock was locking.

And as an aside, when I got the car I found someone had gone into the passenger fusebox and apparently tried to short one circuit past a fuse into a completely different circuit. It looked like they'd tried to short the cigarette lighter into the door somehow, maybe in a desperate bid to get the damn thing to lock? Who knows.

chillyphilly's thread
https://www.jaguarforums.com/forum/x...-175483/page2/

 

Could that be because your locks are of the Single Lock variety (Common in the USA?) rather than the Double Lock (Deadlock) ones that are universal in UK.

The additional wire for double locking is the Slate/Blue wire on Pin 1.

 

Hi, astromorg.

There are a few other clues that it's not so simple. For one, I only have two microswitches (from memory here) instead of the three other people in this forum discuss, and I only have three wire bundles coming out of the plug to the module instead of the four I see in others' pictures.

Also, the pinout of my plug seems to have things moved around: the lock status yellow and black are on the motor switch pins. When I get back to my notes I can give a full pinout to show the differences, but it's not as simple as just one missing wire.

That being said, maybe it's all equivalent to just not having double locking. What does double locking actually do on this car?

 

Here are my notes from the 1997 Electrical Guide vs what I found:

According to the Electrical Guide, current goes into the motor on pin 3 and then out on either pin 2 or pin 1 depending on how the motor switch position. On this module current only goes out on pin 2, and correct, there is no wire going to pin 1.

Other people report a third microswitch, as in the link below, but I have only two. I assume their microswitch goes over pins 8 and 9, but my 8 and 9 instead go to the motor switch.

So sure, I can see how these differences might come from the lack of deadlocking, but does my car know not to look for any feedback on pin 1? Since the car side of the connector has a pin 1, is it trying to look for feedback there?

Example link with 3 microswitches:
JagRepair.com - Jaguar Repair Information Resource

 

Double Locking (two presses of the Fob Lock button) sets the lock through an extra position so that if a window is broken, the car cannot then be unlocked by using the internal door handle (Thieves in UK don't give up just 'cos the door's locked on the outside!)

The car is locked by a 12v pulse through the Slate/Green wire, Pin 2 Ground through the Slate/Yellow, Pin 3. This sets the microswitch (that you don't have!) so that the second press of the Fob puts a 12v pulse through the Slate/Blue wire Pin 1 to achieve Double Lock, again Ground through the Slate/Yellow, Pin3.

Unlock puts a 12v pulse through the Slate/Yellow, Pin 3 with Ground through either Slate/Green, Pin 2 or Slate/Blue, Pin 1 depending on whether the car was single or double locked.

In your case, I would think that you have the 12v and ground alternating between Pins 2 and 3 depending on whether you're locking or unlocking, because you have no microswitch between pins 1 and 2.

 

Thanks for the tip, astromorg

I'll be heading out of town for a few days, so sometime next week I'll have to think this through farther and jam wires into the socket to see what the car does (kidding, kidding... mostly).

It's sounding like they've wired these things so that different regions can have different lock modules without modifying the car, if I'm thinking it through correctly. That would be clever, and it would save me having to track down a new, nine wire lock module.

I can't be the only one thrown off by different numbers of wires, so I'll update when I've done some jamming... errr... testing of the car's lock feedback mechanisms.

 

Well, astromorg was completely correct, and I feel betrayed by my precious Electrical Guide

The different numbers of pins on both sides of that connector and the absence of a switch ended up OK. It still seems weird, but it works for me now, and I hope someone reading this thread in the future won't be so thrown off.

In the end I'd been having the same problem pointed out by chillyphilly in his post here with a tiny part broken in the lock actuator. After fixing it, everything's working fine. The wiring difference was a total red herring.

In the thread, VinceCh wondered about 3D printing the part. I thought I'd give it a shot, and so far my 3D printed part is working fine. I printed it out of normal, reasonable quality PLA with pretty common settings. It took around ten minutes to print and half an hour with needle files trying to make sure there weren't any rough edges or crevices that would hang the part up. I REALLY didn't want to take the lock back out again.

I'm attaching the 3D print .stl file here (in a zip file that the forum will let me upload) and I've posted the project to Thingiverse at this address: https://www.thingiverse.com/thing:2912243

If the lock fails soon and I find out it's because of this part, I'll come back and update the thread with that warning. So far, though, I think I'm set!

One final note: boy, that outside door handle ball joint is hard to reattach. If I have to do it again I'm going to try warming the plastic just a bit first.

 

Bit late, but just a thought - if it's a very early car then the pinouts don't necessarily tally with the diagram:

† NOTE: Early production vehicles (-> VIN 003300) have connector pin
numbers that differ from the volume production pin numbers shown.
Use the wire color code for pin identification on early production vehicles.