The Free Mod Series: Part VIII Electronic Transmission Controller

[Toysrme]

Background:
Automatics are awesome. While the older automatics do a phenomenal job matching the shift pattern to the powerband when accelerating. You can find yourself wishing for a different gear at part throttle. Say flying through the entry of afew corners.
Low does fine for first gear. 2 can still downshift to 1st, and there is no way to hold third, or fourth. Annoying... So let's make this thing our bitch without spending hundreds on a transmission controller!
Theory:
If we can control the shift pattern. Our cars will have sex with us.
Instructions:

We'll need about $15-$20usd in basic electronic hardware.

• 1 6-position, double pole rotary switch
• 1 push button switch
• 1 DPDT Relay
• 3 15ohm 25 watt resistors
• 4 SPST Relays
• Around 10-15' of wiring (I used 20gauge)

For this example. We'll be using a 3vz-fe. For later transmissions, please check & understand that there may be an extra solenoid, or two that control other features. Most importantly the line-pressure. I wouldn't personally do this if your line-pressure is controlled by a solenoid instead of a throttle cable.

Shift Solenoid 1 = E10 (S1)
Shift Solenoid 2 = E9 (S2)
Torque Convertor Lock-Up Solenoid = E8 (SL)
Here is the shift pattern for S1 & S2 that derive the four gear ratios of the A540e transmission:

What we are going to do is change the wiring to the shift solenoids the control the gear selection (in drive) of the transmission. We are going to re-route the stock wiring through a DPDT relay (AKA Primary relay). When the relay is normally closed, they will pass the ECU signal as normal. When they are opened (powered). The relay will switch the circuit through a 15ohm 25 watt resistor to chassis ground. This will satisfy the stock ECU's desire to always see a 15ohm load from the solenoids.

From this point. The SPST relays (Secondary relays) will be spliced into the solenoid wiring AFTER the primary relay. When the relay is in the closed position, there will be no current to the solenoid. When the relay is tripped, it will supply the solenoid with current from a 12v supply from the common rail.
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For the torque convertor, we will splice one SPST relay(primary relay) onto the SL torque convertor lock-up. Normally Closed will pass the ECU signal as normal. Open will send the ECU's current through the remaining 15ohm 25watt resistor on it's way to chassis ground. Our last SPST relay (secondary relay) will connect as the others. Spliced in AFTER the previous relay. Open will connect a 12v supply from the common rail to the solenoid.
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I suggest the torque convertor secondary relay to be connected through a normal push-button switch, or toggle switch.
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The primary relay's coil supply should be put together & routed to the switch area. Route a wire from each of your secondary relay's coil to your switch area. You should have four wires. A line from S1, S2, SL, and the two first relays.
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Now for wiring our shift circuit!
Our 6-pole switch has 6 positions, and 14 connections. 2 connections will stand in the middle (Connect both of these together to a suitable 12v power supply.)
The remaining 12 connectors ring around the switch.
This is a double pole switch, so on any of our 6 positions, it will connect to two of the connectors. (Specifically, opposite sides.)

You can wire, to any way you wish. I chose:
Position 1 = Drive (normal ECU)
Position 2 = 1st gear
Position 3 = 2nd gear
Position 4 = 3rd gear
Position 5 = 4th gear
Position 6 = Drive (normal ECU)
To do this, from your starting position:

1. Empty, opposite empty
2. Connect to S1 (solenoid 1) and first relays, opposite empty
3. Connect to S1 and first relays, opposite connect to S2 (solenoid 2)
4. Connect to first relays, opposite connect to S2
5. Connect to first relays, opposite empty
6. Empty, opposite empty

You can obviously do your own variants. Such as one position holding a gear, and locking the convertor. I would keep it a separate function myself...
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Ta-da! We now have the ability to successfully bypass the stock control whenever we want, and select any gear we want (Including normal Automatic features), and at the same time controlling the torque converter lock-up how we want.
Anytime the 6-pole switch is in positions 2-5. The Primary relays will swap the ECU to see ground. And the secondary shift solenoids will be operated in the manner of gear selection. The Torque convertor will operate at-will of your switch.
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[nedm]

Theory:
If we can control the shift pattern. Our cars will have sex with us.

bahahahahaha best line ever

awesome right up as well. i think ive seen the same for the commonwhore auto's.

