Cheap torque converter lockup kit project

[dclinton]

Ok guys, I’ve had a crazy idea to try and build a cheap torque converter lockup system for the NS using an Arduino to replicate the PWM signal the trans ECU sends to the TCC solenoid.

I don’t spose anyone knows the PWM frequency the ECU outputs? I’ve scoured the internet and can’t find any specific reference to it.

I can’t think of a way to figure it out without an oscilloscope, anyone got any ideas? I think it’ll be trial and error to get the right frequency where things stand at the moment.

If I can pull it off, I reckon it can be done with about $50 worth of bits from Jaycar. With the Arduino being easily programmed, I think there’d be a heap of scope to add functionality based on other inputs like vehicle speed, throttle input and gear selection.

[Ian H]

I'd think very carefully before you did that. I'm not a tech expert but seeing the amount of testing MM did in conjunction with OJ to produce his kit, it's not something which you can just build and plug in.

[dclinton]

What I plan on building won’t have any canbus functionality like the MM kit. I’m doing this out of necessity, the Mrs won’t approve the funds to buy a proper kit, so I’m having a crack at building my own. Lol.
Initially it’ll only be a simple on/off setup, but I might try adding to it after I get the basics working.

The ECU PWM signal prevents burning out the solenoid by switching the signal on and off rapidly instead of giving it constant 12v and also allows partial lockup by varying the duty cycle of the signal. The idea is to get the arduino to generate a 5v PWM signal that switches a mosfet to handle the full 12v of the car’s electrical system. After a ton of research, I’ve got a pretty good idea of how the system works, I just need to figure out the frequency.

[Ian H]

Good luck with it

[nj swb]

Pre MM, I developed my own basic kit for the Aisin transmission, and I expect the same process would work for the Jatco.

At a high level:

1. Looking at the circuit diagram, I identified the wires to the lock-up solenoid.
2. I cut the wires and installed in series a simple "power meter" that monitored both voltage and current, and hooked up a multimeter to check the frequency (it's a PWM circuit).
3. I went for a few drives under different conditions to make the lock-up activate, and recorded voltage & current being applied to the lock-up solenoid.
4. Then I designed & built a circuit that would
a. Apply to the solenoid the required voltage at approximately the right frequency, and
b. Apply a resistor to the output of the A/T ECU, to ensure the right current flows when the A/T ECU attempts to lock the converter while my circuit has it locked.

For the Aisin, I measured the PWM at 200Hz (using my multi-meter - nothing flash), but I didn't achieve that with my simple circuit. I only used a 555 Timer to do the PWM, and with standard values for resistors and capacitors (that I had on hand) it was either about 180Hz, or somewhere closer to 300Hz. I don't recall why the gap was so large, and I vaguely recall going with the lower frequency. I did have some issues with my final stage transistor overheating, until I realised it was conducting but not saturating - so dissipating too much power. A simple resistor change fixed that.

Yes, the NT factory programming includes a partial lockup that I didn't bother with, and I believe Marshall (m_and_m) found that later models don't do it. The factory system also ramps the PWM output, which I believe is primarily to provide smooth, unobtrusive lockup - I was more than happy to simply turn it on and off.

My lockup generated some occasional fault codes that seemed to happen if I switched my kit about the same time that the factory ECU was also attempting to lock or unlock. Not the end of the world.

The kit is still in my Paj, but not wired up - I got an offer on a lockup-mate that was too good to refuse.

Good luck.

[dclinton]

Pre MM, I developed my own basic kit for the Aisin transmission, and I expect the same process would work for the Jatco.



For the Aisin, I measured the PWM at 200Hz (using my multi-meter - nothing flash), but I didn't achieve that with my simple circuit. I only used a 555 Timer to do the PWM, and with standard values for resistors and capacitors (that I had on hand) it was either about 180Hz, or somewhere closer to 300Hz. I don't recall why the gap was so large, and I vaguely recall going with the lower frequency. I did have some issues with my final stage transistor overheating, until I realised it was conducting but not saturating - so dissipating too much power. A simple resistor change fixed that.

Yes, the NT factory programming includes a partial lockup that I didn't bother with, and I believe Marshall (m_and_m) found that later models don't do it. The factory system also ramps the PWM output, which I believe is primarily to provide smooth, unobtrusive lockup - I was more than happy to simply turn it on and off.

My lockup generated some occasional fault codes that seemed to happen if I switched my kit about the same time that the factory ECU was also attempting to lock or unlock. Not the end of the world.

The kit is still in my Paj, but not wired up - I got an offer on a lockup-mate that was too good to refuse.

Good luck.

Thanks mate, that's hugely helpful!! I don't spose you recall what sort of resistor you used to simulate the solenoid load?

[Dicko1]

This will be interesting. Hope it works for you...sometimes poverty is the mother of invention...lol

[Ky1e]

Interested to see how you go with this!! Will be following

[nj swb]

Thanks mate, that's hugely helpful!! I don't spose you recall what sort of resistor you used to simulate the solenoid load?

It was a 50W wire wound, don't recall the precise value - but you need to measure the current & voltage your Jatco solenoid is drawing, and choose a resistor value to suit.

Power dissipated is nowhere near 50W, but the bigger resistor will run cooler - I also mounted mine to a large piece of 3mm aluminium, to help dissipate the heat. It's under the carpet the passenger's footwell.

[dclinton]

This is how my Saturday has been spent. Prototyping and fiddling. Lol.
I think I’ve got the wiring pretty much sussed, onto programming the arduino and testing now.

[dclinton]

Have managed to get the PWM frequency outputting correctly. Working on being able to adjust the duty cycle/lockup amount by using the potentiometer on the control box. Pretty stoked with the way things are coming along at the moment, just waiting on the 100w 3.3 ohm resistor I ordered to show up before I can start testing on the car.

[cruisn06]

Great work mate

[chrisfarru]

Is the NS box same as the NM?

If yes, a mate gave me an instruction sheet with resistors and all to fit a TC lock up kit. I did it on my NM and it worked flawlessly.

[dclinton]

Is the NS box same as the NM?

If yes, a mate gave me an instruction sheet with resistors and all to fit a TC lock up kit. I did it on my NM and it worked flawlessly.

Any chance you can post it on here or send it to me mate?

[Kingmarz]

Is the NS box same as the NM?

If yes, a mate gave me an instruction sheet with resistors and all to fit a TC lock up kit. I did it on my NM and it worked flawlessly.

Please post instruction sheet on here it would be much appreciated.

Cos if you don’t I will private message you.