I am continuing with the outstanding jobs on my X330 during the slightly eased lockdown. As we all know the wiring to the boot/trunk is subject to repeated flexing and eventually gives way. My car is no exception and the previous owner had been there before me judging by the number of taped joints and bits of wire soldered into the runs. So, I have two problems - first, the release button on the lid does not open the lid, whereas the drivers switch does. The button has two wires purple with green tracer and a black with pink tracer. These feed into a black with pink tracer and a red with green tracer. As far as I can tell I do have continuity from before the hinge area to the joint but very low voltage only. The fuse is OK. Any suggestions? The second issue is the illumination to the luggage compartment. Initially neither lamp illuminated and the fuse was blown. I found a bare wire at the hinge area, taped it up, replaced the fuse and I get the left hand lamp working but not the right. I am getting 12 volts to the left hand lamp, but only 7 to the right hand. The left hand lamp will swap with the other but does not work. the other lamp will work in the left hand spot - thus eliminating the lamps themselves. The good left hand lamp is fed by a brown wire with white tracer and an orange wire with purple tracer. The dodgy lamp has the similar coloured wires. However, there are thirteen wires in the loom at the hinge, of which there are two orange with purple tracer but only one brown with white tracer. To give a fuller picture the thirteen wires in the loom at the hinge are as follows 1 x yellow with orange tracer, 1 x red with green, 1 x purple with white, 1 x red with white, 1 x red with orange, 1 x brown with white, 2 x orange with blue, 2 x lack with pink and 3 black. I hope this inspires you auto-electricians! It just confuses the hell out of me. Keep safe and well during the pandemic and the protests/riots over race. Alec G.

 

Firstly the Boot push button. Have you checked the button is actually working? It is a known weak point.

The button just covers a simple momentary on/off microswitch. Connect your multimeter across the terminals for the switch, or the wires as close as you can get to measure resistance. Press the button. You should get close to 0 ohms. If not suspect a broken switch. The micro switch is easily replaced and is covered in other threads. Like this one
https://www.jaguarforums.com/forum/x...orking-228942/



Secondly the Boot Lamps. There are 3 wires that power the lamps. There is a +ve supply that is shared by the lamps. This is the Brown/White wire (hence only 1 Brown/White at the hinge).

There is then a switched ground to each lamp. Orange Purple to RH Lamp, Orange/Blue to LH lamp. These come from the BPM. Check resistance to ground for the Orange/Blue and Orange/Purple. Should be 0 ohms.

Then check the Brown/White voltage at each lamp to a good ground (like the battery -ve). If it's good on one lamp but not the other, then look for where the cable splits to go to each lamp (could be at one of the lamps?)

Repeat the tests at the cables at the hinge and see if you get better results.

This will identify a faulty cable if there is one. And you can then search further when you know what you are looking for.

 

Thank you B, I have acquired a replacement boot switch as I thought that may be the cause of that problem. Sadly, it has different connectors to mine, I suspect it comes from a later vehicle, and I need to do surgery to make them compatible. As for the lamps, there has been wires let in and it may be that I will have to re-appraise them. Cheers. Alec G.

 

Like b1mcp, the trunk switch is just a momentary on/off. When pressed it just grounds the circuit for the SLCM and then the module knows to pop the trunk. It's not necessary to retrofit a switch to test the circuit. You you disconnect the switch and TEMPORARILY ground the Red Green wire to tell the SLCM to open the trunk. Then once you test that, you can temporarily jump the Red Green wire on the fascia switch connector to the Black wire on the connector and if that pops the trunk too then you know the build in ground circuit also is good. If the first doesn't work, then you know it's possible the signal wire to the SLCM is bad (Red Green). If the first works and the second doesn't, then you know you probably have a bad ground circuit. If they both work, then you probably have a bad switch. If neither work, could be a bunch of things.

Also note, I think the fascia release switch passes through the large connector in the trunk under the parcel shelf, make sure that hasn't wiggled loose.

It's important to test circuits while they are under load. This was actually a perfect example because you found one bulb socket had 12V and one had 7V. But when you put a bulb in the second socket, the bulb wasn't half lit, shouldn't it be? When the circuit is under load, I bet the voltage across the bulb is way lower. It could be partially damaged circuit. Last time I saw that happen, it turned out to be a half split wire, which meant I DID have some voltage at the socket, but it was so weak that when the bulb was in, the voltage disappeared (AKA consumed by the bad circuit instead of the bulb). This is why technicians back probe connectors with pins while the circuits are still on to test the true voltage okay that's enough yapping about that.

I'm talkative about this because I too am in the middle of diagnosing my trunk release circuit, which has turned into diagnosing the entire SLCM circuitry. Not only did I find damaged wires at the trunk hinge, but I found them further up to (don't know how/why!). I personally recommending cutting out the bad circuits and soldering them back together with heat shrink tubing to assure you do not have internally damaged wires. If you don't have time for this, I'd take the electrical tape off and reinspect the wire to make sure there are no broken metal strands within it.

Just a note for other people trying to diag. these circuits. This confirmed by suspicion that there is a typo in the wiring diagrams. The Jaguar electrical diagram shows the "Fascia Trunk Release" switch wires to be PG (Purple Green), and the front "Trunk Release" wires to be RG (Red Green). But in reality the fascia release wires are only PG on the switch pigtail, then they change to RG for the body circuit. The front trunk release switch is PG the whole way. The electrical diagram has the circuit names swapped, plus it doesn't include the fact that the fascia release switch changes from PG to RG.

 

I can confirm that the trunk push button has failed. I tried to dismantle it but it is, of course corroded. I have sprayed it and will have another go. The fasteners are strange having a very, very coarse spiral along the length. The nut seems peculiar too!
So to the luggage lamps. Doing Brendan’s test, I find that the orange/blue goes to the RH lamp. There is no continuity in the wire. I checked in two places - one after the hinge and one before the hinge. This says I have a problem somewhere between the hinge and BPM. I remade some of the dodgy old soldered joints at the hinge, but that has not helped. Could I piggyback the good orange/purple wire and use it for both lamps?

 

That should be fine. Small lamps (I'm guessing about 5w) so should pull less than 0.5 amp each.

 

I have temporarily piggy backed the OK wire for the LH lamp to feed the RH lamp. It works fine. If I fail to get any complications over the next few days, I will solder in a permanent line. As for the push button, After spraying the fastener, I attempted a removal. I snapped the bolt type fastener on one and mangled the flimsy pressed steel nut on the other. Not good. It looks as if the whole Chromium plated boot/trunk module has to be removed to get the push button off. I'll give that a miss 'cos I can see yet more damage happening.

 

I thought it wise to report back that I did encounter further problems with the boot/trunk lamps. After three days, the battery was completely flat! I replaced the battery and the same thing happened to that battery. I then undid my temporary fix and after a further week, no issue has been found. I cannot explain this! I am now looking for a new boot lid harness. Does anyone have the part number, please?