How does the auto inhibit switch work?

David Lawrence · 3rd March 2019, 07:07

I have an Auto that starts in Drive.

It was thought that the car may have had a manual ecu fitted at some time, but it has been T4’d by Jules who confirmed this is not the case. He has confirmed a correct auto ecu all correctly matched to the car, and suspects the auto inhibit switch may be faulty.

These are quite expensive so i wondered at first if anyone knows how they work, because the display in the message centre correctly shows the status of the gear lever, and knows that it is in Drive, yet still allows the engine to start.

So does the switch have 2 switch outputs in it? Does anyone know how to test one with a multimeter perhaps?

I believe this is the switch in question..

trikey · 3rd March 2019, 08:14

You should be able to see on T4 what gear is selected, back to Jules for a quick plug in I reckon!

David Lawrence · 3rd March 2019, 10:27

Quote:

Originally Posted by trikey

You should be able to see on T4 what gear is selected, back to Jules for a quick plug in I reckon!

It is going back to Jules soon to have the work finished, and i was suggested to obtain a new inhibit switch, but they are around £100 on ebay, and for that money i was hoping to test my switch somehow first to confirm it is faulty.

At the moment when i move the lever through each of the positions, the display on the instrument panel correctly changes to match, and yet the car will still start in all gears.

That is why i thought maybe the switch has more than one output. Maybe it can be cleaned or repaired?

stevestrat · 3rd March 2019, 10:48

I'd PM some of the traders here, I suspect you'll get a switch for considerably less than a hundred quid.

Tracker · 3rd March 2019, 12:29

You may want to do a bit more investigation before forking out for another switch. My ZT 180 Auto suffers the same problem and I thought it must be the switch. Bought another one from a breaker for £70 (!) and had it fitted but it made no difference. OK, the second one might have been faulty, but seemed an unlikely coincidence. My investigations at the time seemed to show that they weren't available new anywhere, so I gave up and just take care about gear position when starting. It is annoying, though, and I'd love someone to be able to isolate exactly where the problem is.

David Lawrence · 3rd March 2019, 14:56

Quote:

Originally Posted by Tracker

You may want to do a bit more investigation before forking out for another switch. My ZT 180 Auto suffers the same problem and I thought it must be the switch. Bought another one from a breaker for £70 (!) and had it fitted but it made no difference. OK, the second one might have been faulty, but seemed an unlikely coincidence. My investigations at the time seemed to show that they weren't available new anywhere, so I gave up and just take care about gear position when starting. It is annoying, though, and I'd love someone to be able to isolate exactly where the problem is.

Exactly my thoughts. Cheapest i found is £49. For that money i want to know its going to fix the problem. I would like to know how it works when it is clearly sending out a signal to the instrument panel correctly. Must be another signal that doesnt show somewhere that does the “inhibit” function.

It would be good to get hold of another one to open up and find out how it works. Maybe mine can be cleaned or repaired somehow.

3rd March 2019, 07:07	#1
David Lawrence This is my second home Rover 75 CDT-2001 Join Date: Jan 2009 Location: Wrexham, North Wales Posts: 3,606 Thanks: 195 Thanked 606 Times in 501 Posts	How does the auto inhibit switch work? I have an Auto that starts in Drive. It was thought that the car may have had a manual ecu fitted at some time, but it has been T4’d by Jules who confirmed this is not the case. He has confirmed a correct auto ecu all correctly matched to the car, and suspects the auto inhibit switch may be faulty. These are quite expensive so i wondered at first if anyone knows how they work, because the display in the message centre correctly shows the status of the gear lever, and knows that it is in Drive, yet still allows the engine to start. So does the switch have 2 switch outputs in it? Does anyone know how to test one with a multimeter perhaps? I believe this is the switch in question..

3rd March 2019, 08:14	#2
trikey Premium Trader Rover 75 Join Date: Nov 2010 Location: Devon Posts: 33,773 Thanks: 8,837 Thanked 14,831 Times in 8,030 Posts	You should be able to see on T4 what gear is selected, back to Jules for a quick plug in I reckon! __________________ Lest we forget..

3rd March 2019, 10:48	#4
stevestrat This is my second home ZT260 #243 (resting) Join Date: May 2010 Location: Prestonpans Posts: 22,485 Thanks: 650 Thanked 4,624 Times in 3,358 Posts	I'd PM some of the traders here, I suspect you'll get a switch for considerably less than a hundred quid. __________________ Steve T4 Location Map

3rd March 2019, 12:29	#5
Tracker Loves to post MG ZT Join Date: Sep 2015 Location: Dunmow Posts: 350 Thanks: 139 Thanked 83 Times in 72 Posts	You may want to do a bit more investigation before forking out for another switch. My ZT 180 Auto suffers the same problem and I thought it must be the switch. Bought another one from a breaker for £70 (!) and had it fitted but it made no difference. OK, the second one might have been faulty, but seemed an unlikely coincidence. My investigations at the time seemed to show that they weren't available new anywhere, so I gave up and just take care about gear position when starting. It is annoying, though, and I'd love someone to be able to isolate exactly where the problem is.