Messed up my TCC lockup!

[atom_c]

I set up a toggle switch to manually lock up my torque converter on my 1995 truck. I tapped into the brown wire on the circular wire connector on the transmission as described here http://blog.heathdiesel.com/2005/11/...converter.html
I cut the brown wire near the transmission, spliced on wires to both ends, and brought them up and through the firewall to my 3-pole toggle switch. I hooked the ECM wire to one side, the trans. end to the center, and grounded the other end.

It worked great (for a few miles). The computer locked it up at 45 mph, just like always, and if I flipped the switch I could force it to lock at any speed. I hooked up a LED indicator light to the center pole and ground of my toggle switch. When the circuit was energized (TCC unlocked) my light was on. When the ECM or I locked up the torque converter the light went off (circuit not energized).

Today I drove my truck and the ECM no longer locks up the converter at 45 mph or any speed. I can still manually lock it up. I unhooked the led light thinking it might be messing up the works, although it only draws a few milliamps. That didn't help. The ECM is still not locking it up.

Help!? Any ideas?

Thanks
Adam

[ToddMeister]

Temporarily hook it back up to stock and see if the PCM locks the converter. That would rule out the new switch causing the problem.

[moondoggie]

Good Day!

I'd check for tranny codes - might be one set that doesn't light the SES light. I'd do it soon - some codes are only stored for X (50?) restarts.

Have you talked to Bill Heath? What's his take?

Blessings!

[joed]

I recently did this mod on my dad's 95 and had the same problem...I ended up switching the connections on the switch to make it work. I think I flipped the end terminals that go to the ground and even reversed the trans connections. It works now as it should with auto mode in one position and manual (forced lockup) in the other.

I too, used a red-lighted switch figuring it would nice to have it light up when manual mode is on - but it wouldn't work correctly wired that way. The way it's currently configured, the switch light does not come on in either mode.

The only drawback I've found is that when you use manual mode, the PCM stores an 83 code - maybe this forced mode always will?

Hope that helps. Joe.

[rjwest]

Had the same problem on a gasser,

I cleared it by unhooking the pcm for a few hours,

I do not know why this worked or why the TCC lock
up failed, My guess is I left the TCC forced locked and
tryed to stop, PCM killed the quad driver circuit as a fail safe..
( thats the circuit driver in the PCM)

I did use the Forced TCC lock up afterward but always rembered to open the TCC above 35 MPH.
Same speed that the torque loc releases the TCC lock up.

[atom_c]

Thanks for the suggestions. I did call Bill Heath, and he was very helpful and easy to talk to. He said that if I flipped the toggle switch just after the ECM locked up it could throw a code 83. In any event, I checked codes and had an 83. I am not completely familiar with clearing codes on my 95. I read I push the brake and accelerator at the same time while checking? When I did this it started flashing once and then twice. What does that mean?

It seems to have worked, because my converter locked up at 45 again. I will need to figure out how and when to lock up manually without setting a code.

Thanks again,
Adam

[DmaxMaverick]

......I am not completely familiar with clearing codes on my 95. I read I push the brake and accelerator at the same time while checking? When I did this it started flashing once and then twice. What does that mean?

It seems to have worked, because my converter locked up at 45 again. I will need to figure out how and when to lock up manually without setting a code.

Thanks again,
Adam

It reset. Flashing 12 means the PCM is entering diagnostic mode, and no codes are stored.

[atom_c]

Still a bit messed up...

I haven't figured this one out. My TCC will not lock up via the ECM when I first drive the truck from a cold start. For example, last week I drove into work (9 miles/cold morning) and it would not lock up the whole way (unless I manually flipped the switch). The truck sits in the sun all day and I start home and it immediately locks up when I hit 45 mph and works fine all the way home. Other days on short trips it would not lock up at all. Today, I start it and drive 3 miles to pick up my daughter, drive 5 miles and buy groceries, and then finally on my trip home it locks up at 45 and works fine. Is it temperature related? Random? What's up?

Also, I cleared my code 83 and it comes back immediately even if I don't use my manual lock up switch. I tested this by clearing the code, starting the truck, turning it off, and the code 83 was already back.

I will call Heath again when I get a chance. Anyone have ideas?

