First of all, thank you to all the knowledgeable people who have helped me over the years, you are great!

My problem is my convertible top has stopped functioning. I have checked everything people have recommended. What should I do next?When I push the top down button, the quarter windows go down, then the side windows drop a little and there is a hum from the back, then the hum stops, but no top movement or latch disengagement. When I push the top up the quarter windows go back up.

1. Checked the fluid level for the convertible top pump, right between the lines.
2. Checked the petcock, all the way clockwise.
3. Remove the battery and had it load tested. Visually check to see that the hold clamp for the battery is not distorted and stressing the battery casing. Done battery OK
4. While the battery is out thoroughly clean the connections, and remove and clean the ground cable to the body. Done
5. Follow the end of the positive cable and make sure the connections are clean and tight. Done
6. Under the bonnet is the connection for the cable from the boot to the engine compartment. Make sure it is clean and tight. Done
7. Did a hard reset of the system by touching the negative cable to the positive lead for 30 seconds Done
8. Removed and cleaned the relays for the top up and top down and reseated them – Still not working.
9. Switched top up and top down relays. Still not working.
10. Checked fuse 1(Window Raise/lower relays), 12 (Right Hand rear quarter window lift motor), 14 (Raise and lower pump for convertible top), and 20 (Left Hand rear quarter window lift motor) and they all look fine.

 

Do you have any kind of pressure-reducing device installed on the pump? These include
- replacement springs for the pump's internal pressure regulating valves,
- an external relief valve,
- a resistor installed in the pump's electrical supply.

 

Yes, I have the Hydraulic Relief Valve Kit from JagRepair.

 

I had to change the fluid in my 1997 XK8 roof to a different type after the roof started doing exactly what yours is doing. Jaguar had used the wrong fluid at the factory and the change has meant the roof has been fine for the last 20 years. It might have only been the very early cars which were filled with the wrong fluid so yours might have the correct stuff from the start.

Richard

 

Over time the latch and top might start requiring a little more pressure to operate. Needing lubrication, for example, You might try lowering the top with the relief valve temporarily removed. If that works, I believe the valve is adjustable for more pressure, but don't know how that's done. Someone here will know.

Edit: Also worth trying ... open the petcock and exercise the latch back and forth using the hex key. This should require firm pressure but nothing crazy. Remember to close the petcock when done.

If this does not work out, another possibility is that the system has gotten "confused" about where it is. There is a reset procedure for this (beyond the battery hard reset). I'll look that up if needed.

 

I changed my fluid in 2015, how frequently should it be changed?

 

Thank you, now it is getting weird.

I followed the guidelines:
1. Lowered the side front windows
2. Pushed the Top Down button, this made the rear quarter windows go down
3. Released the pressure by turning the petcock, saw the level rise between the lines on the tank
4. Opened the latch with the 8 mm wrench
5. Unlocked the Rams and laid the top down
6. Lubricated the Latch
7. Closed the petcock
8. Touched the negative cable to the positive cable for 50 seconds
And now when I pushed the Top Up button, nothing happens, but I can hear the hydraulic pump running.
Any ideas?

 

Once you have the correct fluid in there, I don't think it ever needs changing.

Richard

 

Hydraulics running with no action, unless there’s a fluid leak, sounds like you either forgot to retighten the petcock (easy mistake) or a problem with the solenoids on the motor that switch it between latch mode and top mode. They have tiny fragile wires that break easily. In the US, Top Hydraulics can do a rebuild of the whole pump. Unsure if anyone sells just the solenoids.

 

Thank you to everyone, there has been a delay due to a scheduled trip. But the saga continues, sadly.

I tried to reset the latch in the top of the window and realized the pressure was too great, so I released the petcock in the trunk and was able to release the latch. I then lowered the roof and found out the ram locks had not engaged, so it lowered easily. I closed the petcock.

having reset everything and with the top down, I used the key in the driver door to try and raise the top. It lifted 4 to 6 inches and stopped, even though I could hear the pump running.

Any ideas??

 

The system is just not making enough pressure to raise the top. Possible causes (excluding ones you've described checking):
- Any hydraulic leak, even a minute one. For starters, feel around all of the fittings on the pump for any hint of fluid. (The latch circuit is pressurized while the top is being raised so include latch hose fittings in this.) If all else fails, you might also have to check at the rams and at the latch.
- As suggested earlier, you should try raising the top with the relief valve removed or adjusted to make more pressure.