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For those waiting patiently, here is the write-up on the rear window control using the EXISTING ROOF switch.
To raise the rear quarter windows while the top is down, simply quickly press the ROOF UP button. You will hear 'DING' and the windows will rise fully. To lower them quickly press the ROOF DOWN button.
Holding the ROOF UP button will raise the top, and automagically lower the rear quarter windows first to prevent seal damage.
You can do it for $30-$35 worth of parts, essentially 2 time delay relays, 2 standard relays, a diode, and misc. wiring hardware. If you have installed a car radio successfully, you can do this. At first glance it may look complicated, but if you study the document, you will see it is really not bad.
(4-9-2010 UPDATE: Part I and Part II of the write-up each require 4 .250" Quick connect terminals for the standard relay connections (total of 8). This was inadvertently omitted from the parts lists. An assortment of 18-22 ga. (red) and 14-16 ga. (blue) terminals is recommended as size needed depends on the wire gauge you use.)
You do not need to know this to install it, but for those who want to know how it works: The window up function takes advantage of the fact that the convertible raise cycle does not actually start the instant the ROOF up button is pressed, but after a 1-2 second delay. A 4 second time delay relay is set up to trigger on the release of the ROOF UP button and provide a ground to the window up relays just long enough to raise them. To make sure the switch only activates the window when the top is fully down, and never at any other time (idiot-proofing #1) the ground is provided through the relay by a microswtich already in the system that is grounded only when the top is down. The purpose of the standard relay is just to reverse the polarity of the switch from a negative going pulse to a positve going pulse to properly trigger the time delay relay. The purpose of the reverse biased diode is to suppress energy generated by the changing magnetic field of the relay to avoid potential noise introduction to the electronics in the vehicle.
The autodown function activates another 4 second time delay relay whenever the pump main control valve is activated. It turns out the pump main control valve is only activated a couple of seconds or so after starting the roof close cycle, allowing enough time for the rear quarter windows to close before the roof contacts them (idiotproofing #2). The purpose of the standard relay is to reverse the polarity of the main pump control valve drive signal to properly trigger the time delay relay. By wiring the standard relay close to the main pump valve solenoid, it can share the suppression diode already built into that solenoid, eliminating the need for an additional diode.
Hi White XKR - Sorry to ask an obvious question but is this compatible with your Jag Wrangler remote roof kit? I.e. idiot proofing 2, that the rear quarter windows will go down before the roof goes up.
Hi White XKR - Sorry to ask an obvious question but is this compatible with your Jag Wrangler remote roof kit? I.e. idiot proofing 2, that the rear quarter windows will go down before the roof goes up.
Yes...but...
This thread needs to be carefully reviewed. There are two methods discussed here.
1. Reverend Sam proposes using a simple switch to raise and lower the windows and that is what he shows in his video. This IS NOT idiot-proofed and does not lower the rear windows when you raise the top, which could cause damage to the windows or seals unless you always remember to manually lower the rear windows before raising the top.
2. I wrote about adding two timed circuits. One of the circuits labelled 'autodown' in my write-up. This circuit provides the failsafe to lower the rear windows automatically when raising the top. In my opinion, this is a must.
The other circuit I propose lets you use a quick press of the existing roof switch to raise the rear windows with the top down (it already has the capability to lower them). Unfortunately two issues have been uncovered with this method (reduced life of the top switch and on some cars operation that works only for about a minute once the top is lowered). Because of these deficiencies, I no longer recommend implementing this part of the circuit.
What I recommend now is a combination of the two approaches:
-Implement the Rev. Sam wired switch
AND
-Implement the WhiteXKR 'autodown' circuit, but NOT the 'existing roof switch operation of the rear windows' circuit.
Last edited by WhiteXKR; Feb 22, 2015 at 12:02 PM.
Reason: correction
This thread needs to be carefully reviewed. There are two methods discussed here.
1. Reverend Sam proposes using a simple switch to raise and lower the windows and that is what he shows in his video. This IS NOT idiot-proofed and does not lower the rear windows when you raise the top, which could cause damage to the windows or seals unless you always remember to manually lower the rear windows before raising the top.
