Z3 Central locking not operating boot from doors

My Z3 has a strange central locking issue that I need to look in to. When I use the key in either the passenger or drivers door it will operate the central locking for the doors. The boot does not lock or unlock if the key is used from the doors. If I use the key in the boot lid to unlock / lock the boot it also operates the doors. So, if I use the key in the door to unlock the door, both doors unlock but not the boot. If I lock the door from the door, both doors lock but not the boot. If I unlock the boot using the key in the boot, the boot will unlock and both doors will unlock. If I lock the boot from the boot lock, the boot will lock and both doors will lock. So, if I unlock the car from the boot and then lock the car from the doors, the boot will not be locked.

It appears that the signal from the central locking from the doors is not making it to the boot actuator. There is a known issue on the Z3 where the wiring loom that goes from the boot in to the car can sometimes contain broken cables. It could be that there is a broken cable in the loom. You can see examples of broken wires in the photos below (courtesy of @jonco on zroadster.org). Detailed below are the indvidual wires and there function.

As soon as lock down allows I will be out to the car to break open the wiring loom to see if any of my wires are broken and causing my issue. I will update the post with what I find.

I have documented here the details of what each wire is used for is noted below (courtesy of @jonco and @BrianH on zroadster.org)

There are 9 wires in the boot loom. The lock/unlock and switch position functions are controlled via the central ZKE module
The two wires below are part of a common loom that triggers the door actuator/lock.

1.5 BL/GR blue/grey – boot lock motor wire

1.5 WS white – boot lock motor wire

The three wires below are supply wires and lock position wires, the supply is fed from fuse 7 (5amp)

0.35 RT/GN red/green – boot lock switch – supply wire

0.5 WS/BL white/blue – boot lock switch – unlock wire

0.5 WS/GN/GE white/green/yellow – boot lock switch – lock wire

The two wires below are for the third brake light, the fuse for the third brake light is fuse F46 (15A) and controlled via the brake light switch.

0.5 BR brown – 3rd brake light – earth

0.75 BL/RT blue/red – 3rd brake light – supply Wire

The two wires below are for the boot interior light, this switch is located in the boot latch. The fuse for the boot light switch is F33 (10a).

0.5 BR/WS brown/white – boot light switch supply wire

UPDATE: I finally got around to opening up the loom and found that I had a blue wire that was broken. I stripped back the wire and soldered it back together and now the central locking works exactly as it is supposed to.

New Addition E36 Z3 Roadster 1.9

So it has been a busy few weeks here with regards to the cars. At the end of June I traded in the E39 530i Sport touring for the E70 X5 xDriver 40d. We have been so happy with the new X5, it is so comfortable, easy to drive and a great tow car. This left us with two X5 as I still had the E53 x5 3.0 sport. As the E53 was not being used so much since the E70 arrived, the decision was made to sell it on to a new home where it could be appreciated and driven. I had just come back from a few days away with a friend where we went to the Nürburgring and drove around the Nordschleife in a Vauxhall Vivaro van (an ex-AA van at that with a 60mph limiter) and went to the BMW Museum and BMW Werk in Munich.

During the hours of autobahn driving we discussed our cars, my friend having recently purchased a BMW E36 Z3 2.8. The discussions about our next possible trips and how it would be great to go around the Scottish North Coast 500 with the tops down.

As the E70 X5 really doesn’t need any work on it I needed a new project car. The new car would have to be a Z3 project car. The E53 X5 was sold and the money from this sale went to purchasing a cheap Z3 project car that was advertised on a Z3 facebook group.

From first impressions the car doesn’t look that bad. The wheels are non-BMW, a decat exhaust is fitted and the car is lowered by 30mm. It was only under closer inspection that the amount of work needed came to light.

On first impressions the hood looked in good condition, there was some rust in the usual places on the sills and the passengers back wing. There was water in the boot and there some were missing rubbers from around the windows (already sourced and replaced). The door locks will only operate from the central locking from the boot and there is a scuff on the front bumper. Not too much to work on. The car came with the original exhaust and springs so these are the first things to go back on the car once a full service has been completed.

I asked my local garage to do the majority of the work since I currently don’t have access to a garage or somewhere to jack up the car. The garage performed a once over and found the following items: –

  • Boy racer go faster air filter (already got the missing air filter box parts and put back to standard air filter)
  • Thermostat needs replacing (I noticed the temperature not rising during the test drive)
  • Front tyres with no rubber left on them, down to the bare threads underneath. Not an issue as new BMW Z star wheels have already been purchased which have nearly new tyres.
  • Power steering and brake pipes corroded.
  • Broken bolts holding exhaust on to manifold (not an issue as original exhaust going back on the car)
  • Handbrake needs adjusting (getting new brake fitted)
  • water in the boot looks to be coming from the rear light.
  • Digital clock has a couple of segments not working (not the end of the world but will be sourcing a replacement)
  • Gas struts on boot lid broken. Replacements sourced from eBay already.

At the time of writing, the car is in the garage having most of this work completed. New panels have been sourced in the car colour to replaced the panels that have rust, along with some spares for the future. New bumper has been sourced but will first look at repairing the existing bumper as I want to play.

The car has had an initial detailing. I find these really good to do as you get to know the car and find any other items that may have been missed. This highlighted that there is a hole in the carpet on the drivers side. This is hidden by the floor mats but will be replaced at some point. The engine bay has had an initial detail but needs more time. One of the items will be to repaint the BMW logo on the plastic engine cover.

I aim to post some updates on progress as I get through these items. The plan is to have the car in a reasonable shape for the start of the show season for 2020 followed by a week driving the North Coast 500 in September 2020.