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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 |
#2
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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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Trevor, New Zealand. As a child, on cold mornings I gladly stood in cowpats to warm my bare feet, but I detest bull$hit! Last edited by Trevor; 02-03-2010 at 07:49 PM. Reason: Extra point added. |
#3
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Re: Please Help! TCU code 25
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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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One Arm Bloke. Tell it like it is! 95 Lsi. Bordeaux Pearl, Aust. RHD.149,000Kls Subaru BBS wheels. 97 Liberty GX Auto sedan. 320,000Kls. 04 Liberty 30R Auto Premium. 92.000kls. |
#4
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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 |
#5
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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. |
#6
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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 |
#7
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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 |
#8
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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:
Quote:
Quote:
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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Trevor, New Zealand. As a child, on cold mornings I gladly stood in cowpats to warm my bare feet, but I detest bull$hit! |
#9
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Re: Please Help! TCU code 25
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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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Trevor, New Zealand. As a child, on cold mornings I gladly stood in cowpats to warm my bare feet, but I detest bull$hit! |
#10
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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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Subaru ECU and TCU Website 1992 Alcyone SVX Version L 1992 Alcyone SVX Version L 1994 Alcyone SVX S40-II 2004 Subaru Legacy 2.5 SE Sports Tourer 1996 Subaru Legacy 2.2 GX Wagon 1988 Subaru Justy J12 SL-II |
#11
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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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www.svxfiles.com The first SuperCharged SVX, the first 4.44 gears, the first equal length headers, the first phenolic spacers, the first Class Glass fiberglass hood, the first with 4, 4.44s in his driveway Fiberglass Hood thread My locker 4.44 Swap link |
#12
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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 |
#13
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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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One Arm Bloke. Tell it like it is! 95 Lsi. Bordeaux Pearl, Aust. RHD.149,000Kls Subaru BBS wheels. 97 Liberty GX Auto sedan. 320,000Kls. 04 Liberty 30R Auto Premium. 92.000kls. |
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