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The mkiv Supra Owners Club

Auto gearbox in a manual shell


Homer

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can definately confirm the parking brake isn't hooked up to anything on the trans, my girlfried drove hers for about 100 miles with it on and wondered why it wouldn't hold the car anymore:blink: Both those plugs to the shifter have to be connected for the transmission to work. I didn't know there were different plugs either.

Post a pic up and I'll see if i have the plug on an arristo loom I have been stripping for connectors, you can have it for postage only.

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In the mean time, I'll try and be a bit clearer about the shifter plugs.

 

The shifter itself is from a UK spec

The interior loom is from a VVTI 6spd - which I believe still has the auto shifter connectors next to the shifter socket, they are simply left blanked off (this was the case in all Supra's I've owned, the auto shifter connector plugs are always present, just not used).

 

The white plug on the VVTI 6spd shell has a LOT more connectors than are present on the UK auto shifter. Some may be for the manual shift buttons the VVTi cars had which may explain the difference.

 

I also have another pre-facelift auto TT car which has been converted to NA manual so will try and get some pics from that one too for reference.

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On Sunday Steve and I spent some time going over the connectors and wiring diagrams. What we found:

 

- The auto box connectors are all plugged in correctly (Solenoid plugs, speed sensors & temp sensor)

- The plugs on the shifter itself do not appear to have any relation to the box solenoids, they simply light the dash and tell the ECU if it's in Manu mode or not. We can't see any way they would effect the box being able to engage a gear

- The ECU is detecting the gear selection when the shifter is moved. It shifts the RPM slightly upwards when going to a driven gear.

- The box has enough oil in it

 

However, the box still refuses to engage any gear.

 

We've been over the wiring diagrams and can't see anything that is immediately wrong. The only bits not wired in is the shifter connectors and the kick down switch (Neither of which, from a wiring aspect, appear to have anything to do with the box being able to engage a gear)

 

This is a last ditch request for bright ideas before plans are changed again and install a manual box. Hope you guys have some ideas :)

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Good question. We found that two sockets on the UK shifter do not fit the VVTi dash loom plugs. Ideally we'd like to check a VTTi wiring body diagram but haven't found one so far. Because of this we can't even guess which pins should be matched up. That said, the body loom doesn't appear to have any impact on the gear selection process (at least according to the UK wiring that is in place).

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If the ECU isn't connected to the gearbox solenoids you can change gear manually, but, according to http://www.autoshop101.com/forms/AT25.pdf:

L = Low (1st)

2 = 3rd

D = overdrive (4th)

 

Thanks Gareth, very useful, that might help in case it doesn't like Drive. I will keep in mind when trying to move it at the weekend. The connector on the box itself is plugged into the engine bay wiring loom and therefor ECU, but I have no kick-down switch so manual shifting might be needed.

 

If I read the pdf you linked to correctly it will work without the shifter mechanism plugs disconnected. I guess I will find out soon :)

 

Does it move when you select 1/2/D with the gearbox disconnected from the ECU?

Does it move when you select reverse?

 

If it doesn't, that suggests a problem with the 'box.

 

MANUAL SHIFT TEST

The manual shift test is used to determine if the cause of the malfunction is electrical or hydraulic. The electrical connector for the solenoid is disconnected at the transmission, disabling the shift solenoids. The transmission is shifted by moving the gear selector to Manual Low to start the vehicle moving. The first upshift occurs when the lever is moved to Manual Second. The transmission should shift into third or overdrive gear depending on the transmission model. An A-140, A-240, or A-340 series transmission will shift into third gear in Manual Two position, whereas an A-540 will shift into overdrive. The A-140, A-240, and A-340 will shift into overdrive when the gear selector is moved to the Drive position.

If the transmission upshifts as described, the problem is likely to be found in the electrical system... If the transmission does not upshift as described, the problem is likely to be found in the hydraulic system.

Edited by garethr (see edit history)
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Thank you gents :)

 

Does it move when you select 1/2/D with the gearbox disconnected from the ECU?

Does it move when you select reverse?

 

If it doesn't, that suggests a problem with the 'box.

 

MANUAL SHIFT TEST

The manual shift test is used to determine if the cause of the malfunction is electrical or hydraulic. The electrical connector for the solenoid is disconnected at the transmission, disabling the shift solenoids. The transmission is shifted by moving the gear selector to Manual Low to start the vehicle moving. The first upshift occurs when the lever is moved to Manual Second. The transmission should shift into third or overdrive gear depending on the transmission model. An A-140, A-240, or A-340 series transmission will shift into third gear in Manual Two position, whereas an A-540 will shift into overdrive. The A-140, A-240, and A-340 will shift into overdrive when the gear selector is moved to the Drive position.

 

I didn't read your original post correct, apologies. We didn't try it with the auto box disconnected from the ECU, if I understand you correctly, I should unplug the couple of solenoid plugs from the auto box and try to manually shift. Correct?

 

That's where the problem is, as I sneakily edited into previous post, without the shifter connected the ECU will think it's in neutral.

 

You might be able to fudge it, by opening the neutral start circuit after starting, before engaging "D".

 

Okay, that makes sense, though I cannot see it in the wiring diagrams. I'll try and find those dreaded VVTi loom diagrams and see what needs to be bridged to trick it

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...We didn't try it with the auto box disconnected from the ECU, if I understand you correctly, I should unplug the couple of solenoid plugs from the auto box and try to manually shift. Correct?..
That's correct. The ECU controls the 1/2/3/OD gearchanges through the solenoids. If the solenoids are disconnected you still have manual control of 1/3/OD (and reverse, I assume) on an A340. Edited by garethr (see edit history)
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You've or someone has already bridged it, the neutral/start wires on the auto loom that get joined when used with manual gearbox.

 

Sorry David, I'm not following you here. I haven't bridged anything but perhaps the garage that had the car before has. What I can say is that the car will only start when P or N is selected on the shifter, it locks out the start in any other position (Which I believe is normal operation)

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I have been answering your question informed that the shifter isn't connected?

 

Correct, the shifter plugs are not connected as they don't match. The physical connection between the shifter and the arm to the gear selector is in place and positioned correctly.

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I'd check again. Put the lever in Park and then you should not be able to turn the propshaft, or roll the car forward or back, handbrake off, obviously.... Then put in R and D and you should be able to roll the car. AFAIK the box should select gears with the connector to the solenoids removed, but I am no auto box expert. It'll be something simple, but finding just what in a mongrel car could be tricky :)

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Without that plugged in, the neutral start wires must be joined somewhere or it wouldn't start.

 

Just to confirm this David, the gear shifter has no plugs connected as they are different. With the car in P it will start, if we shift it into a gear the car will not start.

 

We have found that with the engine running, when selecting gears the engine note does seem to change but there is no drive.

 

I am going to go over the wiring diagrams more thoroughly to see if we have missed anything.

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