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  #1  
Old 02-03-2010, 07:07 PM
hawaii-svx hawaii-svx is offline
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Please Help! TCU code 25

After my SVX warms up and I drive it for 10 or so min, it stops shifting it just stays in 2nd gear, It wont shift up or down. If I pull over and restart the engine it will shift fine for a mile or two but then gos back to second gear and stays there. If I disconnect the battery and let the computer relearn it will drive fine for a day or two but then gos back to the same.
The engine is running fine. I pulled the TCU codes and came up with code 25 Engine Torque Control signal. To the best of my knowledge this is the code for the crankshaft/camshaft sensors but I have no idea what there test range is or if they are even the problem.
P.S. the car has shifted hard at very low speeds (2-6mph range) from 1st to 2nd gear for the last year or so.

Any help that can be given would be greatly appreciated,
Thanks, Paul
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  #2  
Old 02-03-2010, 07:44 PM
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Re: Please Help! TCU code 25

Kia ora Paul,

The TCU receives, and is dependant upon, a single signal for torque control from the ECU, Therefore you should also run a check for ECU codes.

The symptoms you describe could very well indicate a faulty TPS (throttle position sensor.) i.e. a faulty area of connection within the conductive plastic resistive element, probably close to the first point of operation. This might only involve a deposit of dirt. Have a look in the how too section regarding, cleaning, setting and testing, but ignore the test board and measurement stuff.

If you have electronic or audio equipment knowledge, I can advise regarding a more definitive TPS test which, is worth trying.

Cheers, Trevor.
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Last edited by Trevor; 02-03-2010 at 07:49 PM. Reason: Extra point added.
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  #3  
Old 02-03-2010, 10:52 PM
oab_au oab_au is offline
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Re: Please Help! TCU code 25

Quote:
Originally Posted by hawaii-svx View Post
After my SVX warms up and I drive it for 10 or so min, it stops shifting it just stays in 2nd gear, It wont shift up or down. If I pull over and restart the engine it will shift fine for a mile or two but then gos back to second gear and stays there. If I disconnect the battery and let the computer relearn it will drive fine for a day or two but then gos back to the same.
The engine is running fine. I pulled the TCU codes and came up with code 25 Engine Torque Control signal. To the best of my knowledge this is the code for the crankshaft/camshaft sensors but I have no idea what there test range is or if they are even the problem.
P.S. the car has shifted hard at very low speeds (2-6mph range) from 1st to 2nd gear for the last year or so.

Any help that can be given would be greatly appreciated,
Thanks, Paul
Hi mate, I would check for a loose plug to the TCU and down to the gear box at the rear of the engine on top of the bellhousing.
The code 25 is from the TCU finding a fault, when trying to signal the ECU to turn the power down. That is why you are having the hard shifts.
There could be a few troubles caused by a loose TCU plug.

Harvey.
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  #4  
Old 02-04-2010, 07:43 PM
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Re: Please Help! TCU code 25

thsi code is a PIA ,its just a signal between the ecu and tcu ,giving a specific voltage to the tcu ,check for loose plugs or you can do sliding resistance test on the pins ,yellow connector b59 22 pins black yellow wire at pin 20 for the ecm
black connector 16 pins black yellow wire pin 16 for tcm
key on engine off out put of ecu 4 to 5 volts
unplug tcu key on engine off 4 to 5 volts
it could need a ecu or tcm depending on your finding s
i have a tcu if needed
charlie
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  #5  
Old 02-05-2010, 06:48 PM
hawaii-svx hawaii-svx is offline
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Re: Please Help! TCU code 25

I finally had a chance to work on the car today and I checked everything that was you guys recommended.

Trevor, I installed the TPS about a year ago but I still pulled out the multimeter and the TPS was at a solid 0.480v and had a smooth volt transition all through the range of movement.

Harvey, I found the two plugs on top of the bellhousing and made sure that they where all plugged in nice and tight. I also for good measure checked the connections on the left side of the engine, TCU and ECM connections.

Charlie, you are correct this problem is a PIA. I did as you suggested and checked the voltage at the 'b59 22 pins black yellow wire at pin 20' on the ECM with the key in the on possition and it was 4.59v.
At the TCU black and yellow wire unpluged from the TCU with the key in the on position there was 4.6v.
If I plugged the 16 pin plug back into the TCU and checked the same wire with the key on it was 4.60v

Unfortunitly I am still experiencing the same problem of code 25 and remaining in second gear.
I truly appreciate the help you gents are giving and any other advice or suggestions would be gratefully excepted.

