I've been trying to fix my tailgate lock for a number of weeks, and I'm now totally confused !
Maybe a couple of times late last year, it wouldn't unlock straight away, but then by pushing the door down into the latch slightly, it would eventually give in and work. I then had a flat battery before Xmas, as I hadn't used the van for a while so I trickle charged it, and everything seem to be OK, well apart from one thing!
The tailgate won't unlock from the outside at all
- I have managed to get it open from the inside and have been through the wiring I can see and the logic of what's going on, but it's got me stuck for ideas on what to do next.
1. The latch electrics all seem to be working, open / closed / latched all shows up on the MFD. I also bought a new latch, same behavior on the MFD,
2. The external tailgate switch seems to be working. I can hear the micro switch open and close. I have another switch on the way, but I can also short across the plug and get the same behavior.
3. I have tested the existing actuator on the bench and that works, also bought a new one from VW before I figured out I had a 12V source.
4. I get good continuity to earth, from the earth side of the actuator plug.
5. I've done the BCM reset by disconnecting the battery.
If I put a meter across the actuator plug, then I can see a steady 4.8V - which I believe is the BCM monitoring.
If I then squeeze the external tailgate switch, there's a pulse of 11.8 V which I believe 'should' operate the actuator and open the lock. The latch itself has to be set 'closed' to get the 11.8V pulse, if it's in the open state, no pulse. On the bench the actuator only needs a short dab of 12V to operate, which would release the latch then go back to it's 'ready' state. I don't understand why the 11.8V isn't moving the actuator.
This all seems to stack up with how I think it works, i.e.
if the door latch is shut AND the handle is squeezed, then BCM sends the 12 Volt pulse
if the door latch is open AND the handle is squeezed, then BCM just keeps monitoring with 5V
The only errors that I get are an intermittent open circuit, on the tailgate, which I assume is me unplugging the actuator. If I plug it all up, clear the fault and don't touch the wires then I don't get any faults if I try the external handle. The BCM seems to be operating correctly, all the components seem to test out OK - but the flippin' tailgate isn't budging.
Not really sure where I can go next ?
I've search all the forums and not found anything like this, all the VAG tailgate faults are either one of: tailgate switch, the latch or the actuator. No one seems to have a fault where all of these seem to be working, yet the tailgate's not working.
Any thoughts ?
I'm loathed to give in and give it to a dealer, as they will also be starting from scratch, and I can see the meter running up a big bill (and maybe not even get it fixed) !
Maybe a couple of times late last year, it wouldn't unlock straight away, but then by pushing the door down into the latch slightly, it would eventually give in and work. I then had a flat battery before Xmas, as I hadn't used the van for a while so I trickle charged it, and everything seem to be OK, well apart from one thing!
The tailgate won't unlock from the outside at all
- I have managed to get it open from the inside and have been through the wiring I can see and the logic of what's going on, but it's got me stuck for ideas on what to do next.1. The latch electrics all seem to be working, open / closed / latched all shows up on the MFD. I also bought a new latch, same behavior on the MFD,
2. The external tailgate switch seems to be working. I can hear the micro switch open and close. I have another switch on the way, but I can also short across the plug and get the same behavior.
3. I have tested the existing actuator on the bench and that works, also bought a new one from VW before I figured out I had a 12V source.
4. I get good continuity to earth, from the earth side of the actuator plug.
5. I've done the BCM reset by disconnecting the battery.
If I put a meter across the actuator plug, then I can see a steady 4.8V - which I believe is the BCM monitoring.
If I then squeeze the external tailgate switch, there's a pulse of 11.8 V which I believe 'should' operate the actuator and open the lock. The latch itself has to be set 'closed' to get the 11.8V pulse, if it's in the open state, no pulse. On the bench the actuator only needs a short dab of 12V to operate, which would release the latch then go back to it's 'ready' state. I don't understand why the 11.8V isn't moving the actuator.
This all seems to stack up with how I think it works, i.e.
if the door latch is shut AND the handle is squeezed, then BCM sends the 12 Volt pulse
if the door latch is open AND the handle is squeezed, then BCM just keeps monitoring with 5V
The only errors that I get are an intermittent open circuit, on the tailgate, which I assume is me unplugging the actuator. If I plug it all up, clear the fault and don't touch the wires then I don't get any faults if I try the external handle. The BCM seems to be operating correctly, all the components seem to test out OK - but the flippin' tailgate isn't budging.
Not really sure where I can go next ?
I've search all the forums and not found anything like this, all the VAG tailgate faults are either one of: tailgate switch, the latch or the actuator. No one seems to have a fault where all of these seem to be working, yet the tailgate's not working.
Any thoughts ?
I'm loathed to give in and give it to a dealer, as they will also be starting from scratch, and I can see the meter running up a big bill (and maybe not even get it fixed) !