2. I wrote about adding two timed circuits. One of the circuits labelled 'autodown' in my write-up. This circuit provides the failsafe to lower the rear windows automatically when raising the top. In my opinion, this is a must.
The other circuit I propose lets you use a quick press of the existing roof switch to raise the rear windows with the top down (it already has the capability to lower them). Unfortunately two issues have been uncovered with this method (reduced life of the top switch and on some cars operation that works only for about a minute the top is lowered). Because of these deficiencies, I no longer recommend implementing this part of the circuit.
What I recommend now is a combination of the two approaches:
-Implement the Rev. Sam wired switch
AND
-Implement the WhiteXKR 'autodown' circuit, but NOT the 'existing roof switch operation of the rear windows' circuit.
Thanks whitexkr a concise and detailed response as always. Time to buy some parts.
I have another twist on this topic. I installed the top up and auto-down relays about a year ago. In the last few months I started having issues with the main windows forgetting their range settings - classic symptom of low battery voltage. I changed out the battery but the problem persisted. After a bit of troubleshooting I finally tracked down the issue to the car not fully going to sleep when locked. Instead of dropping back to around 40ma drain after approx 40 mins the current drain stayed at around 400ma.
After a bit of hunting, I discovered that 'roof up' pin on the BPM floats at around 11V when not grounded by the roof up switch. That voltage passes through the relay coil and keeps the voltage of the ignition switched power circuits at 11V even when the key is withdrawn. This is enough (at least on my car) to prevent the car dropping into sleep mode. Before catching up with this thread I decided to add a diode in the position shown in the diagram and that seems to have fixed the problem for me but I realise it's in a different position from that recommended in the more recent posts. I'm no electronics expert so I'd appreciate any comments on my approach.
I'm also curious as to why the life of the switch might be compromised by the up relay mods. Is it just the extra current that flows across the switch due to powering up the relay coil versus just pulling the pin on the BPM to ground or am I missing something?
Oh yeah... I made a video of the process, but in reality the space it too small to show what I was doing (I was working in the "tunnel" under the arm rest). I'm going to summarize everything with some pictures and wiring diagrams so you can see how I did it. I'll see how the video looks, too. If you can't see what I'm doing, then the pics and diagrams will have to suffice.
Hi Sam,
I need some advise please on this... I first installed the antenna switch, all fine PIN #7 grey connector, work fine, BUT then I got confused when I installed the second switch for the rear windows..question is Are You sure it is PIN #11 and PIN #15??? yellow connector? my car is an XKR 2001...AND .. on my PIN #15 I do NOT have a green/black wire, instead here I have a green/orange one??
the black/green wire is on PIN #16 !!! - so therefore I kindly ask You to assist me, it is now connected to PIN #16, but I do NOT dare to touch/test the switch before someone can confirm I put it on the right PIN #.
OR are You 100% sure is on PIN #15 ? - if so, then I move it from #16 and give it a go..
please see detailed picture below, I really hope You can help - much thanks in advance.
Hey Sam!
I need to roll up the rear windows of my 2003 Jaguar XK8 ASAP. Please give me the full instructions on how to do it myself. I will send you the required amount. of money.
I wish I had read your post earlier.!
Thank you.
Da-Tary Egbuke.
What I would be worried about is if you raise the convertible top while the rear windows are already raised. It's not designed to work that way, so let's hope that nobody finds out the hard way that there is a good reason why. I have no intention of modifying my car but if I did, I would design an interlock preventing the top from coming up unless the rear windows were down.
I had not read post #107 but thanks for pointing me in that direction. Heck, I have enough to do without redesigning my car. I hope that anyone who tries this modification is happy with the results.
I had not read post #107 but thanks for pointing me in that direction. Heck, I have enough to do without redesigning my car. I hope that anyone who tries this modification is happy with the results.
Very very 😊 wth the result. Its not that big a mod but in cooler climates its a must or at speed.
I’m trying to fit a switch on the rear quarter windows on my 1999 XK8, and my circuit set up doesn’t look like anything in the Rev Sam’s video.
