Gear Shift Locking, Key trapping

Hi All!
I have recently experienced a problem where I could not shift the
gear change out of 'P'. These notes may also help if your key is stuck
in the ignition.

As other helpful souls on this website have pointed out the little red button in front of the gear shift can be pressed to allow the lever to be moved.
I put up with this for a few days before I decided to have a shot at investigating further and hopefully fixing the fault.

I discovered that this fault is with the shift interlock system.
This system ensures that the vehicle is in P (park) before it can be started.
It also requires the brake pedal to be depressed before allowing the shift out of P.
It ensures the shift is left placed in P before allowing the ignition key to be removed.

The three main components of the system are a key lock solenoid at the ignition lock,
a shift lock solenoid at the gear shift and a box of electronics within
the Gear shift housing to control the process.

If you remove the 2 screws either side of the shift housing it can be lifted off.
If you operate the red button you will see the linkage moving that overcomes the shift lock. At the bottom end of the linkage is the shift lock solenoid which would be the normal way of overcoming the shift lock.

If the system where operational, with the ignition on, when you press the brake pedal you would see the shift lock solenoid operating and it would be possible to move the shift out of P.

Mine wasnt!

Another test of the system you might want to do is with the ignition on, operate the shift button on the side of the gear shift handle. You should hear a faint clicking from the
area of the ignition switch. This helps to prove the switch solenoid and wiring.

Mine was clicking.

To the rear of the gear shift mechanisim is the black box of electronics.
This needs to be slid backwards to get it out of it's mounting bracket.
I couldnt do this as the engine bulkhead was in the way.
To overcome this I undid the 4 large bolts holding the gear shift mechanism down
so that I could rock it forward and remove the electronics.

There are 3 connectors to the electronics. A small 2 way connector to the shift lock solenoid (blue wires) and a 3way connector (green wires) to the shift switch.
There is a larger connector that connects the electronics to the ignition switch solenoid as well as providing a supply to the electronics and a signal from the ignition switch.


For further details on Toyota shift lock systems see here:-
http://www.autoshop101.com/forms/h18.pdf

a similar electrical circuit is here:-

http://ww2.justanswer.com/uploads/Hipo64/2011-08-07_181521_untitled.jpg

The electronics box on mine is called 'computer, shift lock control'.
The Toyota part number is 85933 - 26010.
There are 4 clips, 2 either side, that hold the casing of the electronics together.
These can be gently levered with a flat screwdriver to remove the casing and expose the PCB.
Some of the tracks and components on the PCB looked a bit corroded.
I think the likely cause of this is the capacitor C1 mounted at the top edge the PCB
having leaked.
Capacitors contain chemicals and sometimes in old age (25 years in this case!) they can rupture and leak gunge out.

So I replaced the capacitor (220uF 16V). I also replaced the transistor TR1 next to it as the legs were very corroded. The existing transistor is a 2SC2003. I replaced it with a BC337. This need mounting the other way round and the legs crossed. If you google data sheets for the 2 different transistors you will see the different connections. Alternatively send me a message for assistance if required.
So I did all that. plugged it all back into the van and it made no difference!
So I took it out again and gave the PCB tracks a closer look.
Eventually I found a small track on the edge of the PCB leading from TR1 that was open circuit. I repaired this by soldering a link wire over it.
This time it worked! When I put my foot on the brake pedal the shift lock solenoid operates. No more pushing the red button!
In the course of doing this I found that it is possible to drive the van without the electronics in place but you will of course have to make sure you leave the vehicle in P when you switch off to avoid starting in gear.
If anyone needs any help with the electronics just ask. No promises but I will help if I can.
Also, here is a link to a Professor in Thailand who appears to have had exactly the same problem. I used google translate to roughly translate the page but it was the pictures that did most of the talking!

http://netisak.lpru.ac.th/1jz/gear_ecu_2.html

cheers
Mike

Nice contribution for anyone facting these issues in future, thanks.

Mike you are a legend! I can only shift out of Park by pressing the red button which, although not being the end of the world, can be a bit irritating. I will print out your instructions and have a look this weekend as it's been bugging me for ages and an initial investigation didn't throw up anything obvious, this will help loads.

Cheers,

Rich

toldsimply wrote:

 I can only shift out of Park by pressing the red button

I considered this part of the anti theft system.
I had to remove the shift cover to figure out a rattle and adjusted the linkage slightly, no more red button needed.

I found this problem recently and discovered a common or should i say one of the known causes for this safety system failure and its annoying symptom.
If the brake lamp switch fails, it cannot deliver power to the solenoid and release the shift lever. The Lever Lock has an override (red Button) which allows you to manually release the lock.
However! heres the catch as that was not the only symptom, only the one that i found, don't drive around for a week without brake lights. Check your lights and fluids regularly. Happy travels

Thanks Ace MM I'll have a look and see if anythings a bit loose. I took out the black box and a couple of the tracks on the Printed circuit board weren't looking their best. I've currently got that being looked at.

JayDee wrote:

I found this problem recently and discovered a common or should i say one of the known causes for this safety system failure and its annoying symptom.
If the brake lamp switch fails, it cannot deliver power to the solenoid and release the shift lever. The Lever Lock has an override (red Button) which allows you to manually release the lock.
However! heres the catch as that was not the only symptom, only the one that i found, don't drive around for a week without brake lights. Check your lights and fluids regularly. Happy travels

Great addition, this can be useful to others.

So the black box of electronics has been worked on and potentially fixed. The moment of truth will be later tonight when I fit back in the van. Will keep you posted.

Glad I found your post.
I've got exactly the same problem. I have already pulled out that circuit board and replaced that capacitor. I noticed the transistor looked exactly as you described but I didn't have a spare on hand.

Refitted but still doesn't work. I will pull it out again and replace the transistor and check the tracks.

I'll report back when done

Okay, I replaced the transistor and checked all the tracks and solder joints. All looking good.
Refitted but still doesn't work. I wonder if a fuse has blown?
The search for a fix continues...