P38A Electric stuff

1990 4.0 Auto
Tailgate button has not worked for ages and now trying to fix
Trying to test wires and connectors etc but does anyone have a good way of probing these tiny wee connectors in the blocks?
My probes are too big to go into the connector and not sure about sticking a screwdriver in in case it deforms the socket.
Does bare copper wire work without distorting the socket?

I would think that will work ok, if its any help the tailgate earths through the drivers door lock a fault in the lock can stop the tailgate working.

Use safety pins in the back of the connector (or the face, for that matter) - they stick out enough to grab hold of, obviously you have to be a bit careful not to short between two. Also, it's v useful to get a few lengths of wire and put a mix of male or female pins on one end (and whatever you want on the other), so that you can plug them into the connectors directly (if you have the connector undone, and especially if you need to connect to a male connector)

oakey said:

1990 4.0 Auto
Tailgate button has not worked for ages and now trying to fix
Trying to test wires and connectors etc but does anyone have a good way of probing these tiny wee connectors in the blocks?
My probes are too big to go into the connector and not sure about sticking a screwdriver in in case it deforms the socket.
Does bare copper wire work without distorting the socket?

Click to expand...

I think Datatek did a write up on taking the boot button apart years ago. Can you trigger with Nanocom?

As Brian says, it grounds through the centre microswitch on the driver's door lock actuator. If it isn't rust in the switch then that's usually the failure point.

Boot button not working can be one of 3 things, the micro switch in the drivers door lock seems to be the most common, after that the button micro switch fails, I have a low cost replacement for that, and finally the wires can break between the C post and the tailgate.

Thanks for all your replies.
New button and new drivers door lock.
New button only worked for a couple of days then failed again.
Thinking is the earth but having difficulty connecting to the connectors. I am not getting continuity to earth but as they say absence of evidence is not evidence of absence.
I will try a safety pin in the connectors thank you

When mine failed it turned out to be the actuator. Cleaning it and regreasing worked for a few months until it failed again. In the end I just got a newer one off of the Bay of things... I cleaned and grease that one before fitting. Been on for 2ish years, if not longer.

I stripped mine. It’s chrome
(£90 to replace!) Ive thread on it.

Youve had it apart?

If it’s the micro switches I’d go Datas route take it out of the equation.

Its a brand new switch and when pressed I get continuity

The solenoid works by hand and doesnt feel stiff

oakey said:

Its a brand new switch and when pressed I get continuity

Click to expand...

Continuity with a DVM is a bit different to passing enough amps to drive a solenoid. A test lamp is more useful

Good point. Does it not just send a signal to say "I want to open the tailgate" And then the computer stuff says "Ok then" and opens the tailgate?

oakey said:

Good point. Does it not just send a signal to say "I want to open the tailgate" And then the computer stuff says "Ok then" and opens the tailgate?

Click to expand...

Never looked to be honest, I know that the button earths through the door microswitch, I'll have a look in RAVE.

I thought the earth was at C Pillar?

The middle connector does look a bit corroded. Sprayed with contact cleaner and the female bit but not sure if the female bit is clean. And I am talking electrics

oakey said:

I thought the earth was at C Pillar?

Click to expand...

Look at RAVE, the BECM is not involved, the circuit is live via a fuse F15 to the actuator, then to the button and from the button to the micro switch in the drivers door lock, then via the out station to earth.

Aaaah thank you I hadnt realised that. I will check ta

Datatek said:

Look at RAVE, the BECM is not involved, the circuit is live via a fuse F15 to the actuator, then to the button and from the button to the micro switch in the drivers door lock, then via the out station to earth.

Click to expand...

Datatek, could you substitute another earth? Would earthing locally be viable or would that interfere with the driver’s door etc?

oakey said:

The solenoid works by hand and doesnt feel stiff

Click to expand...

Mine didn't, but the motor inside makes contact with the casing, so could be the connection just got weak over time. I was planning on investing further if I could revive it, but never found the time or effort to bother.

Marshall8hp said:

Datatek, could you substitute another earth? Would earthing locally be viable or would that interfere with the driver’s door etc?

Click to expand...

If you substitute another earth, it would be possible to open the boot even when the car is locked.