[Jakg]

I'm in the process of fitting a reversing camera to my E91, and I've noticed the boot lights randomly come on while driving.

I'm guessing that either one of the latches (either tailgate or glass) isn't working right, or I've damaged some wiring.

Is there an easy way to diagnose this? I thought I could monitor the status of the microswitches via INPA but while I can see the doors in the FRM module, I can't see the boot?



Any ideas?

[gbalthrop]

Originally Posted by Jakg

I'm in the process of fitting a reversing camera to my E91, [2008 335d E91 I presume ] and I've noticed the boot lights randomly come on while driving. [Intermittent GROUND, perhaps caused by broken insulation on failing wire at Tailgate Hinge Plane (hidden under harness sheath) as explained below]...

Glad to see you have INPA. It's a great diagnostic tool. Unfortunately, in this instance the interior lights in the Cargo Area MAY show you EXACTLY the same thing as the Proper INPA Screen (JBE/JBBF > F5 Status > F5 Contacts/Latches (Kontakte) which is attached below. The screen for Tailgate (Heckklappe) and Tailgate Window (Heckscheibe) Latches is in the JBBF Module group since those two latches are wired to the JBE, and for Cargo Light purposes, the latches provide a ground (in parallel) to the Cargo Light sockets which receive power from Terminal 30G via fuse F77 on 2008 & Later models, per this TIS circuit diagram; Central Locking Drives circuit follows:
https://www.newtis.info/tisv2/a/en/e...ghting/uPrPcOc
https://www.newtis.info/tisv2/a/en/e...tlputs/hasjYCp

So if the Cargo Lights come on (ALL of them together) intermittently while Terminal 30G is active (Ignition on, and for awhile AFTER shutdown), that is almost certainly due to application of ground to X465 as shown in the schematic. ANY grounding of one of the two White/Brown wires would cause the lamps to light. It is conceivable that there is a fault in one of the latches, and if so, the INPA screen, JBBF > F5 Status > F5 Contacts/Latches, attached below, may be of diagnostic help. In that ScreenPrint, Handbrake was ON & Tailgate & Window were closed. I have NO Auxiliary Water Pump or Compressor Clutch.

Since the Latches which provide the "Switched Ground" are on the Tailgate, and the Cargo lights are mounted on the Chassis, on either side of the tailgate opening, the "Switched Ground" signal has to go through that harness sheath and be flexed every time the tailgate is opened or closed. "Therein lies the rub".

Please share any knowledge you gain, particularly related to INPA, from diagnosing this issue. If you DO find wiring damage at the "flex point" in the harness sheath, there are a NUMBER of threads about different repair methods folks have used.

George

[Jakg]

Originally Posted by gbalthrop

Glad to see you have INPA. It's a great diagnostic tool. Unfortunately, in this instance the interior lights in the Cargo Area MAY show you EXACTLY the same thing as the Proper INPA Screen (JBE/JBBF > F5 Status > F5 Contacts/Latches (Kontakte) which is attached below. The screen for Tailgate (Heckklappe) and Tailgate Window (Heckscheibe) Latches is in the JBBF Module group since those two latches are wired to the JBE, and for Cargo Light purposes, the latches provide a ground (in parallel) to the Cargo Light sockets which receive power from Terminal 30G via fuse F77 on 2008 & Later models, per this TIS circuit diagram; Central Locking Drives circuit follows:
https://www.newtis.info/tisv2/a/en/e...ghting/uPrPcOc
https://www.newtis.info/tisv2/a/en/e...tlputs/hasjYCp

So if the Cargo Lights come on (ALL of them together) intermittently while Terminal 30G is active (Ignition on, and for awhile AFTER shutdown), that is almost certainly due to application of ground to X465 as shown in the schematic. ANY grounding of one of the two White/Brown wires would cause the lamps to light. It is conceivable that there is a fault in one of the latches, and if so, the INPA screen, JBBF > F5 Status > F5 Contacts/Latches, attached below, may be of diagnostic help. In that ScreenPrint, Handbrake was ON & Tailgate & Window were closed. I have NO Auxiliary Water Pump or Compressor Clutch.

Since the Latches which provide the "Switched Ground" are on the Tailgate, and the Cargo lights are mounted on the Chassis, on either side of the tailgate opening, the "Switched Ground" signal has to go through that harness sheath and be flexed every time the tailgate is opened or closed. "Therein lies the rub".

Please share any knowledge you gain, particularly related to INPA, from diagnosing this issue. If you DO find wiring damage at the "flex point" in the harness sheath, there are a NUMBER of threads about different repair methods folks have used.

George

Thanks for your reply. My next question was going to be in the absence of any further software help, how do they work so that I can diagnose them myself, and you've covered that off.

