L320 Transmission Fault - Gear Shifter Replacement - P081C-64

[haydent]

Park input circuit - Algorithm based failure - signal plausibility failure (68)

update: swapping the shifter did not fix it... it was just a fuse, read below

Gear display on dash would not stay on D, and flick between D1/D2/D3 (which is weird because you normally never see these numbers) and not change gears properly, showing yellow transmission fault message, so had to get it towed.

Once console removed, and plug to the gear shift pcb disconnected, the gear display showed correctly so its assumed this board that detects magnets has a fault. update: swapping shifter did not fix it :(

Commonly available service manuals are missing the interior body sections so its a bit of guess work and googling.

Tips: (things i learnt the hard way)

- The shifter doesnt have to be removed to get the pcb out, the shifter can be unscrewed and rotated on its side in place while connected to the gbox cable
- If you must remove the shifter, you dont have to remove the cable, from the body/box, the white connector just clips onto a lobe in the shifter, and pops off
- If you must remove the cable, there is 4 bolts that allow you to remove the plate that the shifter screws down too, this gives great access to the cable body seal/plug.
- The metal body that the cable seal/plug connects too is very thin, be careful, clockwise (i think) about 5cm to unclip and lift out.

- Shifter lock can be manually released in the shfiter without power once you have the console out
- You can gain enough access to get the pcb out by just removing the trim around the shifter and you dont have to pull out the whole console (with wood trim) like i did.

I will take some more photos putting it back together.

Shifter part number LR021517, not available new/aftermarket anymore, so I got one off wreck.


Console and shifter removed:
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The shifter PCB visible after plastic cover removed, it detects stick position with magnets:

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The Plate and 4 bolts, that you want to remove if you are removing the cable that goes to the gearbox:

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Seal in place:

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Seal removed, the metal is very thin, i broke one tab, so had to use sika to reseal.

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[haydent]

crap... replaced the shifter and still got the same problem... typically i put everything back before testing :(

[haydent]

ok WTF, i found this random video,Park input sensor circuit Range Rover P081C-64 - YouTube (https://www.youtube.com/watch?v=SW_WiOKodD4) and guess what, it made me notice my interior (side) lights weren't working either ! I had to check my glove box index to get the fuse number F57, and sure enough it was blown ! And guess what ??? I replaced it and the gear shifts ok now, like WTF, I thought the idea of separate fused circuits was so they dont take each other out [bawl]

Ok, It seems the interior light circuit also supplies power to the gear shift pcb !?!? dear me...

https://i.imgur.com/UtIukhg.png







https://i.imgur.com/hHTPyih.png

[DiscoJeffster]

Wow. That’s some lazy electrical wiring there.

I guess it’s a good reason to get back to basics and review the wiring diagrams and do simple testing as checking for power to the module would have become clear. I admit though, I probably would have been under the same assumptions

[haydent]

What gets me is that normally the GAP tool can tell you if something is not getting voltage or there's a short. and like i said there was a difference when the shifter was unplugged, so something was going on. Prob is also when you look at the diagrams youll see that fuse, but you want see all other things on that fuse, also in the glove box it just shows the roof light symbol.

Also it seems like maybe they originally intended the wiring from the fuse just for gear indicatior illumination, but it seems the sensor might be using it too...

[haydent]

Turns out it wasnt the shifter, as after a few weeks the fuse blew again with the new one, and kept blowing when i put a new one in, I was just in the driveway, so hobbled back home.

And started looking through the wiring diagrams, and interconnect locations to work out where i can isolate the roof/illumination circuit.

Turns out there's a handy connector behind the drivers A pillar trim, once that was disconnected the fuse wouldnt blow, and its been like that ever since (about a month ago) when i get to it ill try and work out with wire in the plug it is and where the problem is, maybe when we had the roof lining out to repair the sunroof shade trim a wire got damaged....

Anyway here's some more photos I took putting it all back together so hopefully it help someone see how it all goes together/comes apart:

This center trim can come out by itself, and this is enough to get the shifter out, lift at rear and slide back to release front tabs, just set the shifter in the middle before taking knob off

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Front tabs:
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Where they slot in:
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To remove shifter, just unclip the main cable, no need to remove the cable from the car like i did in my first posts:

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You can also remove the silver trim for a bit more access
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If you need to manually disengage the shift/park lock without the car power, use your finger on these white plastic bits:

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Shifter parts no
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Removing the PCB that senses magnets on the shifter stick position:

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If you want to remove the whole console it lifts up from the rear first, though remove the screws behind the cd player trim/face first

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[Arivv18]

Hi! I know this is old, how did you get the cable back into the gear tower? I cannot reconnect it for the life of me! Thank you!

[haydent]

i recall it has a 'swing arm locking mechanism' make sure this is fully swung back ?