12h-t won’t turn off (1 Viewer)

[kevin in okinawa]

Turn key off, truck still runs. Manually force the plunger thing on IP then it stops, but dash lights stay on even with key removed. Disconnected the negative battery terminal, all power off.

I searched, no luck. What should I be testing? Thanks for your insight in advance!

 

[cruiserpilot]

Look up VSV - vacuum servo valve. It controls the vacuum that shuts your truck off. It’s the little
thing with the round black end/ blue body on it. It will be located on the back of or around the throttle crossover
tube. Mine is bolted there since I did the intercooler mod. It has two little wires powering it. Check
no broken wires. Check vacuum lines are all connected. The VSV is simple, removes easy and
can be inspected in a few seconds.
Did you do anything to the engine lately? Usually something fails cause of something you just did,
by accident or however.

 

[kevin in okinawa]

Look up VSV - vacuum servo valve. It controls the vacuum that shuts your truck off. It’s the little
thing with the round black end/ blue body on it. It will be located on the back of or around the throttle crossover
tube. Mine is bolted there since I did the intercooler mod. It has two little wires powering it. Check
no broken wires. Check vacuum lines are all connected. The VSV is simple, removes easy and
can be inspected in a few seconds.
Did you do anything to the engine lately? Usually something fails cause of something you just did,
by accident or however.
View attachment 2870567

Roger wilco! And thanks for the reply .

 

[David*BJ70]

Not « necessarily » related but worth to share --> my 12HT don’t shut off when I start it just to move it in my driveway.

Not enough vacuum is built to activate the diaphragm. When it happen, I just rev the RPM a bit and it shut off while vacuum is builted.

It happen only when I do not drive my LC for few day. I may have a tiny tiny vacuum leak somewhere. That does not bother me. I live well with this.

 

[kevin in okinawa]

FYI anyone that is looking at this thread years from now, the 24v vsv part number is 90910-12013. amayama has in stock, partsouq did not.

 

[relaxedcruiser]

Hi Kevin,
it's all right what cruiserpilot and David are saying, but you mentioned that your dash lights are still on after you switch off and remove the key. If it is like this then the VSV can't know that you are trying to turn your engine off.
It seems to me that it is more of a problem of the main ignition barrel switch.

 

[Defterdar]

you mentioned that your dash lights are still on after you switch off and remove the key. If it is like this then the VSV can't know that you are trying to turn your engine off.
It seems to me that it is more of a problem of the main ignition barrel switch.

I would agree with this. Sounds like an ignition barrel switch gone bad.

 

[kevin in okinawa]

Hi Kevin,
it's all right what cruiserpilot and David are saying, but you mentioned that your dash lights are still on after you switch off and remove the key. If it is like this then the VSV can't know that you are trying to turn your engine off.
It seems to me that it is more of a problem of the main ignition barrel switch.

THANKS for the reply! this is new information that I have no idea about. Can you share anything about the "ignition barrel switch?" How can it be tested, where is it, any tips for removal/replacement, that kind of stuff? I'm searching, but parts diagrams don't tell me the really good tips that come from ih8mud guys

I did replace the VSV 2 years ago and thought maybe because it was a Chinese part it had failed early.

 

[kevin in okinawa]

I would agree with this. Sounds like an ignition barrel switch gone bad.

THANKS for the reply! this is new information that I have no idea about. Can you share anything about the "ignition barrel switch?" How can it be tested, where is it, any tips for removal/replacement, that kind of stuff? I'm searching, but parts diagrams don't tell me the really good tips that come from ih8mud guys

I did replace the VSV 2 years ago and thought maybe because it was a Chinese part it had failed early.

 

[Defterdar]

THANKS for the reply! this is new information that I have no idea about. Can you share anything about the "ignition barrel switch?" How can it be tested, where is it, any tips for removal/replacement, that kind of stuff? I'm searching, but parts diagrams don't tell me the really good tips that come from ih8mud guys

I did replace the VSV 2 years ago and thought maybe because it was a Chinese part it had failed early.

Try this

Ignition switch replacement procedure.

