Adjusting shift points and TC lockup

[Roger Jolley]

On second thought, perhaps a manually-activated paddle switch (located on the steering wheel) would be better suited for the task. And more esthetically pleasing.

[mechman600]

True, BUT....remember that it has to be simple/seamless so that my wife will not notice the difference. So automatically controlled it has to be.

[colonelk]

There is this programmable Auto box controller....

SSv4

that I believe can be used on any car with an electronically controlled auto. Not cheap though so would take a while to get back any savings you manage to get out of the MPG!

[Thymeclock]

It appears I am having the same problem with mine: click here

The up-shifts are observable for 1-2 (@15 MPH), and 2-3 (@ 25 MPH); 3-4 is murky at best, very hard to observe, with very little drop in RPM - then comes a big rpm drop at 45 MPH, presumably when the TC finally locks up. Slushbox indeed! But it's the TCM that controls the transaxle and makes it into slush!

My car is practically new, and as in your case, my wife drives it 99% of the time. I can't afford attempting tinkering with anything that might void the warranty.

[micondie]

Originally Posted by mechman600

Ok. I just had a good hard look at the Toyota shop manual, namely, the electronic transmission controls. It is controlled by the engine ECU, and there are 4 outputs: three shift solenoids and a TC lockup.

It would be nice to come up with an electronic gizmo that overrides the TC lockup output from the ECU. Here's what I'm thinking, using signals from the TPS and VSS:
If vehicle speed is above ~25 km/h and throttle position is below ~25%, my "device" triggers a relay that sends power to the TC lockup. If neither condition is met, the transmission acts normally.

You have to be careful with added circuitry to keep your ECU from getting strange signals and setting an error code. The check engine light would probably not brighten up your wifes day

[mechman600]

I did a bit of digging:
http://picasaweb.google.ca/lh/photo/...eat=directlink

It appears that the three shift solenoids are single wire solenoids, powered by the ECU and grounded internally. But the TC lockup solenoid has two wires to the ECU, so it is powered and grounded by the ECU. The question is, does it receive power all the time and get switched on the ground side, or does it receive a ground all the time and get switched on the power side? I will have to do some multimeter testing with a helper and a test drive.

this conundrum will only determine how I will eventually wire in the control relay. Once I figure out what the circuit does, I may just wire in a temporary switch that I can flip while I am driving to see if the transmission responds with any ridiculous actions, and to see what speed and throttle position I will trim the control device to.

And now the control device. Disclaimer: I barely know electronics. just the basics. Here is what I have come up with:
http://picasaweb.google.ca/lh/photo/...eat=directlink

Quite simply, I take a voltage from the VSS signal, through a diode for safely. When the output of the pot (adjusted for proper speed calibration) reaches the correct voltage against the zener diode, it opens and triggers the transistor to allow current flow to the TC lockup override relay. The same happens from the TPS signal with the two transistors in series so the two conditions must be met. The capacitor on the output is to smoothen out fluctuations from the VSS signal.

So, does this have the potential to work?

[Daox]

I'd check out this thread:

http://ecomodder.com/forum/showthrea...tch-10028.html

[mechman600]

Thanks for that link.

Huge design flaw in my first circuit. In the first one, the TC lockup overrides when TPS is above a certain value, not below a certain value. Here is the new one:
Picasa Web Albums - jamespvoth

[orange4boy]

There's a bunch of info in that thread Daox posted but we didn't get past a manual switch box. I like where you are going with this. I was hoping one of the electronics guys would chime in.

I still use my TCC switch now all the time in the van and it has been good for ~15% better FE. I do live in hilly country and that's where the biggest gains would be had.

Automatic manumatic would be sweet!

Subscribed!

[mechman600]

You're on Bowen Island, hey? I'm in Surrey. Trying to hypermile in the lower mainland is pretty much impossible because most people are simply just a-holes when it comes to driving. I guess that's another reason for going with the ecomod angle vs. the hypermile with what you got.

Electronics guy? Eep. Not quite. I know just enough to be dangerous. Very dangerous.

I read my Matrix shop manual a bunch today, focusing on transmission logic. The TC solenoid has one wire from the ECM that gets 12V when lockup is demanded, and grounds internally. There are 3 relevant fault codes that I am sure to run into:

1. P0741 - TC clutch performance: there is a turbine speed sensor that gets compared to engine speed to make sure the TC lockup clutch is working properly. The MIL will turn on if it thinks it is not locking when it wants lockup, or locking when it doesn't want lockup. Fortunately, this fault requires two driving cycles to trip, which may be enough grace to prevent the MIL from turning on with mixed highway/city driving.

2. P2769 - TC solenoid open, 3. P2770 - TC solenoid short. The solenoid should be between 11 and 15 ohms. However, P2769 will trip if goes above 100K ohms and P2770 below 8 ohms. That's a nice wide range, so I can add another relay and circuit with a resistor with a resistance of anything in between those to fool the ECM into thinking there is still a solenoid there. A small light bulb will be perfect.

I will have a diagram of this soon. Then, testing.