[Toysrme]

It's not like I'm the first person to do it. What generally stops Toyota/Lexus/Scion owners from doing it is the fact that even the old TCCU's check the resistance on the solenoid lines. If it reads open, or grounded when it shouldn't. It'll throw your O/D light & welcome you to some degree of limp-mode.

[timbosaurus]

Not knowing much about these 3VZ auto trans', I'd be concerned about the harshness of the shifts when manually controlled.

Normal shifts use PWM signals to "slow down" the shift so it feels half smooth. If you use this control i'm thinking you will get full line pressure shifting which wont be tolerable for too long.

Have you tried it yet?

Timbo

[Toysrme]

The faster & more pressure an A/T shifts with, the less slipping of the clutches, the less wear. In the case of any of the non-OBD-II cars with fully electronic transmissions. The valve body pressure is controlled by the gas pedal through the throttle-valve (kick-down cable). The more the valve is open, the higher the line pressure. The quicker & harder it shifts.
What I'm telling you. Is that the shift speed & harshness is no different than before.

Yes, I've been rolling it for alittlewhile. It's fine.

[timbosaurus]

cool. I've only experienced with later model trans' where line pressure is controlled by a valve body solenoid through PWM, not a kickdown cable.

Less wear on the clutches on the new 'boxes usually means more wear on the other driveline components.... and your back and your neck

But if the older toyota trans' control the pressure by the kickdown cable, then this sounds fine!

[Toysrme]

You could *probably* do it on the new ones. I've wired several non-toyota's to just ground the line pressure solenoid through a resistor to open the thing all the way.
Hey.... One of the world's fastest N/A v6 Maxima's this second is a stock automatic with this type of control (including the pw pressure solenoid) on a 3 position switch for gears 1-2-3.

[timbosaurus]

yeah, it would "work", and would be quick, and as a bonus would also save your clutch packs, but I don't know if it would be that bearable on the street

But as you said, if a car already has the mechanical kickdown cable regulating line pressure (I've never seen it, but I definately believe you), then it's all ok.

[thechuckster]

a neat use of this Mod would be paddles on the steering wheel

[Toysrme]

Who cares how it is on the street.. Let the computer hand it on the street sheesh LoL!
thechuckster that could easily be done for afe more dollars. Just add buttons that power a bi-directional rotary solenoid sitting on the rotary switch. Unfortunately, such solenoids here have not been used, or built in roughly 70 years?

[timbosaurus]

hehe... adapt those horn buttons found on cheapo wheels these days

[timbosaurus]

Who cares how it is on the street.. Let the computer hand it on the street sheesh LoL!

Good point

As much as I dislike auto's, I do like the idea of being able to switch it back to auto for the few times they are preferable

[thechuckster]

toysrme: i would't bother with an electro-mechanical thingo, i'd suggest driving relays with some logic - which would be triggered by momentary buttons/paddles on the wheel... i think kdog (on Performance Forums) used to sell a kit to do this kind of thing - it even included a readout telling you what gear you were in.

[Toysrme]

*or* for almost nothing. You can buy a rotary switch & have the exact same end result.
It's an amazing concept I know. hahahahahahahahahahahahaha

[sideshow]

why waste the fukin time spend the money and buy the tiptronic kit from kdog

i have 2 in stock if anyone wants they cost abit but are very simple and smart

its much easier to use kdogs tranmisson controller i have one on my car
and ive used a 2 channel remote control to send signal from buttons on wheel to goto unit so no cables used but ive disconnected it for now till i tidy it up

i recently got my auto tricked up too by a place in sydney

it fukin rocks now

medium throttle and it has nice small chirp into 2nd

no lag between gears now feels like small nudge in the back each gear change

soon ill hook up the triptronic buttons and see how much better it is