Can someone please tell me what the Inhibitor switch does and where it is mounted?

The job of the inhibitor switch (also known as the XYZ switch or gear position switch) is to inform the transmission ECU which position the driver has selected with the gear lever. It’s bolted to the RH side of the transmission casing from where the selector shaft protrudes but is hidden behind a protective tin cover.

The starter motor is inhibited from starting the engine if the switch logic says that the gear lever isn’t in either the ‘P’ or ‘N’ positions, hence its name.

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Cheers for that Phil. I'm starting to think this may be my problem. Doesn't start on every key turn and I keep getting the trams safe prog error. Once I'm driving I never get the error. It will only sometimes reappear if I move the gear lever again.

Here’s what’s inside the switch, if it helps :

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That's a brilliant reply Phil, very impressed. Am i right in thinking this error code won't be picked up with the Autologic Diagnostics, only the Landrover T4 one?

I'd be surprised if Autologic couldn't detect the error. In my experience it's just the transfer box shift motor potentiometer issues that Autologic fails to recognise.

Phil

Cheers for your help Phil, hopefully I'll get to the bottom of this, I've certainly got a lot more information now.

Good luck

If you wanted to be doubly sure that your switch was at fault before splashing out on another one you’re welcome to try a spare one that I have lying around (if you’d be prepared to pay the return postage costs). Unfortunately the black plastic cover of this one is broken where the cable enters the switch (exposing the wires to the elements) so it would be too risky to fit as a permanent solution, but it otherwise functions perfectly and would at least allow you to be establish that it definitely fixes the problem so you're sure that money spent on another switch wouldn’t be wasted.

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Phil

I really appreciate that. I'll try and get the diagnostics back on the car and see what errors appear and I'll get back to you.

Hy Paul,

I had this problem on my 02' v8 recently enough.As Phil says get the diagnostic done and look out for the code p0705.

My symptoms were that I was getting Trans Failsafe Prog message as soon as i turned the ignition key to position 2 before I could even start the car.I thought it was the battery initially as it was due a change so I did that and the problem didnt go away.Then to compound the problem when i would turn the key to start I would get nothing but the immobiliser worked fine so I knew it wasnt that and with a brand new battery fitted something was amiss.

All my research led me to the Inhibitor switch and how it works or in my case not works which led to the failure message on the dash and preventing the car from starting as the switch is supposed to tell the ecu whether cars in gear or not.

I got the error code and thats when I changed the Inhibitor switch and all is ok since.

Just adding my tuppence worth,if you havent read RRPhils post on other forums and this,they are worth a read for the enthusiasm,knowledge and great pics on the subject.I dont think anybody knows theses gearboxes any better

Still haven't checked fault codes, but if I put the gear shift into Neutral before starting I do not get the trans Fail safe error. I can then move the shift into drive and no further problems until I put it into Park and then get the fault.

2002 Vogue 2002 Vogue Epsom Green with Ivory Leather.
Discover 2 V8
Discovery 2 TD5
Discovery 1 V8
Audi S4 (2005)
Audi S4 (2000)

thats exactly the same symptoms I had,and thats what I did to drive around the problem for a few days but as soon as I put it in park the message would pop up on the dash

It would seem you have also pinpointed my problem. One thing that noone mentions is the selector lights on the dash don't show which gear you are in. But the ones next to the transmission shifter any gearbox range indicator do show the correct gear. Only when the box is NOT in fail safe mode All the lights function properly Eddie the eagle watch out 👀

Hi, I too have this problem, albeit very intermittently. Does anyone know if the BMW part (part no. 24107512755) will fit as its half the price of the Land Rover part (UHB500020)?

Thanks

Stan uses the inhibitor switch to edit the FFRR posts
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