Intermittent Power Hood Problem

[Varptr]

Hi,
I have a 2001 Z3 3.0 which I absolutely love, but it’s at that age when random bits start going wrong.
Today, for the first time, I had a problem closing the hood. It came up about 1/3 of the way then stopped, this is an electrical issue not mechanical. After a while it sank back and I tried again and the same thing happened again. when the fault happens there is no power to the hood pump for opening or closing. It Is now happening randomly at various degrees of opening or closing so I suspect an intermittent fault with the wiring in the hood which gets bent with every operation. Any ideas?
Also, what is the purpose of the micro switch on the front left side of the hood? When does the hood motor ever need to be automatically turned off?
Thanks

 

[AntStark]

The micro switch ensures you have lifted the front of the roof before opening. Likely the wiring from the switch that routes through the hood frame might be failing.

 

[SV8Predator]

Go outside this evening and see if your brake lights are working. If they also seem intermittent, hold your foot on the brake (with the brakes lights showing that they're ON), then try the power hood again.

 

[black fingernail]

Go outside this evening and see if your brake lights are working. If they also seem intermittent, hold your foot on the brake (with the brakes lights showing that they're ON), then try the power hood again.

SWMBO's hood had a similar problem, it was the brake light switch not working properly, changing it is a bit fiddly, but easy if you wedge the pedal down first.
I managed to strip the switch, and make it work again as a stop gap until the new one arrived.

 

[g8jka]

I've got an intermitent problem with the roof opening at present. I assumed the microswitch at fault so cut it off and joined the wires together to rule out the switch but still had the problem. I then disconnected the microswitch connector behind the trim on the passenger seat and bridged the connections with a small piece of wire and connected back together. All works fine with the bridged connector so it looks like a break in the wiring that goes up through the roof frame from connector to microswitch, which I'll replace soon with new wiring and a microswitch.

This is an easy and cheap diagnosis to see if you have a similar break in the wiring. Just find the connector behind the trim on the passenger side (where a hardtop bracket would sit / under a piece of foam block) and bridge the connector, then try the roof. Also as others have said test the brake lights. Either are cheap and pretty easy fixes if one or the other is the problem.

 

[AntStark]

Just find the connector behind the trim on the passenger side (where a hardtop bracket would sit / under a piece of foam block) and bridge the connector, then try the roof.

Do you have a photo of this please @g8jka ? Not quite sure where you mean ..thanks

 

[g8jka]

Do you have a photo of this please @g8jka ? Not quite sure where you mean ..thanks

Copied from another forum.

This is behind the passenger seat, between the roll hoop trim and rear wing. You may need to remove the piece of foam block first that covers it or hardtop bracket if you have these. You should see the cable that comes from the roof frame, wrapped in braided sleeve. Disconnect the clear/white connector and put a wire between the two pins on the connector that comes from the car side and then try to operate the roof. If it works, make sure you still lift the roof upwards at first when opening as it will now work with the roof actually closed and latched up. Any operation with the hood latched may bend the frame as it doesn't see the operation usually made from the microswitch. If it works with a jumper cable between these two pins the problem is likely to be the microswitch or a break in the cable that goes up through the roof frame.