Yellow connector- green black and green blue circuits
I have the same question. I have an 1999 xk8 and my connectors don’t look anything like Rev Sam’s video. I know the top yellow connector is for the windows and roof because if I disconnect it they do not work. I tried splicing the bottom two cables in that connector and adding the switch but it did not work. Am I missing something?
Originally Posted by DavidYau
Guys,
I’m trying to fit a switch on the rear quarter windows on my 1999 XK8, and my circuit set up doesn’t look like anything in the Rev Sam’s video.
Yellow connector- green black and green blue circuits
Sorry to bring up an old thread, but those of you with the convertible NEED to do the rear window switch modification. It's a completely different car to drive at motorway speeds with the roof dow
Easy to do as well - three position rocker switch discretely fitted somewhere (I put mine in the center console) which toggles the wires at the rear of the same console to earth.
This thread needs to be carefully reviewed. There are two methods discussed here.
1. Reverend Sam proposes using a simple switch to raise and lower the windows and that is what he shows in his video. This IS NOT idiot-proofed and does not lower the rear windows when you raise the top, which could cause damage to the windows or seals unless you always remember to manually lower the rear windows before raising the top.
2. I wrote about adding two timed circuits. One of the circuits labelled 'autodown' in my write-up. This circuit provides the failsafe to lower the rear windows automatically when raising the top. In my opinion, this is a must.
The other circuit I propose lets you use a quick press of the existing roof switch to raise the rear windows with the top down (it already has the capability to lower them). Unfortunately two issues have been uncovered with this method (reduced life of the top switch and on some cars operation that works only for about a minute once the top is lowered). Because of these deficiencies, I no longer recommend implementing this part of the circuit.
What I recommend now is a combination of the two approaches:
-Implement the Rev. Sam wired switch
AND
-Implement the WhiteXKR 'autodown' circuit, but NOT the 'existing roof switch operation of the rear windows' circuit.
Reverend Sam's video is no longer on-line but from the descriptions in this thread I was able to figure it out and put a switch in to raise the quarter windows. As others have observed, very cool and easy to do!
One problem I ran into, which I wanted to share as a heads-up, is that my driver's side quarter window outboard trim piece gets pushed up and falls off if the top is not already in place. I just noticed by chance, could easily have lost or damaged it. I need to figure out a way to semi-permanently fix it in place, maybe a couple of dabs of hot glue will be enough.
I also wired up WhiteXKR's "autodown" circuit, which too is very cool, and not too difficult for an electrical novice
Thanks to all, active and inactive, who contributed to this discussion!
This thread needs to be carefully reviewed. There are two methods discussed here.
1. Reverend Sam proposes using a simple switch to raise and lower the windows and that is what he shows in his video. This IS NOT idiot-proofed and does not lower the rear windows when you raise the top, which could cause damage to the windows or seals unless you always remember to manually lower the rear windows before raising the top.
2. I wrote about adding two timed circuits. One of the circuits labelled 'autodown' in my write-up. This circuit provides the failsafe to lower the rear windows automatically when raising the top. In my opinion, this is a must.
The other circuit I propose lets you use a quick press of the existing roof switch to raise the rear windows with the top down (it already has the capability to lower them). Unfortunately two issues have been uncovered with this method (reduced life of the top switch and on some cars operation that works only for about a minute once the top is lowered). Because of these deficiencies, I no longer recommend implementing this part of the circuit.
What I recommend now is a combination of the two approaches:
-Implement the Rev. Sam wired switch
AND
-Implement the WhiteXKR 'autodown' circuit, but NOT the 'existing roof switch operation of the rear windows' circuit.
Hi WhiteXKR and the Reverend Sam who has returned. I have been running with whitexkrs remote roof lowering and the rear quaterlights through the roof switch. With autodown since you gave this advise.
But recently the autodown on the rear windows has stopped working. I have checked all the wiring and the relays and timers. I also now get intermitant failure on the remote roof.
Im also getting some cases of the locking on the doors playing up.
So my question is, could the rear quarter window and possibly roof issue be caused by a drivers door latch microswitch playing up?
Ta
So my question is
Last edited by smoggyx100; Mar 9, 2026 at 01:14 PM.
