My tailgate glass wont open on my Touring (Wagon)

[320de46m47]

My tailgate glass wont open on my Touring (Wagon) and I suspect it's because the GMCU isn't coded right.
I don't want to pay 100 euros!!! (yes 20 second job and that's what theyre asking) to get it recoded when I might be wrong!

I know the motor and the lock work as when I bypass the relay it works fine

My question is ..how much current would need to be supplied to the relay trigger terminal if i bypass the gmcu?

it's pin 31 from plug x253 and it's a white and blue wire (RERHS) which goes to pin 4 on the relay. my gmcu is (i believe) not coded to supply an appropriate current so if i can find an alternative (live when the car is unlocked) and use the tailgate window switch to complete the circuit i should be in business



the relay was changed by the way.
current to trigger passes along a 0.5 mm wire so needs to be very small

[bungy42]

Mine doesn't work from the rear window switch (under the rear wiper pivot) but it does work from the key, so I suspect I've got a broken wire between the switch and the motor. But that doesn't help you any.

Most 12V relays are designed to draw some minimal amount of current to close the contacts. The schematic doesn't specify what type of relay is used, so I can't be certain, but less than 100mA usually will do the trick. Let me know how you make out.

[320de46m47]

the relay K90 (in the diagram above) has 4 pins 85 87a 87 and 30 (spst?)

i need to be reminded how to do this as ive not played with these things in years

i need a small current at (pin 4 diagram above )on the relay possibly the same current as that supplied to the boot release switch in the car above the hood release.. this is it

so if i splice into 58G red and gray from the LCM then use this via a relay to go to pin 4 x253 all i then need is a trigger current (operated by grounding with the tailgate button) the trigger current must be available when the ignition is on and would presumably much larger than the output

[320de46m47]

ive superimposed the trunk release switch (above the bonnet release) diagram supplied by a .35mm wire from a grey/red wire from the lcm diagram here and added a relay
the power to pin 4 on the tailgate glass relay is now supplied via the new relay prong 30 from the trunk release switch (small diagram). the relay is triggered by grounding prong 86 courtesy of the original switch supplied by ????? ignition maybe?? at prong 85??

[320de46m47]

the trunk release button supply (red line grey and red wire) is no good it dims the interior lights!

[bungy42]

First of all, you've got it connected wrong. Pin 2 of the trunk lid release switch is the +12V supply for the light in the switch. You'll need to connect to pin 6 instead. But, I would think that you'd have to disconnect the wire from pin 6 first. Otherwise, you'll be opening the tailgate AND the glass at the same time.

[bungy42]

Upon closer inspection, I think your whole schematic was wrong, so I redrew it. I think this is what you're trying to do.

[320de46m47]

i think youre having a laugh

[bungy42]

i think youre having a laugh

Perhaps I just don't fully understand what you're trying to do...

Personally I'd just skip the relay, and connect pin 4 of K90 to pin 6 of the trunk lid release switch under the dash.

[320de46m47]

pin 4 is dead

[320de46m47]

the gmc provides a trigger current

[bungy42]

What do you mean pin 4 is dead? Pin 4 should have 12V on it until you hit the switch. The gmc should simply ground out pin 4 of relay K90 in order to actuate the latch motor. I'd verify that pin 6 of K90 has 12V on it. If you've got 12v on pin 6 and not on pin 4, the relay is dead.