Light when Torque Converter locked

[DWillenbring]

I've been trying to hook up a light to come on when the Torque Converter is locked. I'm certainly doing something wrong and thought that someone out there could help me out. Which wire (and where?) am I supposed to be looking for on which to tap into for the light?

 

[Joe G.]

Actually, there is no way to wire up a light to show that. What happens is that the lock up solenoid is activated electrically. Then IF the hydraulic conditions are correct (sufficient pressure) then the torque convertor clutch will lock. So you can wire it so that a light will indicate that the lock up solenoid is in the lock up state, but the TCC may not in fact be locked.

 

[DWillenbring]

Thanks, Joe. Back to the drawing board. The fun for me is in the seeking. I came, I sought, I conked.

 

[illflem]

If you are an electronics wiz you could tap into the input signals to your tach and speedometer when the correct combination occurs the light will come on. Otherwise you can just watch your tach and speed to tell when locked up, but that's not as fun.

 

[bdaniel]

Actually I have done this in on my truck. I have the Banks GIT Kit which defuels during TC lockup. There is a wire that hooks to I think wire number 12 on the middle ECM plug on the passenger side under the hood. I got a low current LED from Radio Shack (About 15 millamps if I recall) and mounted the LED in my A pillar near one of the guages. I have mine set up to glow when the TC is unlocked and to go off when it is locked up.



I'm giving these details from memory because I did this a year ago and it has worked fine ever since. I like having it.



I have noticed that while in 3rd unlocked, the LED will go out and there is about a 3/4 second delay before the TC locks up. This is the hydraulics doing it's thing as someone earlier pointed out.



The shift from 3rd lockup to OD unlock to OD lockup is much quicker. The TC unlocks very briefly during the 3rd to OD shift. It is just a quick flash of the LED.



Hope this helps.

 

[azgearpro]

light

Bill kondolay sells a torque convertor saver, that unlocks the convertor under adjusted throttle, and has the light which shows when you enter lockup and anouther light idicates when you are out of lockup.

 

[Strick-9]

DWillenbring,



You should be able to wire this circuit just like you planned.



When the TC lock up solenoid recieves a ground, it immediately forces the switch valve in the valve body to cycle. Once this has occured, the TC will lockup. According to TCRA, torque converter rebuilder's association, if the switch valve cycles and the TC doesn't lock then you have a problem with your TC and it should be replaced.



So basically, if your converter is working properly, this circuit will work fine. Actually, an LED is often added to the circuit for testing purposes to better diagnose problems.



-Chris

 

[Joe G.]

Chris,



Not always. If your throttle is at idle and the solenoid receives a ground the TC will NOT lock! This is important if you are using an exhaust brake which depends on a locked TC to do the job. In this case you have to give it a little throttle to cause it to lock. Not what you really want to do on a steep downhill with heavy trailer in tow. I had a couple of scary experiences before I figured that out.

 

[DWillenbring]

Strick-9 et al: I'm still in a quandry as to which circuit you are referring to and where I can find it.

 

[Joe G.]

My truck is a '95 so the wiring diagram has probably changed quite a bit for your '99. If you have the service manual go to the transmission control diagram and find the lockup solenoid. There should be 12 volts constant on one side and a wire to the computer on the other. The computer puts a gound on that wire to energize the solenoid. My transmission is a 47RH while yours is a 47RE so I can't help you much here with the exact wire color.

 

[Strick-9]

Joe,

Your lockup solenoid doesn't receive a ground while the throttle is at idle. That's why you have to apply throttle to get your exhaust brake to work. Part of the friendly PCM calibration.



But I know you've been around a while. Maybe I'm misunderstanding you. Are you saying even with a mystery switch, it won't lock under decelleration? If so, this may help me with something I've been working on lately.



DWillenbring,

I have a '98 service manual. Not sure if the wires are the same for yours or not. TC solenoid control should be Orange with a Black tracer. If memory serves me correctly, once the truck starts the wire should be non-grounded (+12V maybe?). When the TC is commanded to lock, it should be grounded.



Wire your light with +12V to one side and connect the other side to this wire.



Good luck,

Chris

 

[Joe G.]

Chris,



That's right. I'm talking about a manual switch that forces a ground on the solenoid. The CPM removing the ground at idle is the reason for the so-called mystery switch in the first place. If you forget to lock the TCC with the switch before you lift then it won't lock if you ground it later. So if you have a light rigged to show when the ground is on the solenoid to indicate that the TCC is locked it's telling a lie in this situation. The bad part is that when you want to use an exhaust brake is exactly when you want to know if the TCC is locked or not. Otherwise, knowing that it is locked or not is just idle curiosity. I don't know how the TCC lockup works internally, but once it's locked it will stay that way even to the point of killing the engine if the ground is not removed. I scart me widdle self once on SR299 before I figured that out. Steep crooked grade and I flipped the switch to lock up. Took off down the hill like a run away freight train! Hit the brakes and the throttle to lock it. Didn't lock. Not enuff throttle! The first turn was a LOT of fun! I've experimented with it some and found out that the truck has to be pulling or accelerating to cause a lock up. Just more throttle won't do it.

 

[DWillenbring]

Thanks! I appreciate the help. Yes, I have a '99 service manual and that's the same thing it says. My problem has been that I've been trying to hook up to the TC wire and grounding the other end. Zounds! Don't think I would have figured that out by myself. You guys is genii.

Dave

 

[Snow man]

Go ahead and wire it up,the only convertor that wont lock under heavy throttle that im aware of is the DTT. My DTT will not lock up under a load,even with the forced mystery switch on,the stock tc would lock up instantly,no mtter what.

 

[DWillenbring]

I got the light working, in fact have two of them; one running thru the regular circuits and another thru my BD Autoloc/PacBrake. It's quite informative to watch them working. I can watch the effect of the PacBrake vs the normal system. I'm setting them up as Port and Starboard lights on my dash.



At the same time the Check Engine light is now a frequent visitor. Does anyone know if I need some kind of resistor or other inline electronic wizardry?