XK8 Gurus,
I posted this on another forum but thought I would try this resource.

I need help with a malfunctioning driver door window in a 97 XK8 coupe with 184,000 miles that I am restoring. It now runs great but the driver door window is acting up.

Here are the original symptoms and observations:
1. Driver window (DW) worked initially.
2. I added a simple battery cutoff switch to the negative battery terminal.
3. I used the battery cutoff switch a few times and then the DW started misbehaving.
4. With press of the DW down switch, the window went down completely but with press of the DW up switch the window rose about 8 inches. Another press of the down switch, the widow went down and stuck in the down position, unresponsive to switch presses.
5. At this point, when I press the up/down DW switch, the window does not move at all but the door lock actuator makes a clunk noise. The passenger window and switch behave normally.
6. I removed the driver door latch and checked the micro switches, which seem to be working normally. I get a proper door open message on the dash.
7. I replaced the driver door control module with a used module with the same part number and replaced the driver switch pack. But there was no change in behavior.
8. I removed the door wire loom,
checked all wires thoroughly by inspection and resistance on a multimeter (always less than 1 ohm), and inspected the connectors.
9. I jumped the OB and OU colored wires to the regulator motor and was able to raise and lower the window fully without difficulty, indicating that the regulator motor is OK.
10. I replaced the wire loom, inspected and cleaned the wire loom’s connection to the body. But no change in behavior.
11. I did a ”hard reset” of the battery but no change in behavior.
12. Battery voltage with key off is about 12.8V and with engine running it is about 14.8V.

QUESTIONS:
What would cause the driver door lock actuator to fire with a press of the up or down window switch?

Could it be that the replacement door control module is also faulty?

Could the problem be in the body control module or security lock module or connections between them?

What would you suggest as a next diagnostic step?

Thanks much,
DrDan
97 XK8 coupe black on black
Pacific Northwest USA

 

The battery cut-off is probably not your best bet. There are a number of things the car needs permanent power for, like remembering things. The OBDII monitor status is one category, along with fuel trims. The other one is the limits to the windows. Try and press the window down button and hold it a bit until you heat a faint click. Then roll the window up and hold until the same click. This tells the control module what the limits are. It should then work as expected for as long as the battery stays connected and is healthy.

As you described your windows not working at all, there seem like there are other issues, but you can try that window reset procedure at no cost.

Best of luck, keep us posted.

 

XK8 gurus,

Thanks for the advice. Windows won’t move, so using the window rest procedure won’t work at this point.

This is my current situation:

Using info from posts at JaguarForum.com and a nice wiring diagram from Alldata.com that is a little easier to follow than the Jag diagrams, I decided to try bypassing the driver door switch packet to see if I could get the driver window to work. Recall that jumping 12V into the OB and OU colored wires moved the window up and down normally.


I disconnected the driver door switch packet from the multi lock 40 connector and located the brown white (NW) wire, black orange (BO) wire, and the black green (BG) wire at the rear of the connector. With the engine running, I measured 12+V on the NW wire to ground. I then jumped the NW wire to the BO wire and the window rose to its top position. I then jumped the NW wire to the BG wire and the widow went down to its lowest position. I repeated this several times successfully.


I reattached the driver switch pack and the driver window went up and down twice. The passenger window would not respond to the driver up/down switch.


I removed the switch pack again, tried jumping the driver window as above and jumping the passenger window but now neither of them respond to the jump. My multimeter says I’ve lost the 12V power on the NW wire. I understand this NW wire connects directly to a pin in the connector where the wiring loom connects to the body and does go through the driver door control module.


QUESTION: Why did I lose power on the NW wire? Blow a fuse? If it’s a fuse, which one? I don’t see a fuse dedicated to the windows in my electrical diagrams. The 25A fuse for the driver door module, located in the driver fascia, shows continuity on my multimeter.


Once again, thanks in advance for your advice.


dcdjr (DrDan)

97 XK8 Coupe black on black

Pacific Northwest USA

 

XK8 gurus,
I have 2 more questions regarding the driver window:

What is the purpose of these 4 resistors in the driver door switch pack diagram? See red arrow in the attached photo.

Are these resistors located on the switch pack PCB or located somewhere else?

Resistors in switch pack

I got the driver window to work properly- up, down, drop 1/2 inch on door open, rise 1/2 inch on door close.

Update: Now the driver door mirror does not work and passenger window does not work. I will troubleshoot these issues using the methods previously described and give follow up.

Thanks,
DrDan
97 XK8 coupe black on black
Pacific Northwest USA

 

They're 'pull-down' resistors, used so that the switch inputs to the door module aren't floating - i.e. are in a known state: ground (logic 0) in this case. They will be within the switch pack itself, most likely on the pcb.

 

Michaelh & XK8 Gurus,Thanks for the info. I now understand the pull down resistors.

The driver switch pack now controls the driver window properly.


The next issue is why the driver switch pack does not control the passenger window. Pressing the passenger up/down switch on the driver switch pack has no effect on the passenger window. The passenger switch pack makes the passenger window go up and down properly and the window drop on opening door works properly. But the window does not go up when the passenger door is closed.


I suspect the first problem could be caused by failure of the driver door switch pack to communicate with the passenger door control module. My understanding is that this communication happens as follows:

1. At the driver door switch pack, press of passenger up/down switch sends 12v to the driver door control module.

2. Driver door control module then sends signal over the SCP network to the passenger door control module.

3. Then passenger door control module then sends 12v over orange blue (OU) or orange black (OB) wire to the regulator motor to raise or lower the passenger window.



Is this the correct pathway?



Is there any other pathway for signal to get from the driver door switch pack to the passenger door control module?


Do you have any suggestions regarding how to test the SCP network? How can I tell whether the correct SCP signal is arriving at the passenger door control module from the driver door switch pack?


Thanks,

dcdjr (DrDan)

97 XK8 coupe black on black

Pacific Northwest USA

 

Hi Doc,

Posssibly the switch itself not 'talking' to the driver's door module?

I wonder if the car thinks the door is always closed? Does the passenger puddle lamp illuminate when you open the door?

Yes

If you have the 97 Electrical Guide, there is a list of the SCP messages near the end showng sender and recipient(s) for each.

I suspect you'd have other issues if there was a problem with the SCP network. You could try holding the key in the unlock position (clockwise) for a few seconds. That should cause both windows to drop if the comms is all OK.