I made this circuit to control the Torque Converter lock-up solenoid. I use it for towing the caravan.
The Switch locks the torque converter ON.
Green LED indicates the torque converter locked up. (When either the ECC unit turns it on or you turn it on via switch)
Red LED indicates the torque converter locked up but the ECC unit has not locked it up, in other words, switch has locked it up.
To see it in operation, drive along and when you hit 60 or so the green light comes on. This means ECC has switched on lock-up.
Switch on the switch. No change in LED’s, as the switch has not really done anything yet.
Accelerate strongly, or decelerate, and the RED LED will come on, indicating that the ECC has tried to disengage lockup, but switch has overridden it.
I’ve noticed some interesting things…
Even with 12v on the lock-up solenoid, it WILL NEVER LOCK UP IN 1st or 2ND gear.
So if you switch on lockup while stationary in drive, it does not stall. Then start to drive, TC only engages when the engine hits 3rd gear. If you now brake, it stays in 3rd gear and the engine will shudder and stall if you stop as TC is locked up in 3rd gear at low speed.
Here’s how my circuit works.
Switch in up position = normal driving mode.
There is no change to the car wiring. The green LED comes on to indicate when the torque converter is locked up. It is interesting to watch, the torque converter comes on at 45 k/h when the car is in drive or 3rd gear in economy mode.
Switch in down position = torque converter manual lock-up.
In this position the torque converter relay is is connected to 12V, thus switched on. The green LED comes on to indicate this.
THe red LED only comes on when the ECC module has switched the lock-up off, but the switch is forcing it to be on. This is a reminder that you are over-riding the ECC setting.
ECC connects to the Lock up Solenoid (Solenoid 7) wire. It comes out of pin 96 of the ECC unit which is in the passenger side near their feet. Far better to take the top cover off the ECC and look at what color pin 96 wire is, then break this wire about 1 foot further along where there is more room, under the glove box. On my EL falcon it is a light blue wire, but there are two light blue wires, hence the need to trace it from pin 96.
12 volts power can be found at the wire coming out of pin 71 or pin 97 of the ECC unit.
and the ground can be taken from pins 103 or 76 or 77 or 51.
I mounted the two LED’s up on the dash, just above the switch, then ran wires down to below the glove box.