Electric Hood Issues

Hey all, I have a few problems with the electric hood on the car, and some fault finding tips for common problems would be appreciated. The hood was tried with a knack erred battery a few weeks ago. It struggled to go back, and the then owner helped / pulled it to so it closed. Since then it hasn't worked. Pressing the down button causes a relay to click in and out behind the back seat, but nothing else happens. No effort by pump etc. so, I had bought the only Haynes book that covered the mk1 convertible, but it's a restoration book of sorts with no wiring diagrams to follow. I have been tinkering on my own so I haven't been able to have someone help out while I test various circuits. There is a tension rip in the hood above the relay panel, and this will have let water in over the past, but the hood did work a few weeks ago and it has been out in the elements for months. So, bearing in mind I have no circuit diagrams, can anyone offer ny advice.

see my sig, g1powerhood.pdf

if the guy pulled on the roof without turning the manual hood release valve on the rear motor he may have damaged the lifter units, though even if this was the case the pump would still run i expect.

as you say perhaps a bit of water has got into the electrics, hopefully just a case of buff up some contacts and/or replace the thermofuse(s)

Thanks John. Sorry for the late reply to your advice - had a lot on recently :-( Anyway, pump deffo isnt running when switch operated. One relay clicks but nothing. Thermo fuses seem ok. Took relays out and cleaned all contacts properly and replaced relays. Nada!. Silly question, but is there an interlock to prevent inadvertyent operation like 'switch must be depressed with footbrake / handbrake applied / car in neutral etc.? I think I, going to have to take it to get looked at. :-(

the interlock is from the ignition switch, you need to have the key in but ignition off. perhaps the key-in-ignition live is to blame? its the thin red/brown wire from pin SU. check it goes live when the key is inserted, and trace the wire as best you can

As above, but give the key a wiggle whilst in the barrel.
Like all ready stated you don't need to turn the key, just insert into barrel. You could try swapping a power window switch with the roof switch to rule out the switch it's self.

On later Cabs there is a press stud on the plastic trims near the rear window facing the glass almost. These cut the power to the top when the a tonneau cover is installed.

Check the motor with 12v to make sure that's not Kaput.

if you dont get power to the red/brown you could jump it to the red wire for now, this would mean the roof would work even without the key in but its better than not at all! then get yourself a new ignition switch see if that sorts it. if not its the lock barrel itself which is a bit tricky but we can help you thru that if it does turn out to be the case

Guys, indebted to you for the advice, but to ensure I have properly understood, do you need to have the ignition off, but the key in, for the hood to work or is it irrelevant what position the key is in  / whether the engine is running as long as the key is in?

key in, ignition off

Guys, I feel a complete idiot.

So, this is what happens. I read johns last post. Get home, pull motor out of garage and turn engine off. leave keys in ignition. Undo hood latches. Press hood switch to lower it. Hood lowers. Press switch to raise hood. hood raises. Start car, drive back into garage. Close garage, go into house. Make tea. sit in the garden and think 'you stupid idiot!!!!'


Thanks guys for your help. Its all working and I am releived.

hehe well look at it this way you did a bit of preventative maintenance on the electrics which is always good

Lol it's really common to do that, guess how I know… Lol