Thanks again,
Paul

Last edited by hawaii-svx; 02-06-2010 at 01:45 PM.
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  #6  
Old 02-05-2010, 07:48 PM
trophy956 trophy956 is offline
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Re: Please Help! TCU code 25

Hi Paul
I Went Over The Flow Chart Again And The Signal Comes From The Ecu To The Tcm ,if You Have No Volts With The Tcm Unplugged When You Have 4.59 At The Ecm ,you May Just Have A Bad Tcm ,do One More Check Unplug Both Connectors And Check The Resistance Of The Wire 0.04 Should Be Correct ,i Will Check The Update Manual On Line Tomorrow At Work ,i Checked Aldata And They Have The Same Chart,i Ll Let You Know What I Find
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  #7  
Old 02-05-2010, 08:40 PM
hawaii-svx hawaii-svx is offline
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Re: Please Help! TCU code 25

Charlie, I checked the resistance on that wire and it read 0.00oms

Thanks again for your help,
Paul
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  #8  
Old 02-05-2010, 09:00 PM
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Re: Please Help! TCU code 25

Kia ora Paul.

Special thanks for your explicit and well tabulated run down.
Not what one normally expects here.

At this stage it is known that:-

(a) The TCU is not receiving a correct signal from the ECU.

(b) The problem is intermittent.

(c) The problem can be corrected by interrupting battery voltage. Therefore Something held in “memory” must be involved.

You have advised “The car has shifted hard at very low speeds (2-6mph range) from 1st to 2nd gear for the last year or so."

Quote:
Originally Posted by hawaii-svx View Post
Charlie I did as you suggested and checked the voltage at the 'b59 22 pins black yellow wire at pin 20' on the ECM with the key in the on possition and it was 4.59v.
(1)Therefore there there should be voltage available at the opposite end of the black/yellow wire.

Quote:
At the TCU black and yellow wire unpluged from the TCU with the key in the on position there was 0.0v.
Presuming that you were measuring output from the plug, and the ECM/ECU was connected, the voltage did not arrive at this end of the wire.

Quote:
If I plugged the 16 pin plug back into the TCU and checked the same wire with the key on it was 4.60v
The voltage measured was being supplied from the TCU.

Reference (1) Did you check with the plug inserted or removed?

If the plug was not in place you have not tested against a faulty plug connection or wire to plug connection. You should stick a thin sharp object through the insulation of the wire just after it exits the plug, and measure for voltage within the wire.

In the event that all was well at the ECM/ECU connection, the black/yellow wire must be open circuit and faulty).

(1) If you were measuring with the plug removed there should have been voltage returning from the TCU.

However this does not add up with add up with (c) above unless somehow a very strange break in the wire is involved. There again these test do not cover a fault in the transmission and receipt of the actual signal.
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  #9  
Old 02-05-2010, 09:15 PM
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Re: Please Help! TCU code 25

Quote:
Originally Posted by hawaii-svx View Post
Charlie, I checked the resistance on that wire and it read 0.00oms

Thanks again for your help,
Paul
Only read this after I posted.

Your advice is confusing. 0,000 Ohms in fact indicates a completed circuit with zero resistance. However this is a very common error and I take it that the wire completed a circuit, but your ohm meter was incapable of measuring the resistance of same, and recorded zero ohms.

Damn it we are back in square one. However please take note of my advice regarding plug/socket connections verses the actual wire.

Where I have mentioned "memory", this is a term which can be applied to both a mechanical and an electrical event. When either is intermittent ----##$$%%!!!!!
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  #10  
Old 02-06-2010, 03:27 AM
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Re: Please Help! TCU code 25

The ECU supplies approx 5 volts on the Torque control wire. The TCU pulls this voltage down to zero (ie grounds the wire) when it wants to signal the ECU to reduce power for a gearshift.

It sounds like a faulty TCU to me.
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  #11  
Old 02-06-2010, 07:51 AM
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Re: Please Help! TCU code 25

Don't forget to check, remove and clean the ground wire on the back of the intake manifold on the passenger side near where the vacuum line exits the intake manifold to go to the FPR.
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  #12  
Old 02-06-2010, 02:17 PM
hawaii-svx hawaii-svx is offline
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Re: Please Help! TCU code 25

There was an error on my previous post I said "TCU with the key in the on position there was 0.0v " it should have said 4.6v(sorry for the confusion Trevor). I believe that my ground wire must have slipped while I was measuring the voltage output to the TCU plug (its a PIA to work down there).

To recap, the ECM black and yellow wire is outputting the correct 4.6v to the TCU and there is no resistance in the wire.

Trevor, I did go back and do the measurements socket to socket and I did get more accurate results.

Phil, It is starting to look more like it is the TCU. I will start to look at finding one today.

Svxfiles, I checked the ground wire that you mentioned and it was giving solid voltage and and very little resistance. This also inspired me to check the the rest of the ground connections on the car and they all seem to be in good shape.

Any advice as always will be gladly excepted,

Thanks again,
Paul
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  #13  
Old 02-06-2010, 05:54 PM
oab_au oab_au is offline
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Re: Please Help! TCU code 25

This problem is not caused by one fault. The Torque Control, and the staying in 2nd gear, can not be related to one normal fault. The whole TCU's operation is being affected.
As you have found there no faults with the plugs or grounds, have to suspect the TCU as Phil says.

Harvey.
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