Both cargo lights come on simultaneously.

Just to be clear I understand correctly (I'm also writing this to refer back to later when I test it):

The lights and the latch themselves are wired separately - i.e. the lights can be on as if the boot is open, but the car can think the boot is latched.

The fault is going to be on the interior lighting circuit - specifically the White/Brown cables coming from the lights to the latch - this should be grounded only if the latch is open, otherwise not.

If a ground is required to complete the circuit, the wire must be chafing on the body somewhere.
Or, much less likely, it's stripped and is touching an exposed ground.

If I disconnect the ground from inside the body - X465 appears to be used only for the boot lights, tow bar & rear window lock - and jiggle the wires, I should get an intermittent boot light come on. Which I can then test with a multimeter using the above.

[gbalthrop]

Originally Posted by Jakg

... Just to be clear I understand correctly... The lights and the latch themselves are wired separately - i.e. the lights can be on as if the boot is open, but the car can think the boot is latched. ["Sorta" concept is difficult to absorb/ retain. With me it's "now I see it -- now I'm NOT so sure" See Below]
The fault is going to be on the interior lighting circuit - specifically the White/Brown cables coming from the latch - this should be grounded only if the latch is open, otherwise not. [ANYTHING that applies a Ground to X465 with Terminal 30G Active (Ignition ON and briefly after shutdown) will cause Cargo lights to come on. Open Tailgate & Rear Window Latches CAN provide that ground per circuit linked previously, but ANY application of ground can do the same.]...
If I disconnect the ground from inside the body - X465 appears to be used only for the boot lights, tow bar & rear window lock - and jiggle the wires, I should get an intermittent boot light come on. Which I can then test with a multimeter using the above. [Actual extent & routing of wires is PROBABLY more involved than that, due to location of some components on the chassis, & SOME on the Tailgate. Once again I would defer to "Tambo" who has actually taken things apart and traced wires while I have NEVER had to deal with issue -- I simply try to follow wiring diagrams & learn from the efforts of others]

Fellow UK'er, "Tambohamilton" is the current authority on the Latch Circuits on E91's. Here is the thread where the different Latch/Lock Functions are investigated in detail:
https://www.e90post.com/forums/showthread.php?t=1662097

There are several problems in trying to understand EXACTLY how the FOUR different wires of the Tailgate Latch Function. For Starters, there is NO SINGLE wiring schematic which shows ALL FOUR. You have to refer to these four different diagrams:
1) Central Locking Inputs (inputs TO JBE)
2) Central Locking Drives (outputs from JBE)
3) Interior Lights
4) X465 circuit (Ground for Lights & Towing Hitch Release)

Actually, except for trying to understand WHY INPA or your Instrument Cluster does NOT show either the Tailgate or Rear Window to be open, and YET your Cargo Area lights are on, you REALLY don't need anything but the Interior Lights diagram, and perhaps the X465 diagram:
https://www.newtis.info/tisv2/a/en/e...ghting/uPrPcOc
https://www.newtis.info/tisv2/a/en/e91-335d-tou/iXQNh6U

If BOTH lamps, mounted on the chassis on either side of the Tailgate, come on at the SAME time, then X465 has become "Ground" by definition -- the lit LAMPS are your test lights. If NEITHER the Instrument Cluster or INPA JBBF > F5 > F5 Latch screen I posted earlier show an open latch (circle darkened in INPA) then its just a matter of trying to figure out HOW X465 is being "grounded".

I have NOT dissected a Latch, Tailgate or Window, to determine if pins are connected, but it appears to me that the Lamp Ground Pin and the JBE "Input" Pin are SEPARATE. If that is the case, one would NOT expect the Latch circle on Screen F5 Latches to darken when a ground is applied to the White/Brown wire at Pin #1 of X311 at the Tailgate Latch, BUT the Cargo Area Lamps should light (ignition ON).

Obviously, there could be a fault within a latch where the Chassis Ground is being connected to the White/Brown wire (Pin #1 at X311, or Pin #2 at X13059). Depending upon how frequently and under what road conditions the lights intermittently come on, you could always remove either latch from consideration by disconnecting its connector (X311 or X13059) and if the lamps light with connector disconnected, that disconnected latch is "exhonerated" (actually ;-).

If you want the "Total Boggle", here are the TIS circuits for Central Locking Inputs & Drives (Outputs):
https://www.newtis.info/tisv2/a/en/e...inputs/dPBLOhG
https://www.newtis.info/tisv2/a/en/e...tlputs/hasjYCp

Interesting, mind-boggling problem. Hope you find a simple solution & explanation. Please enlighten us either way.

George

[Jakg]

Unhelpful I know but somehow this fixed itself.