Why would my TCC stop locking up after i've been driving on the highway for a while? I don't think it's computer related, i checked the TPS and it is fine even when this is happeneing, and MAP or CTS would throw a code pretty readily if it was bad. I haven't checked the power side coming off the brake switch, but doens't seem likely that that would intemrittently fail ONLY after driving for a while.
Seems like maybe the TCC solenoid is dying after being run for too long? If thats the case, how hard would this be to fix? i.e., is it easily accessible if i drop the pan or would i have to take half the tranny apart to get to it?
...ed

 

That is strange, but no it's not hard to swap out from the bottom.

 

Heat=Resistance

It is quite possible that after driving for a while, the TCC solenoid may be getting hot enough and becomeing "open" preventing it from operating. Its easy to replace. I don't remember on the 700, but on the 4L60-E, the solenoid is part of the trans internal wiring harness (same as the 3T40 also) so expect it to be $80+. It is easy to replace though. Are you sure it isn't engageing?

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Are you sure that you car is going into closed loop? A "weak" CTS (or colder T-stat) won't throw a code, but if your ecm does not see a warm enough temperature to put it into "closed loop", your tranny won't lock.

 

Damn it sucks being treated like a mortal.
Yes i am 100% sure i am in closed loop. After i've been driving 80-100 miles i notice the TCC isn't locked. The temperature will be running the same as normal during this (and considering TCC starts working on my car as soon as the temp guage comes off the bottom i'd rule this out anyway, i'd also rule this out anyway, cuz even in open loop the TCC should lock by 70mph)Like i said, i checked teh TPS, as i figured maybe it was screwing up in the low ranges after getting hot, seemed unlikely but possible. I rule out the MAP cuz that would severely affect driveability if it was going bad. I rule out the VSS cuz #1 my speedo works, and #2 the ECM would **** if it wasnt getting a VSS signal if somehow that side of teh circuit was bad. I also checked the TCC plug while hot to make sure it was still fully seated. Yes i am 100% positive it isn't locking, i feel and appreciate the TCC in my driving, once it isn't locked it's like driving a different car.

But anyhow, thats cool that it's easy to get to from the bottom. I need to change the tranny fluid soon anyway. Is it a pretty straightforward R&R or do i need to get a hold of a manual/diagrams?
thanks...ed

derf..forgot my sig in both posts...anyhow, this is in my 92 Z28 vert....LB9 M5 (LOL...j/k, if you don't know what part i'm kidding about i'm asking dirk to ban you for thinking i'm that dumb...lol)

[This message has been edited by Ed Maher (edited February 20, 2001).]

 

Gee ed, I think I know why your converter wont lock...! )

But seriously, Most ppl wouldnt/wont even catcht hat


Ill assume You mean a BMW when you say M5.. )




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60 Ranchero - Project ( Money Hole )
85 Sport Coupe LG4 - Daily Driver

Just another Hot Rod kid, or thats what they all tell me.
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One thing you can try is the O ring on the input shaft of your700R4.Apparently this can break down and allow oil to by pass it and that in effect will feel like the convertor is unlocked.Ive got a similar problem with mine in so far as it does not appear to fully lock up.I have tried a new convertor and a new lock up solenoid and also I have bypassed the ecu and all sensors som I can lock up at the flick of a switch so I have eliminated many of the things it could be.I will soon be replacing this O ring so ill let you know the result

 

But wouldn't that O-ring problem be a factor all the time. My TCC works beautifully, then after 80-100 miles it stops locking entirely. Not even a whimper of a slipping lock-up.
...ed

 

Powermite, that o-ring should have been inspected/replaced when the tc was replaced (they did you a dis-service if you were already having that problem). If it is nicked or deteriorated, it won't be able to hold pressure and will pass fluid pretty much at all times.

Ed, the only way that that o-ring could allow the tcc to not lock after 80-100 miles of warming up would be if someone put a standard buna-n or other material o-ring on there instead of the viton material o-ring and it is changing size/distorting due to the heat/tranny fluid. By the way, that o-ring is the same p/n as the o-ring on the top of the tcc solenoid assy.