Thanks
Adam

[ToddMeister]

The trans temp has to exceed a limit before the TCC locks up. The colder the outside temp, the longer it takes before lock up is enabled. It was programmed this way to warm up the transmission faster.

On cold days it takes about 3-5 miles before my TCC lockup starts working. I also have a manual switch, so I can lock the TCC anytime.

Sounds like your truck is working okay.

[bcbigfoot]

I have a manual lockup switch as well in a 93 everything seem to work well for me. There is a temp. sensor in the trans that won't allow lockup when the trans is cold and have been told (don't have first hand experience)that if the trans overheats the lockup will engage to help get the temps back down.

I get a code 83 but beleive only when I use the manual lockup switch.

[ECMProgrammer]

I'll throw in my two cents...you actually can't manually command lockup with a toggle switch. The computer monitors lockup, and the states in which the system is in--therefore when you command lockup when the PCM doesn't want lockup--it sets a code, and lockup is inhibited.
The only way around this is to rewrite the software to allow switched lockup.

Lyndon
www.ecmprogrammer.com
Westers Garage
1-888-WESTER-1

[atom_c]

I had a chance to drive a bit over the weekend. The toggle switch most certainly does cause the converter to lock up. What I don't have enough knowledge to figure out is why it takes so much longer to lock up on its own with some additional wire and a toggle switch in the brown wire circuit. In the past it would lock up immediatley at 45 mph if the outside temps were above 40 and it would take 2-3 miles after a cold start in freezing temperatures. Now it seems to take about 6-10 miles of driving even in moderate tempatures.

I did not know the brown wire had anything to with the tranny temp sensor. Or does the ECM do things a bit different with a code 83 on record? I could live with the situation as is. I can always do a manual lockup with the toggle switch if I need to get flying down the road and it hasn't warmed up enough to lock on its own. Just trying to figure it out......

Thanks for the responses,

Adam

[Warren96]

The brown wire has nothing to do with the temp circuit.That would be the black yellow wire.

[atom_c]

I didn't think that the brown wire had anything to do with the tempature sensor. That is why I am baffled by my belated lock up. I will get under the truck soon and make sure that the connector on the tranny is tight. I may have wiggled some other wires a bit when I got to the brown wire.

Thanks all,

Adam

[joed]

Adam, have you made any more progress with this?

Now that my dad has had a chance to drive his truck some with this mod., he is experiencing the same thing - delayed TCC lockup in the 'auto' mode. Just as you have noted, it seems to take several miles before it will lock. I'm wondering if the colder weather is having an effect, although I don't remember noticing this issue last winter, before this mod. was done.

Does anyone know the minimum trans. temp before the TCC will lock up? His trans. temp gauge shows around 150, I think.

It is odd that just adding some wire and the switch would delay the PCM control so much - maybe the extra wire adds enough of a voltage drop to affect things?

Also, as you noted, the code 83 always seems to be there, whether you use the manual mode or not.

Thanks. Joe.

[sailun]

Hey guys,

What's this about the TCC locking up at 45 mph ? Mine doesn't lock up until about 53 mph. In other words, almost only on the highway.

What is normal ? Is it different for trucks and Burbs ?

Or is this related to a tranny shift kit, or ECM upgrade ?

Thanks for the help.

[JohnC]

Hey guys,

What's this about the TCC locking up at 45 mph ? Mine doesn't lock up until about 53 mph.

Lockup is based on transmission output shaft, not road speed. With those 3.23 gears, I'm surprised yours ever locks up! ;)

[sailun]

John,

I'm convinced now that the gears must be 3.42's, I'll change out that info shortly.

Tell me more about lockup and shaft speed, cuz the only time I see and feel lockup is in overdrive at 53 mph on the highway.

If I'm driving at 45 or 50 in overdrive, should the TC be locked up ?

Kevin

[JohnC]

Tell me more about lockup and shaft speed, cuz the only time I see and feel lockup is in overdrive at 53 mph on the highway.

That's probably about right. If you had lower gears it'd lock at a lower road speed, but the same engine RPM's. Also, at least on the '95 model year, the light duty trucks locked up about 5 mph slower than the HD version. If you can get it up to 53 mph in 3rd, it should lock up there as well. Heavy throttle will delay lockup somewhat.

