TCC current flow? How much is yours?

[Gnx6]

I'm having an issue with the Torque Converter clutch on my TR, before the mods move this thread I would like to add it is an ELECTRICAL concern, not mechanical...

When the car is cold and the tcc goes to lock it slips a lot. If I hit the manual lockup switch the converter locks properly. I think the driver (IC) is going out in my ECM. If you use a meter set on current flow, connect one end to terminal f on your DLC and the other to ground what do you read? Trying to find out if the solenoid is bad or computer. I think it is the ecm because when I drive the car as the day progresses it locks more firmly.

What is the current flow of your TCC?

Thanks!

 

[RmvBfrFlght]

Taking a slightly different approach, the resistance of a 700R4 TCC solenoid is 22 ohms (have a spare one).

Divide the voltage of 13.8 by 22 ohms is 627 mA. I know that some ECMs double up the quad-driver output to drive the TCC solenoid.

You can also measure the voltage at the pin F of the ALDL connector. When the ECM commands the TCC to lock it should drop to a little under 1 volt. This is based on a bipolar device saturation of .7 volts.

RemoveBeforeFlight

 

[salvageV6]

Make sure the ECM is grounded well, G120 back of head grounds it.

Make sure pin A7 in the ECM connector is clean and tight it's the ECM lockup ground output.

And there is a splice in the harness where the ALDL TCC wire joins the ECM TCC wire S807 that may be corroded in the harness just before going out the hole under the A/C box area pass. side.

Wiggling the harness may get it to work.

My car did that when I first got it in the winter time, used the ALDL wired switch and it worked fine.

Anything between .5 and 1 amp. would be okay on a meter for current.

Make sure the car is fully warmed up to over 120 or 140 degrees so the ECM will command lockup, I believe that is chip programmed.

It takes a bit of driving in under 20 degree temps. to get mine warmed up enough to get over 140 degree water temp. and command lockup from the ECM.

 

[Gnx6]

Taking a slightly different approach, the resistance of a 700R4 TCC solenoid is 22 ohms (have a spare one).

Divide the voltage of 13.8 by 22 ohms is 627 mA. I know that some ECMs double up the quad-driver output to drive the TCC solenoid.

You can also measure the voltage at the pin F of the ALDL connector. When the ECM commands the TCC to lock it should drop to a little under 1 volt. This is based on a bipolar device saturation of .7 volts.

RemoveBeforeFlight

Light bulbs and coils change resistance when energized. If you measure the current flow you will find it different than the calculations. I got schooled on that one a long time ago cause I used to calculated it the same. Try a simple test with a light bulb, you will se what I mean. Thanks for the resistance numbers though, also valid when looking for shorted or open coil.

 

[Gnx6]

Make sure the ECM is grounded well, G120 back of head grounds it.

Make sure pin A7 in the ECM connector is clean and tight it's the ECM lockup ground output.

And there is a splice in the harness where the ALDL TCC wire joins the ECM TCC wire S807 that may be corroded in the harness just before going out the hole under the A/C box area pass. side.

Wiggling the harness may get it to work.

My car did that when I first got it in the winter time, used the ALDL wired switch and it worked fine.

Anything between .5 and 1 amp. would be okay on a meter for current.

Make sure the car is fully warmed up to over 120 or 140 degrees so the ECM will command lockup, I believe that is chip programmed.

It takes a bit of driving in under 20 degree temps. to get mine warmed up enough to get over 140 degree water temp. and command lockup from the ECM.

Current measured was 439 mA at the ALDL.

I do have a caspers adapter harness for the GEN 2, maybe I will try grounding it at the ecm connector to see if current level changes. I know the ground at the heads is clean, I took it off and scrubbed that thing raw...

I will measure at ECM, thanks.. (Should have done that, just lazy)

 

[RmvBfrFlght]

Light bulbs and coils change resistance when energized. If you measure the current flow you will find it different than the calculations. I got schooled on that one a long time ago cause I used to calculated it the same. Try a simple test with a light bulb, you will se what I mean. Thanks for the resistance numbers though, also valid when looking for shorted or open coil.

Light bulbs change quite a bit in resistance when lit up. Coils/solenoids increase in resistance as they heat up, but not nearly as much as a light bulb (the light bulb is glowing hot, whereas the solenoid is not).

RemoveBeforeFlight

 

[salvageV6]

The solenoid is an inductive coil.

It's inrush/pull-in current is way higher than .5 A.

You need a scope to see that however since it's short lived.

Using the resistance measurement will get you in the ball park for holding current as proved here in testing.

An increase in wiring/connector resistance is probably more than likely the culprit, if in the warmer weather it locks up fine.

At least it was in my car.

 

[RmvBfrFlght]

The solenoid is an inductive coil.

It's inrush/pull-in current is way higher than .5 A.

There is no inrush current in an inductive coil. The current ramps up until it is limited by the resistance of the coil. Then when the current is cut off the coil responds with an inductive spike. Which is why there is a flyback diode integrated into the TCC solenoid.

RemoveBeforeFlight