One of my customers had to replace a battery. $168 From somewhere. So today I got to detail the car and I decide to see why the dash say the trunk it open. Well, I fold down the seat, close everything up and the trunk light is on.

While in the trunk I notice that there is a plunger about 6 inches to the right of the latch. Is this the switch that will make the light go out and kill the dash warning?

The dealer said the switch is $12 and some change. I'll order it tomorrow. Does anyone know if that switch will fix the light and dash warning? Is that switch easy to get out of the trim or do I need to take some trim down?

Thanks.

 

Oh, she has a 2003 S-Type.

 

Should be plug and play... I know on many other luxury cars (bens, bmw, and everything else I have changed them on in the past) they are very easy just don't break the connector plug when changing

 

Yes - however, before changing that switch - make sure the Rear Body Trim Panel is in place and fastened in properly - that is where the plunger should make contact with when the trunk lid is closed essentially turning the trunk light off and turning off the "boot open" message on the dash.

Part Number XR8037925 (Up to VIN N13088)
XR8043400 (VIN N13089+)

Hope this steers you in the right direction...

 

Thanks. With the trunk open, I push the plunger and nothing happens so I assume the switch is bad. $13 Is not a bad part to throw.

 

Good point - but make sure that panel is there... cause the switch will not work (when trunk lid is closed) if that panel is not present.

 

Ok, I will. Thanks.

 

Ok, changed the switch and the light is still on. Crazy, turned out that the other switch was missing a part, I guess it got knocked off at some point. Anyway, is there a switch or something somewhere that can turn the trunk light on when the trunk is closed? Everything else appears to be in place other than a small wire connection under the panel where the spare tire is, I seen a small wire plug under there that wasn't connected to anything.

 

Sounds like that's the transit isolation circuit. Ignore that one.

 

Ok, is there some other switch that keeps the light on?

 

When you depressed the plunger of the new switch does the trunk light go off?

 

Nope, stays on.

 

Possibly the new switch is no good....

 

Well, I actually tested both switches and they are both good. Push in the plunger and the current is broken. I'm stumped.

 

Test switch off the car.

 

I had this problem. Very confusing, you will find a wiring loom bundle behind the plastic cover for the boot hinge. Somewhere in there - at the top, you will find some broken wires because of the flexing. These cause all sorts of issues like boot light on constantly - making battery flat etc and rear proximity sensors to not work etc etc.

 

I'll check that out next time I get my hands on the car.

 

One error in my last post. The loom is not responsible for the reverse parking aid problem, I got carried away there - that turns out to be the dreaded water in boot problem causing the module bolted in the wheel well to fail. That was caused by a split boot lid rubber making the seal very weak at the bottom corners - took ages to find, just lift all off and rotate the whole deal 180 degrees - solved....

The picture shows the area where the loom really gets flexed by the boot hinge. Eventually the wires fail because of fatigue. Soldered new sections of wire in place - now interior boot lights go off when they should, also means boot release now works again......5 wires were broken, some with the insulation still intact - just pull a little you'll see!

Oh BTW this problem starts with intermittent alarms from the car when parked and locked (because alarm thinks boot has just been broken into as the wire breaks intermittently!!) But I put it down to high temperatures messing with the ultrasound in the cabin......only now do I realise that was connected.

 

I had similar problem with trunk light staying ON. Lately info "TRUNK AJAR" was displayed. Also I had two unexplained sound alarms.
So I changed trunk switch- nothing changed. Also got to clean contacts,...
Anyway finaly I climbed to trunk(had to remove speaker box) and dissected the harness .
Three wires were broken. Rest of 8 wires had some cracks or damage on insulation. Quite a mess. All result of mechanical motion of harness loop.
I soldered the three wires and so far so good.
I am now thinking what to do for long run... change all section of wires to recommended high flexible multistrand wires?
I also noticed temperature from existing incandescent 'Edison's age' bulb.
So I changed to more modern and less power LED type; and added another LED trunk light to driver side ( while soldering iron was hot...).