[atom_c]

I have not found out how to cure my little "belated" lock up problem. I know for sure that before I put the lock up switch in I would drive about 3 miles, at most, in freezing weather before it locked up. After putting in the switch it takes at least 10 miles even in moderate temperatures. The good news is that if I need to go on the freeway I can just flick a switch and I am locked up. If anyone has any more ideas or knowledge of what exactly is causing this delay in lockup, please chime in. I know it is related to transmission temperature...



Adam

[joed]

Yeah, it is perplexing as this mod. doesn't directly involve the temperature circuit (at least I think...)

I'm beginning to think the code 83 is throwing things off. Does anyone know what the PCM does when a code 83 is set?

I can look up the 96+ OBD II setups, but not the 95s and older.

Thanks. Joe.

[ToddMeister]

I'll have a look-see in my factory manuals this weekend and see what code 83 affects.

[bluuzman]

A couple of lines from a manual:

*************************
DTC 83 WILL SET WHEN
- The PCM commands the solenoid "ON" and voltage remains high (B+). OR
- The PCM commands the solenoid "OFF" and voltage remains low (zero volts).
* All conditions met for 2 seconds.
PCM WILL
- Inhibit TCC operation.
- Inhibit 4th gear operation if in hot mode.

DTC 83 WILL CLEAR WHEN
The fault condition no longer exist, and the ignition switch is cycled "OFF" then "ON."
***************************

Based on this it is quite obvious that if TCC solenoid is activated manually (ground the wire), the PCM will set the code and will not operate TCC.

The same manual that I use gave the wire color code "tan/blk" for the TCC control.

Do you keep the TCC locked also at lower speeds? If so, are the shifts harsh? Can the tranny handle shifting with TCC locked? How about durability?

I guess the PCM has different software for different gear ratios, if the TCC lockup will engage at 45mph. If we change to lower ratios e.g. from 4.1 to 3.73, the lockup speed will rise if not updating the software, is this correct?

-a

[Robyn]

The TCC lockup speed will vary some with different ratios.
I have a 94 Burb with 4.10 gears and it locks at 45 mph with light throttle.
I had another Burb with 3.73 and it would lock at 50 mph

Its based on drive line rpm I think and these trucks were stock.

Shifting with the TCC locked is abrupt and really not what the box was designed for.
The TCC is designed to engage at light cruising loads after the tranny has made the shift to 4th gear.
This is totally a tool to extract better mileage from the vehicle.
There is no advantage as far as durability or anything else, it's all about mileage.


I would recommend against running the tranny through any shifts in the locked mode.
I have done this with a 700R4 and its bloody rough and if you get the mph a little too low the suckers will growl and chatter just like lugging a stick shift rig.

The very small clutch surface area in the converter was never designed to tollerate this stuff, again it was designed for cruising and not hard pulling.

Hope this helps.

[bluuzman]

My '95 Suburban is basically stock and it locks TCC at 45mph (4.1 gears) with both 3rd (with "3" selected) and 4th (when using Drive/OD shift position)

If there is no software compensation it's obvious the lockup occurs at different speeds depending on the gear ratio.

However, I'd stay it feels like the torque converter wastes quite a bit of the power of the diesel engine and it is much nicer to cruise with TCC locked - feeling clearly more power, less RPMs... Naturally this all improves mileage a lot.

It well may be true the TCC can not handle high loads as a clutch in a manual transmission but I guess GM should have considered this when programming the PCM ;)

-a

[atom_c]

Thanks Bluuzman. What I still don't completely understand is why it sets a 83 even if I don't use the switch. I have cleared the code started the truck and it comes back immediately.

I usually only use the switch to get it to lock-up in 3rd or 2nd gear. I have not experienced a harsh shift yet. I use it for towing up grades and sometimes for long descending gravel roads.

Adam

[ToddMeister]

Shifting with the TCC locked is abrupt and really not what the box was designed for.
The TCC is designed to engage at light cruising loads after the tranny has made the shift to 4th gear.
This is totally a tool to extract better mileage from the vehicle.
There is no advantage as far as durability or anything else, it's all about mileage.


