E39 touring tailgate catch

[Brianmoooore]

2000 E39 328 touring. For about the last month the glass part of the tailgate has been unlocking itself occasionally while driving along.
I'd just about decided it was an electrical problem, rather than a mechanical problem with the catch itself, but had't got around to looking at it.
Today, however, the thing's gone nuts! The catch release itself a few seconds after shutting it, whether the car is being driven or parked, and if you leave it open, the latch motor operates every 20 seconds or so.
Anyone know if this is a common problem, and can point me in the right direction before I get stuck in? Frayed/fatigued loom in the tailgate hinge?

[DanThe]

First thing id be looking at would be the release button itself

[Brianmoooore]

First thing id be looking at would be the release button itself

It's possible, but it feels and operates completely normally, in the short time before it opens itself. If it was the problem, I'd expect it to be hyper sensitive, or difficult to work at all.
There's a known issue on these with the whole tailgate release button not working (as on Clarkson's E39 on last weeks Top Gear), but that's all working perfectly on mine.

[wellard]

Its more likely to be broken wires in the tailgate hinge, is your radio reception and heated rear window working ok as the wires for the aeriel amp and hrw pass through the same loom?
The rear screen has the pick up for the remote locking as well which passes through the amp and through the same loom.

[Brianmoooore]

All working perfectly again this morning, without me touching anything!! Don't you just love faults that come and go like this!
Radio is and was working perfectly, as is the rear wiper and the main tailgate catch. HRW was working OK the last time I used it, but didn't need or try it yesterday.

[Simon]

I had a problem with my E39 touring where the N/S tail light on the tailgate was flickering, upon inspecting the loom in the hinge quite a few of the wires were wearing thin, ended up repairing about 4 or 5 wires in the end.

[Demlotcrew]

2000 E39 328 touring. For about the last month the glass part of the tailgate has been unlocking itself occasionally while driving along.
I'd just about decided it was an electrical problem, rather than a mechanical problem with the catch itself, but had't got around to looking at it.
Today, however, the thing's gone nuts! The catch release itself a few seconds after shutting it, whether the car is being driven or parked, and if you leave it open, the latch motor operates every 20 seconds or so.
Anyone know if this is a common problem, and can point me in the right direction before I get stuck in? Frayed/fatigued loom in the tailgate hinge?

The rear number plate lights will be letting moisture in, a good dry and coating with oil will stop it happening again.

One way to stop this happening is to lock the car from the inside.

HTH

[AndyG]

its as wellard says, its a common problem on these, had it on mine and was resolved by stripping it back and finding one of the wires earthing itself and unlocking the glass hatch.

[Brianmoooore]

Thanks for all the replies and suggestions, but from the first time I drove the thing after the OP, it hasn't missed a beat! Catch hasn't released itself once, and works perfectly on the button.
Andrew's suggestion concerning the number plate lights is interesting, but I tend to discount it, because it went berserk during the longest dry spell we've had for quite a while.
If it starts happening again, I'll try moving the loom around near the hinge, and see if it affects the problem at all.

[Brianmoooore]

Rear window still behaving itself 100%, but it did put the ABS and ASC warnings lights on for a couple of journeys earlier today, just to show me who's in charge. Been OK for three journeys since!

[Rosc0PColtrane]

Though the moisture could be condensation built up in varying temperatures, or just the culmination of ingress over a longer period of time?

[Demlotcrew]

Generally, abs and acs are the pressure sensors on the master cylinder, £70 from BMW I believe. If it was anything else that failed (such as a sensor) the warning lamps would stay on. A low voltage could also trigger them, but I would expect other issues at the same time, ie no radio etc.