My first time on the forum, though I’ve learned a lot from previous posts. When I first got my XK8, the convertible top worked flawlessly, however, the right rear quarter window would not operate at all, and stayed in the up position as top lowered.. I assumed the regulator cable had broken, and delayed a repair. A couple of weeks later, I went to let the top down, and the quarter window rolled down as it was supposed to, but the top won’t unlock or lower. After the windows roll down, the top circuit chimes, but nothing happens. I tried manually unlocking the latch and then pressing the button, but the top still wouldn’t lower. I swapped the top up and top down relays with no success, and the fuses are all okay. The fluid level in the pump reservoir is just below the lower level line with the top up and lift cylinders full. I’ve read that a sensor won’t let the top lower over 10 MPH, but nothing in the electrical system is labeled, and the location is not in any of the repair manuals. Any ideas?

 

Welcome to the forums Buckshot Cake,

I've moved your question from US Western Region to XK8/XKR forum. Technical questions should be posted in the relevant Model forum. The Region forums are for meetings, shop recommendations or anything geographically specific.

Please follow this link New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum to the New Member Area - Intro a MUST forum and post some information about yourself and your vehicle for all members to see. In return you'll get a proper welcome and some useful advice about posting to the forum.

Graham

 

I had a similar problem with the right rear window. Got stuck in partial down position. Had the regulator replaced, and all seems good. I did not have any problems raising and lowering the top, however.

 

is it possible the petcock was inadvertently opened - thus no pressure to operate up/down sequence?

 

Buckshot Cake,

I had a lot of gremlins in my 99 XK8 convertible top when i first got the car 2 years ago but worked my way through it. You seem to have done some basics. From what you said, I would ask:

1. Here's a snapshot of the workshop manual showing the relevant level marks on the hydraulic pump in the boot.

I presume you can hear the pump working. Are the electrical connectors all okay as they are known to be brittle? Can you physically see the fluid level moving when the pump is operating? Is the petcock valve fully closed/open. Fully 3 1/2 turns anti - clockwise to manually open the latch and lower the hood. Fully clockwise to tighten and use the J-Gate roof button.
Just like any fluids in a car, when was the hydraulic fluid last changed out? Especially in hot desert climates, like here in Bahrain, old fluid can gum up and cause problems.

2. Have you inspected the condition of the hydraulic hoses around the pump? If they're flakey and/or bulging, then there's a potential huge problem if they break open as the system operates at uber high pressures.
3. The operation of the convertible roof is covered in the workshop manual as below.


From what you said, when you first got the car, the rear right quarter window never lowered even when you dropped the roof successfully. That doesn't sound right as the glass would impinge on the top's movement. The rear quarter windows should be tight and shouldn't rattle/wobble/be slack if you try to move them by hand - maybe their regular motor bolts are very loose.
Secondly, my understanding is that the convertible top operations are controlled by BPMs over the CAN-BUS network, so I think, but don't know 100%, the speed limiting roof operations would be driven by the ABS wheel sensors which communicates car speed over the CAN-BUS network. I don't think there's a dedicated speed sensor just for the convertible roof.

Firstly you could have a combination of problems and I would suggest a few simple checks to try and isolate the problem(s).

1. When you have the car in "start zero" condition (ie locked, top up windows up etc), when you get into the car and turn ignition on, if you briefly press the roof switch down, do both rear quarter windows operate? Then hold the roof button up and both of the rear quarter windows should close. Doing that will let us know if there's a problem in the rear quarter windows mechanism.
2. Have you checked all the relays for the roof operations. There are dedicated ones for the quarter windows for the up/down operations. Pic below.


3. When you tried to manually unlock the latch, did it open? The allen key provided sits tight in the hole and, in my first initial experience I needed to give it some muscle (breaker bar) to initially crack it open.
4. As you tried to manually unlock the latch, presuming you opened the latch (sunlight between windscreen and top), the top then wouldn't lower. Did you have the petcock valve, on the pump, fully 3 1/2 turns anti - clockwise to manually open the latch and then push down on the hood linkages at the rear cylinder rams. See excerpt from manual below



I'm trying to isolate what the fault(s) were/was/is. Could be a simple case that the logic is all confused where things are, and a battery hard reset could reset from zero. Could be loose quarter glass window regulators' bolts or could be dodgey relays in the trunk. Is the hydraulic pump working, and are the hydraulic pipes in good condition. The overhead latch is the most difficult to diagnose/fix and many forum members do away with it all together to eliminate the threat of the infamous green shower. Also there are microswitches in the top and bottom of the RHS cylinder ram which let the BPM know the position of the roof.

Try the above and let us know how you get on.

 

We need to know if the pump is running. If it is, we go down one fork in the diagnostic road; if not, the other fork. If it's running you will be able to hear it (with the car's engine off).

 

A request to Buckshot, and to members in general:

If you post a problem here, and people go to the trouble to post suggestions, it would be very helpful to everyone if we could hear back from you. If you found a fix, tell us about it please. If you've put it aside, tell us that as well since sometimes members will check in here if there's an "open case" they think they might help with.

Just my $.02

 

I absolutely agree. In fact I find it annoying. Someone has a problem. Posts up their problem. We suggest. They fix then most don't even bother to say thank you or post again. Not unless they are in trouble that is.

Getting to the stage were I keep promising myself I will not reply to one-post-wonders. Though I do keep giving in just in case its someone genuine that needs help.

 

I'm having a similar problem with my XK8,

When I lowered the top, AOK. When I raised it, the right rear window stuck about half way making crunching noises. I could grab the window and move it a bit up and down.

I tried lowering the top again. The right rear window barely moved while emitting more crunching noises.

Any insight where to start the diagnosis?

Thanks!

 

Crunching noise is from a failed window regulator. They used to come with a new window attached, perhaps you can get just the regulator now.

 

Dontcha just hate it when that happens ?

 

If you are looking to DIY the regulator repair for around $25 look at my working thread here.
Since I posted that I have found the parts are available on Amazon for less than I paid a few years ago.
Plan on taking a whole day to do it your first time. It is a frustrating job.

I would guess a shop will charge you around $1000 to do it due to all the labor hours. Regulator assemblies are several hundred dollars last I checked.

 

I had a similar problem, had to replace the regulator. $900 at my local mech.

 

Thank you all!

Everything you all predicted was spot on.

I, myself, am not a skilled mechanic, but luckily I have one nearby. His Jaguar connection dissuaded him from using the generic electronics.

My mechanic is going to perform the repair on a T&M basis.

I'll post the re$ult...

DrOrb

 

Problem repaired. 865 USD.

DrOrb

 

Dr Orb,

Thanks for following up. Wasn’t cheap and your cost seems to be market rate.

I’m a cheap, zero dollar DIY shade tree mechanic, but sometimes needs must, and car goes off to a professional shop for work.

Most new Jag X100 owners don’t appreciate that you’ll need a fat wallet, or DIY garage skills, to keep our old cars in tip top shape.

Well done!