Hello there New to the forum. Had my 89 xjs conv for about 4 years now, and when getting back on the road this spring, my top doesn't work at all. no clicks or hums from the control box at all. I spent my career fixing medical electronics, so I know my way around a circuit. i can raise and lower the rear windows and top by jumpering out the relays, and all the gnd inputs from the park brake, neutral switch, and top control switch are there. seems like the ECU itself is bad. anyone else had this problem, and if so , is there a fix besides replacing the ECU, if I can find a functioning one at a reasonable price. Thanks Rodger

 

Rodger,

That would be extremely unusual for the hood ecu to fail. I've never heard of one fail. How did you check the signals from the handbrake and selector rotary switch?

You may be right in your assumption that it's the ecu, but it's far more likely to be the hood switch, or the input conditions from the handbrake or rotary switch.

I would start by bypassing the handbrake and rotary selector terminals on the ecu, then remove the skislope and check the continuity from the hood switch to the ecu.

Good luck

Paul

 

Did you check to see if the switch has gone bad? You can swap it with the window switches to see if it is the switch, or something more.