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Discussion Starter #1
I have a TC that is intermittent at locking up. It threw a PO740 a few days ago. The TC wasn't locking in. Then it started working again for a day. The light went out on its own. Today it came back on and the TC isn't locking again. Where is a good starting place to find this problem. I checked the plug on the tranny today and made sure it was plugged in good. It seem to be. Should I pull the wiring harness from the tranny to where it plugs on the motor and check it for continuity ? Or start somewhere else?
 

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It's almost always a dead solenoid -- it can be accessed from underneath via removing the transmission pan. It it has never been removed, it's probably in need of a fluid change anyway (and you can then weld in a drain plug to make fluid changes easy for the next time).

I believe 1996 was the year that the relay that drives the TCC lockup solenoid was replaced with a transistor that directly drives it (inside the computer), buy I could be mistaken.

Intermittent failure would point to the solenoid on its way out, to me. Does it fail hot and then work again after sitting overnight?
 

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While it may very well be the solenoid, I would start with the easier option of checking the wiring to the connector - it would be a bit frustrating to find, after going through the effort of dropping the pan, that it was the wiring or connector all along. Personally, I would think that continuity would be a good place to start, and would jiggle the wiring while testing to make sure that there isn't an open/short somewhere that is intermittently causing your issue.

Edit: While this may not help, fixkick once advised that he ran wiring from the connector to inside the cab, and put a 12v bulb on the wiring - this way he could actually see if/when the TCC was getting the voltage signal to lock up/release.
 

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Discussion Starter #4
Colonel I haven't checked it temp wise. Ill see if its working cold this morn. I know it wasnt working w it good and hot.
Bex I don't have a wiring diagram which wire is supposed to get 12v? Ill check continuity too. That plug on the tranny is in a tight spot!
 

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Especially if it is intermittent and generally works cold.
 

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Obdii

I don't believe anything is specific to Suzuki in OBDII. In OBDII the codes are ALL standard (or generic) which was the whole idea behind the change to ODBII.
 

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Ok, that's what I thought. My 96 has not had issues with the TCC (yet).

There is still the solenoid that opens the hydraulic passage to provide pressure to lock the TC clutch, however. It is just directly driven by a transistor in the ECU.

Is that the clarification you were looking for?
 

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The second digit of an OBD2 code indicates if it is specific to a manufacturer or generic. A zero indicates generic - a one indicates specific.
OBD-II Codes Defined
 

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Discussion Starter #10
Ok English guys Lol! So do I have a solenoid or is mine controlled by the ECM? I'm sorry but I'm not too smart on diagnosing things. Mine is the 98 model 3spd. I have a new TC in it. Had the transmission out and at my local tranny shop. Told him to do anything that it needed. He put a pump in it and new seals. He said the bands looked really good. Of course new filter and Dextron VI fluid.
 

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Discussion Starter #12
Well if your saying you just had the transmission overhauled why don't you take it the guy that did it and ask him why the converter isn't locking up?
I did talk to him and he said bring it back. Just thought since it was working sometimes it could possibly be something I could check. Ill probably end up just taking it to him because like I stated I'm not really good at tracking problems down. Sometime though I'd like to try to fix something on my own!!
 

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All the 3 speeds have a solenoid for TCC lockup. The relay just drives the solenoid in the older cars. yours should be directly driven by the ECU, since you have a 1998. Sounds like you should have taken it back for warranty when the code showed.
 

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You could of curse connect a lamp to the Lockup circuit, locate it in the cab. When the lamp lights up the TC should accordingly lock up...

Philip
 

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All the 3 speeds have a solenoid for TCC lockup. The relay just drives the solenoid in the older cars. yours should be directly driven by the ECU, since you have a 1998. .
I'm not sure that this is correct. The 3 speeds, regardless of year, are pretty much the same - the TCC is controlled by a relay ground that is in the ECU, and the relay governs the solenoid. Other than that, the ECU does nothing on the 3 speed tranny - it is otherwise purely mechanical, AFAIK.
 

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Just curious as to the source of this information? Following post is for a 1998 3 speed Trackick, and strangely, they are still testing the relay.
http://www.suzuki-forums.com/suzuki-sidekick-escudo-vitara-geo-tracker/20827-tcc-solenoid.html
Are you saying that all the posts here for 1996-1998 3 speed trannies, people are replacing/testing a non-existent TCC relay??
You have previously advised that you are getting much of your info from a 'change in diagram' in a Chilton's book. Is that your source?? Are you sure they aren't confusing the diagram of the 4 speed tranny with that of the 3 speed??
 

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Just for your info, the Suzuki EPC also indicates a TCC lock up relay for ALL 3 speed trannies up to 1998.
 

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Discussion Starter #19
When I drove to work this morning. When I left the house and hit the interstate the TC locked. Drove several miles exited to another road and when I got back up to speed it didn't. Looks like a trip to the tranny shop is in order!!
 

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Driver circuit - Wikipedia, the free encyclopedia

All 3 speeds have a solenoid for TCC lockup. There are many differences in the vehicles/ECUs so it is possible that there is a relay on some and some are directly driven. I'll have to look at my 1996 and its FSM when I get back to CA next week.

I have read multiple threads here when I was neck deep wrestling with the most complex TCC problem that anyone's had on this forum that stated that the TCC was directly driven by the ECU 1996+, but never experienced it personally, hence the question mark a while back. . There is a thread I started that goes through all of the diagnostics and repairs that may be worth looking up, PVTCook.
 
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