Hi

I apologise for this thread but I've been searching and still not been able to fix the problem.

Like with other people I can open the boot with the key but not with the fob or the button inside the car.

When I press the button inside the car I can hear a clicking noise.

I've already tried another boot lock and it still doesn't work.

Is there anything I can do to check the wiring?

One again I apologise for the repeated question.

Check the wires in the rubber conduit between the roof and hatch.

The MK1 has a common problem where the iring insulation gets brittle and snaps the core.

I found this problem on my old MK1 and loads of wires went resulting in the boot popping every time aI applied the brakes (shorting from 3rd brake light feed to the lock feed).

I also lost the rear wiper, demister feed and had to replace the boot lock as the lock solenoid fried.

OK thanks I'll try that tonight. Really appreciate your help.

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I do my best ;)

Hi

I've check inside the conduit and it send to look OK. The rear wiper works and so does the water jet, can't check the rear demister but the light comes on.

I've tried metering the pins and I get a few different readings, most notably that when you press the button on the dash on one pin out combination the meter zeros out and when you release it you get a reading again.

I've ordered another lock again, maybe the first one was faulty?

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Did you replace the lock barrel with your original one or use a different key?

I do have a guide for swapping barrels over under my posts if need be.

I just plugged it in to test before carving up the barrel. The new replacement should be here in the next couple of days, really hope it works.

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Hi again.

The replacement lock came and it still doesn't work. There's definitely 12v going to the lock and when I press the button one of the pin outs zeros out.

The wiper, washers and plate lights work is there any thing else I can try?

Thanks again

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Hi

Here's the meter readings.

1 Switch

2 N/A

3 GND

4 12.91v

5 Vanity Light

When Button Pressed

1+3 Spike 12.91v then drops to 0v

4+5 drops from 12.11v to 12v then goes back to 12.11v

Thanks

Hi

I've connected the lock to a bench PSU and tested it and it works fine.

So the problem must be the wiring.

Is it possible to have 12v to the lock and have no current?

Thanks

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Have you checked the earth?

Hi

I've run another ground wire to the gnd pin on the plug and I've also spliced in another plug I got with her new lock to a new ground and the same switch wire further up the cable.

I've just tried metering the lock whilst its plugged in and when I press the button the voltage doesn't change like it does when it's unplugged.

Thanks again

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Switch faulty then?

The boot release on the dash? Would that stop the button on the fob working too?

Or did you mean something else?

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Yes, dash one.

Try a test at that end.

What sort of test should I try, what am I looking for in particular?

Because it does look like the switch is working, as I can detect the voltage change at the lock, but it's like there no current to actually drive it.

Thanks again!

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The lock functions are driven by the Generic Electronic Module which takes signals from the fob and the cabin switch. As the fault is common to both it must lie within the GEM or the wiring from it to the tailgate. The scenario you describe suggests that the drive voltage to the lock motor collapses as soon as it's put under load. This means there is a high resistance somewhere in the circuit. It could be a duff solder joint in the GEM or a corroded connector pin.

Hi mjt thanks for you reply.

Do you know if I can just swap the GEM or does a replacement require programming?

Thanks

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According to my Haynes, which is admittedly for a Mk1.5, the vehicle and security settings have to be read off the old one and programmed into the new one.

Before swapping it would be worth inspecting the connector on the GEM and maybe continuity checking the lock motor wiring. You mentioned earlier that you'd tested a lock motor on a bench PSU so perhaps you could try applying 12V to the appropriate wire with the connector unplugged from the GEM.

Hi again

Really appreciate you taking the time to reply.

I've located the GEM in the divers foot well and removed the connector block. I've visually checked the pins inside and they look clean. Is it possible to look inside the GEM to get a better picture or is out a sealed unit?

When you say continuity check the motor wiring, where should I be looking for continuity? What should I be metering.?

I'll try giving the 32AA-27 wire 12v and see if it rivets the boot lock motor. If it dues I guess the wiring is OK.

Thanks again!

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I've never examined a GEM so I don't know if you can get inside. Maybe one of the more knowledgeable folk on here can answer that one.

As for continuity what I meant was that if you've identified the wire that goes from the GEM to the lock motor you could check its resistance. One way would be to short it to earth at one end and then measure between the other end and earth. Alternatively measure the resistance of the lock motor and see if you get the same reading measuring at the GEM end connector pin.

Yes, if pulsing the wire with 12V operates the motor the wire is ok.

I've just had another thought though - maybe the voltage is not collapsing under load. You mentioned you saw a voltage spike at the motor. A short pulse is all you would expect when the motor operates. The circuit in the Haynes shows two sets of switch contacts in the lock motor assembly and these are likely to be providing feedback to the GEM so it knows when the motor has moved the required amount and needs to cut off the current. Is it possible the motor is actually working but the motion is not being transmitted to the lock mechanism?

Hi

When I had it on the bench and applied a 12v feed to the lock it opened.

When the cable is unplugged from the lock and you press either the fob or the button inside the car I can read 12v.

When the cable is connected to the lock you read 0v with our without the button.

I've connected a second connector and run it with a new earth and spliced into the switch wire further up the cable so it's only running on two wires and it still didn't fire.

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Hi again

Not sure but think the second switch is for the light in the boot which I don't have :-)

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On the Mk1.5 circuit both switches just feed straight back to the GEM. The GEM drives the lock and operates the boot light if fitted. I would imagine this will be the same on your Mk1. If the switch signals are not getting to the GEM it will prevent normal operation so it would be worth checking those circuits in addition to the lock motor itself. However from what you've described it does sound like the voltage is collapsing under load and if the wire checks out ok you may need to try replacing the GEM.

Hi again

Just wanted to say thanks to you both for your input.

Boot is finally working, it was the GEM module.

Got one off eBay for £15 and got it reprogrammed at a local garage for £100.

Thanks again

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