Last time I bought any tcc solenoids, they were about $27-33 from the GM dealer. I bought two that time (both different p/n's). My book references approximately 12-16 different tcc solenoid p/n's due to the many different valve body wiring versions GM did. You have to know the coil insulator color and/or the 4 digit number on the bottom end of the tcc solenoid to know for sure which one you need. It can also help to sketch out the connections on your tcc to valve body to help assure you get the right one.

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KevinP92Z
92 Z28 383 SLP cam,SLP headers,SLP 2ontheLeft,Trick Flow TW heads & pistons,Edelbrock base,Accel SuperRam,52mmTB,Scat Crank & forged ConnRods,MSD 6AL,SLP convertor,Baer 13/12" Track,Moser axles,Hotchkis,Genuine GM 3.42s,SLP HD Torsen,17x9" chrome SS rims
96T/A w/SLP Ram Air,SLP 2ontheLeft, Bilsteins, Baer, Hotchkis, Genuine GM, Torsen
76 4X4 Blazer 400TPI project

 

Just wondering, how does tps relate to the TCC ? And also if your tps is disconnected what happens to TCC ?

 

Hello Ed. My name is F.C. Has trans been worked on recently. Sounds like you have a electrical problem that is minor. bad wiring harness, or electrical short some where. If electrical is OK Check your pressure switches. Blow air into switches (use air gun without rubber and screw into air gun) and see if pressure switches are holding.

 

Thanks for the heads up kevin. Is there any way they can reference what *should* be in there based on year/application, or is it pure potluck? I'd like to at least pick up the likely cuprit for when i change the tranny fluid, and if it isn't the right one i'll crack it open again with the right information.
It sucks i will likely be doing this at my parent's house, which has no GM dealers anywhwre near it. Else i could drop the pan, figure out the right one and go pick it up mid-job. I guess i could do it at my apartment, but i don't know how my neighbors would like the mess that would likely happen.
hmmmm, decisions...
...ed
ps, am i right in assuming that the TCC solenoid is right inside the tranny pan, or will i have to drop the valvebody (and/or need manuals to make sure i get it right.)

 

Ed, You're right that the tcc solenoid can be easily accessed once the pan is down. Two bolts hold it in, you'll just have to watch the wire connections.

As far as determining ahead of time which tcc you have, I'm not aware of one, maybe someone like GMTech knows of a way. Unfortunately, my ATSG Tech Service Book lists each of the wiring "types" (my 92Z has a type 9, my 76 K5 blazer 4x4 with an 87 trans has a type 2). On each diagram they list the 2 digit "model codes" that are typically used on that wiring type. There are approximately 30 two-digit model codes (YT, YL, YK, YN, YP, TS....MA, MC, MF, ...) and the book doesn't list how to distinguish. Most wiring types have 3-6 models or more listed using that type.

Two choices. At your apartment, you could plan to hoist car, drop fluid & pan and ID the solenoid. Just have enough fluid to refil. Don't worry about the filter at this stage. Then once you have the right solenoid, repeat with the filter change. This would help dilute out the old fluid in the torque convertor, and if your fluid change has been a bit on the long side, this extra change only costs you a few quarts of tranny fluid.

Otherwise, you'd have to find transportation to a GM dealer ahead of time (hopefully they even have the part in stock.

My page scanner's down, but I could fax the pages to you if you want. It does have the GM p/n's on it. Let me know since I have the book here with me now. By the way, I found the price for the type 9 in my 92Z whcih has more wires than some of the tcc solenoids, and it was $27.28.

Kev

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KevinP92Z
92 Z28 383 SLP cam,SLP headers,SLP 2ontheLeft,Trick Flow TW heads & pistons,Edelbrock base,Accel SuperRam,52mmTB,Scat Crank & forged ConnRods,MSD 6AL,SLP convertor,Baer 13/12" Track,Moser axles,Hotchkis,Genuine GM 3.42s,SLP HD Torsen,17x9" chrome SS rims
96T/A w/SLP Ram Air,SLP 2ontheLeft, Bilsteins, Baer, Hotchkis, Genuine GM, Torsen
76 4X4 Blazer 400TPI project

[This message has been edited by KevinP92Z (edited February 22, 2001).]

 

I was pretty darn sure that coolant temp & road speed governed the TCC lockup, not closed/open loop...


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