I would recommend against running the tranny through any shifts in the locked mode.
I have done this with a 700R4 and its bloody rough and if you get the mph a little too low the suckers will growl and chatter just like lugging a stick shift rig.

The very small clutch surface area in the converter was never designed to tollerate this stuff, again it was designed for cruising and not hard pulling.

Hope this helps.

My 87 6.2 with 700R4 locked the TCC in second gear right after the 1-2 shift. And it would stay locked no matter what the throttle position (it would unlock when acc pedal was released to idle). I bought the truck second hand, but I think the tranny was stock. You are right, it would growl and chatter going around the corner lugging in second gear. But now my brother still has this truck with over 200K miles, and the tranny hasn't been touched. Go figure.

I've also been playing around with this TCC lockup mod on my 95. Will have to see if I have the code 83, right now my 95 won't lock the TCC on its own with the the PCM. But I can lock it with the switch, so I really don't care. I have to check the wiring and make sure everything is okay. My manual TCC switch controls a relay to lock the TCC. I fed the switch from a wire on the brake switch, and added a switch to the accel. pedal. Now when either the brake is pressed or accel. pedal is released, the relay turns off and unlocks the TCC.

[rjwest]

Again, I will suggest removing power from the PCM for awhile,

I believe the driver circuits have way of shutting off the drivers that power things when they sense a short....

Did you just short the TCC to ground without cutting the TCC control line???

That would probably cause the code....

[ToddMeister]

Did you just short the TCC to ground without cutting the TCC control line???

That would probably cause the code....

No, I put in a SPDT relay. The common is connected to the TCC wire going to transmission. NC is connected to the PCM TCC wire, and the NO is connected to ground. With the relay off TCC should function like stock. The coil of the relay is controlled by the dash switch.

[Robyn]

Toddmeister

You may have a faulty TPS switch and or a Brake switch issue.

The other issue is there is also a possibility that a tranny shop did the checkball in the solenoid snout trick as I did. (BAD PLAN)

I would not do that again, and if I end up using the tranny from the Blazer in anything else I will remove the lockup gear and make the needed valving changes and install a non lockup converter.

The small loss of not having the TCC is no biggy. Having a converter that has bigger and stronger inner workings is a better way to fly.
The Non lockup units are built using some different parts that are far heavier and will last the long haul.

With the non lockup one can have a 4 speed that will live and no need for any wires to the sucker.

I have a friend that had me help him do his tranny and we did the non lockup converter and its wonderful.
Thing works so well its just nice and smooth with no issues and the sucker pulls better too.

The stator, turbine and pump are larger and this allows better power flow with less loss. Not to mention that the parts are soooooo much tougher.

[rjwest]

OK, 1 last try, did you forget to unlock the TCC when you came to a stop,

That may have disabled the TCC control line....

That is waht the BD torque Lock does, When speed drops to 30 MPH the
TCC relay that forces a lock up drops out..

[joed]

Thanks for the info on the code 83.

Just as Adam found, on my dad's 95, the code 83 seems to be there whether you use the switch to manually force lockup or not. I haven't tried disconnecting the batts. yet - but I have done the code clear by pressing both the brake and accel. pedals during diagnostic mode - it seems to work as it will start flashing a code 12 after about 10 secs. or so. Then 83 seems to come right back the next time it's driven.

The only wire I cut was the tan/brown wire at the trans. connector.

Sooner or later we'll get it...

Thanks. Joe.

[rabt]

Thanks for the info on the code 83.

Just as Adam found, on my dad's 95, the code 83 seems to be there whether you use the switch to manually force lockup or not. I haven't tried disconnecting the batts. yet - but I have done the code clear by pressing both the brake and accel. pedals during diagnostic mode - it seems to work as it will start flashing a code 12 after about 10 secs. or so. Then 83 seems to come right back the next time it's driven.

The only wire I cut was the tan/brown wire at the trans. connector.

Sooner or later we'll get it...

Thanks. Joe.


If You still have the Light in the switch hooked up, even though it doesn't work the PCM is gonna see that as a short circut and put the code up.

That is all a light bulb is a shorted circut.