I've searched, I've searched, I've searched...... Seriously though I've read through a few dozen threads and can't seem to find some info on how the ignition switch comes out and is replaced. No, I haven't started digging into it yet as I prefer to search and do as much research as possible...

forum.ih8mud.com

 

[kevin in okinawa]

contacted amayama for the ignition switch, looks like they probably have it. Before I heard back from them though, I had reached out to ToyotaMatt at VintageTeqParts.com Home Page – VintageTEqParts.com - https://vintageteqparts.com/ and lo and behold he had one on the shelf! You owe it to yourself to follow the link to his website and gander at all the f***ing cool land cruiser parts he has. A lot. A lot of electrical connections. Just go look so you can then make a bookmark of the webpage. Good stuff.

 

[relaxedcruiser]

Thats good to hear, don't want to discourage you but to tackle your problem you must at first check where the culprit is.
There are plenty of electrical circuits in our trucks - but there are three really important ones.
1. Permanent Positive
2. Switched Positive
3. Ground

It seems that your switched positive is live even when the ignition key and as such the switch behind it is off.

This may be because your ignition switch is not working correctly - but it can also happen that permanent positive is feeded into your switched positive circuit at any point where those two circuits are physically close together - being it inside the cable loom or inside a electrical component.
At first I would try to isolate the ignition switch by disconnecting it from the cable loom. If your dash lights are off then - good - you have isolated the problem. Then take the electrical part of the ignition barrel off and try to turn the switch - It migt be that the switch is actually good but the key is not turning it far enough to switch the switched circuit off.
Dig yourself into it - it's actually not so difficult if you strictly follow the procedure of isolating until you find the issue. Its great if you have an permanent issue - which you are ably to isolate. Right now I have the problem that my indicators are not working sometimes - but always when I'm at home - that's not so easy to isolate and difficult to find.

 

[kevin in okinawa]

Isolated isolated both the ignition switch and the VSV, no luck same problems with lights staying on the dash with key out. After pulling fuses, the 15 amp engine fuse when pulled makes all the dash lights go out. Any ideas which relay or whatever?

I will continue to research

 

[kevin in okinawa]

 

[kevin in okinawa]

I'm ordering 90987-02005 24v ignition relay. From reading today, it's the only thing I can think of that might be bad but I'm not a whiz with this system. The diagrams online on partsouq and amayama are pretty good. Any insight about the 15amp ENGINE fuse and what else I can check/replace is appreciated.

 

[relaxedcruiser]

The circuit where the "15 A engine" is part of might be the foulty one or you just opened that circuit as you would do with a switch. Have you isolated that ignition relais and it had the same effect like pulling the fuse ? Can you still measure 12/24 volt at the terminals of the fuse with the ignition turned off ?

 

[kevin in okinawa]

The circuit where the "15 A engine" is part of might be the foulty one or you just opened that circuit as you would do with a switch. Have you isolated that ignition relais and it had the same effect like pulling the fuse ? Can you still measure 12/24 volt at the terminals of the fuse with the ignition turned off ?

i did pull the relay (02005) and the dash lights went off. I just don't know if that would have happened anyway. Could the ignition relay be stuck in the "open" position? Thereby it starts, runs, fine but just won't turn/shut off?

 

[relaxedcruiser]

Difficult to troubleshoot from a distance - yes the relais could be permanent on. Does the relais "click" while playing with the fuse (on/off) when you touch it simultaneously with your finger ? If it's stuck it's probably not clicking any more. If it's clicking you need to check why it's clicking or working while the key is in off position.
Get a good circuit plan of your system - I believe you'll find it online-and study it. If the relais you are talking about is the very one which is responsible for switching the power on and off in your circuit, then you should check the energizing circuit of it while its pulled. Does that relais actually gets current/power while the key is in off position ?
There are so many possibilities here - you need to read the circuit plan and understand what's going on - measure accordingly - and sytematically encircle the problem, narrow it down until you find the issue. Like you did with the main ignition switch.
Sorry, I could dig in it too now but it's also bed time over here...... good luck for your next measurements !

 

[ibinazbass]

@kevin in okinawa do you own a multi meter?

 

[kevin in okinawa]

@kevin in okinawa do you own a multi meter?

yes I do, and one of those things that light up/probe also, lol. What can I test?