Low voltage across boot solenoid

[avie rose]

Hi there,

On my mk 1 sdi estate, I can't open my boot from the fob or the finger pad above the licence plate, only from the lever by the drivers door.

Last week I changed it the whole latch assembly for a new one, with the solenoid. However it still doesn't work. I've put the multi meter across the pins in the wiring harness that goes into the solenoid and get a reading of about 0.5v for a fraction of a second when pressing the boot release on the fob and the finger pad.

I assume this should be more in the region of 8-12v for the solenoid to fire. If this is the case what could be causing my low voltage?

FYI, I also suspect that the microswitch in the drivers door locking mechanism had failed, could the issues be linked?

[sepulchrave]

Check the wiring in the rubber boot to the tailgate, it sounds as though the solenoid power cable has fractured internally.

[iainfm]

I've got a similar issue on mine, although it doesn't have a remote fob. Happens intermittently, but fairly frequently. The loom was my suspicion as well, but haven't looked at it yet.

 

Check the boot light is going off, as the solenoid won't operate if it thinks it's already open.

 

The main annoyance for me is that the spring/struts aren't strong enough any more to open the boot past the first latch when I pull the lever, so I either need an assistant or have to crawl into the boot and open it manually. 

[avie rose]

The boot light is going off when I close it, but it doesn't always come on straight away, or at all some times.

I'll pop out and have a look at the loom in the rubber housing later today.

Is there any special technique to removing it enough to inspect the wires?

[avie rose]

The main annoyance for me is that the spring/struts aren't strong enough any more to open the boot past the first latch when I pull the lever, so I either need an assistant or have to crawl into the boot and open it manually.

Have you tried tightening the cable from the lever at the latch end. Mine wouldn't always pop first go until it took some slack out of it.

[iainfm]

Have you tried tightening the cable from the lever at the latch end. Mine wouldn't always pop first go until it took some slack out of it.

 

No, not yet. It seems to pop ok, but doesn't lift far enough to clear the second part of the latch. I'll try that though, thanks!

[avie rose]

Yeah, I had that issue as well. As soon as I tightened that cable it opens first time every time now. I think the cable had just stretched enough so that there wasn't enough tension to push the trigger all the way to open the latch.

[avie rose]

I spent a couple of hours with the car and my soldering iron last weekend. I ended up replacing the wire from the c-pillar to the tailgate release motor because I wasn't getting consistent continuity along it. New wire has good continuity now, but the bloody thing still doesn't respond to either the grip handle or the remote fob. Guess my problem is further up the wiring towards the convenience module.

 

First though, I'm going to need to check out the route under the trim around the NS rear door as there appears to be a small portable lake in there which probably isn't helping enormously with the boot release!! 

[avie rose]

Still not resolved this.

Anyone got any wise ideas as to what I can try next?

I have replaced wiring from c-pillar to boot release and tested for both continuity and voltage. Good continuity and the voltage spikes when pressing the release and the button on fob, but the pulse is too quick to get a reading on my multimeter.

There is no sound from the motor at all on either the new one or the old one. I've had the old one apart and tested it on a12v power source and it works, so not a motor fault?

I also tested for continuity across the pins for the release motor and that seems fine.

Scratching my head a little over this one.