[joed]

Hmmm, I don't think I have it wired that way - the light doesn't come on with the switch in either direction. Maybe I need to try a non-lighted switch?

Thanks. Joe.

[JohnC]

This may have already been covered, but...

When you turn the key to the first click, when the gear selector indicator light comes on, the PCM test the circuits for all the solenoids in the trans. If it doesn't like what it sees, it starts locking things out. My guess is the load on the TCC solenoid is not in spec and it simply locks it out. Why? You got me...

[joed]

I got a chance to work on dad's 95 today. Before I started it I checked codes - 83 stored of course. For the heck of it I tried unhooking the batts. for a few minutes to clear/reset the PCM. Once I did this, the TCC locked on it's own even with the trans temp below 140F and seemed to work fine after several more key on/off cycles. Plus it hasn't set a code 83.

So maybe, if you use the manual forced lock-up, the code 83 will set, and once it's stored the TCC won't work on it's own (at least until the trans is good and warm). Clearing the code by the depressing the brake pedal and accel. pedal at the same time trick doesn't seem to do it.

I hope this wasn't just a fluke. We'll see.

Joe.

[bcbigfoot]

I got a chance to work on dad's 95 today. Before I started it I checked codes - 83 stored of course. For the heck of it I tried unhooking the batts. for a few minutes to clear/reset the PCM. Once I did this, the TCC locked on it's own even with the trans temp below 140F and seemed to work fine after several more key on/off cycles. Plus it hasn't set a code 83.

So maybe, if you use the manual forced lock-up, the code 83 will set, and once it's stored the TCC won't work on it's own (at least until the trans is good and warm). Clearing the code by the depressing the brake pedal and accel. pedal at the same time trick doesn't seem to do it.

I hope this wasn't just a fluke. We'll see.

Joe.


This is how my truck operates, except there is no delayed lockup till warm issue even with the code 83 stored but my truck is a 93 and has no engine computer just a trans. controller/computer. I have talked to several other people that have done this mod with OBDI years of trucks they havn't mentioned a issue but perhaps they just havn't noticed it.

[rjwest]

Congradulations,,, If it was the driver circuit being locked out,
it was probably shorted to ground, OR,
left locked when coming to a stop, I believe there is a failsafe circuit...

[bcbigfoot]

OK, 1 last try, did you forget to unlock the TCC when you came to a stop,

That may have disabled the TCC control line....

That is waht the BD torque Lock does, When speed drops to 30 MPH the
TCC relay that forces a lock up drops out..



On my truck if I forget the lockup engaged coming to a stop, the lockup disengages when the truck goes into 1st from 2nd gear slowing down. Then when speeding up again 1st to 2nd gear shift is a little harsh because the lockup wants to engage at the same time as the shift.

[rjwest]

OK, I guess I do not understand how you forced the lock up.

If the sw is forcing the TCC locked, how does the PCM unlock it,
Or do you have a relay controlled by the shift signals...

Not questioning you , just trying to learn...

I have heard of the TCC lock up wired through a relay that was reset by the brake sw....

[bcbigfoot]

OK, I guess I do not understand how you forced the lock up.

If the sw is forcing the TCC locked, how does the PCM unlock it,
Or do you have a relay controlled by the shift signals...

Not questioning you , just trying to learn...

I have heard of the TCC lock up wired through a relay that was reset by the brake sw....


RJ, I had the same concern when i first installed the switch (or ground for the TCC lockup) that if I forgot to unlock the TCC at a stop light sometime it would kill the engine but after the first time I forgot to move switch back to factory setting I relized my concerns were unfounded. Perhaps there is a safty feature built into the 4l80e valve body or electrcally I'm not aware of, but the TCC drops out and will not lockup in 1st gear. I love my TCC switch, it still makes me grin decending 7% grades with a gross wieght of 9500lb and not needing brakes. Or climbing 7% grades and only having 180 degree trans temps, I usally back out of the throttle but still feel there is more hp hitting the ashpalt than when the converter is unlocked. The factory torque conveters seem like real hp pigs to me.

[atom_c]

I disconnected the batteries last night. This morning it locked after 2 miles and it was about 25 degrees out. Back to normal! I will have to see if it stays that way after using the switch again or if it starts throwing a code 83 again.

Adam