Auto trans tuning tips with TCI’s EZ-TCU

Words By: Dan Hodgdon

In today’s world, electronics play an important and useful role in nearly every aspect of the performance industry. Your hot rod or muscle car’s drivetrain is no exception. An electronic transmission control unit (TCU) allows for complete control over shift points, shift firmness, and shift speed when using a computer-controlled transmission. TCUs provide improved fuel economy, shift quality, and exponentially improved performance over the hydraulic-controlled transmissions of the old days.

But let’s face it, for many car guys, computers — and all those complicated wires — can be incredibly intimidating.

Luckily, Ashland, Mississippi’s TCI Automotive produces its own easy-to-install unit, aptly named the EZ-TCU. It is fully configured and ready to run out of the box.

We connected with TCI’s Will Vance to provide us with some insider info on how the system works, and how it’s actually much easier to set up than it might seem.

The kit includes the main ECU, a hand-held, the communication cable for the hand-held (or COM cable), a cigarette lighter plug-in that serves as the hand-held’s power cord, the main harness assembly, and the rpm module.

“There is a lot of harness, and a lot of times, that’s intimidating to a lot of guys who are unfamiliar with electronics,” Vance says. “But here’s the great thing; that’s the whole point of the EZ-TCU. We give you a lot of options.”

The following are a few of the most important elements when setting up the EZ-TCU.

Voltage

Vance is adamant voltage is key when dealing with a TCU, explaining you must have a good, strong battery producing 12 volts or better. The TCU comes with three wires: red, black, and pink. The red wire connects directly to the battery, while the black wire will connect directly to the battery ground. Meanwhile, the pink wire must go to a keyed hot wire, meaning anything that produces 12 volts or better when the key is in the run position.

TPS Signal

“A throttle position sensor signal is critical to the proper function of the TCU,” Vance says, noting it’s also important to utilize a 0-5 volt reference wire on any existing TPS.

“If you’re dealing with a fuel-injected motor, we give you a single wire so you don’t need the whole Weather Pack connector,” Vance adds. “All you need to do is splice into your 0-5 volt reference wire.”

If you don’t have an existing TPS, TCI offers a remote, plug-and-play TPS as well. Vance says whether you are using an existing or remote TPS, he has found the TCI system likes to see at least half a volt at the idle position with the key on. You can determine this by probing your wire with a volt meter.

“If your system breathes below [half a volt], we need to adjust your TPS preload to where the system will see half a volt or better,” Vance says.

Tach Signal

The EZ-TCU tach signal has two yellow wires. The reason for this has to do with the included rpm module. You’ll need this if you are running a GM HEI-style ignition (factory or aftermarket). “If it is a coil-and-cap design like an HEI, you must use the rpm module,” Vance warns. “It’s very critical.”

Wiring the rpm module is actually quite simple. Two wires pre-terminated to a ring will go to a good, solid ground. The white wire will be to the tach side of your distributor, and a yellow wire (male or female) simply plugs into whichever plug you have. However, if you are dealing with any other ignition besides the GM HEI coil and cap design, the rpm module is not needed.

“Either wire will supply what we need,” Vance says. “We simply need you to take one of these wires and tie it in to your existing tach lead signal. The reason we need this is because the TCU provides all base shift points on throttle position vs rpm vs speed.”

Output Shaft Speed Sensor and Case Connector

The wire labeled as “output shaft speed sensor” plugs directly into an existing GM speed sensor. TCI does not share this signal so it must be a sole plug-in. Finally, you’ll plug in the case connector and be ready to go.

According to Vance, “There’s always a question, ‘how do I know I’m plugged in right on the case connector?’ If you’ll notice, on your transmission, and on the harness itself, you have a keyway. This is designed to line you up so you ensure that you’re plugged in properly on any transmission you have with a TCU.”

Testing

The EZ-TCU hand-held provides a diagnostic screen to look at and make sure everything is connected and functioning properly. To communicate, simply take the gray COM cable that comes in the kit and plug it into the hand-held’s Weather Pack connector.

“These plug directly together; listen for the click to know you’re plugged in exactly right,” Vance says.
The other end plugs directly into the hand-held, and it’s always a good idea to run the screws down and anchor it so it doesn’t pull against the board. To supply power, you’ll use your cigarette lighter.

“Once we plug in our power cord we’re able to go to a live data screen where we’ll be able to retrieve information about the tach signal, the TPS signal, and a speedometer signal,” Vance says. “Those are your three key elements the TCU must see so that it operates properly in your application.”

Vance says he fields a lot of questions from street rodders who are confused and intimidated by computers and wires, but he is able to simply walk them, and all other builders and enthusiasts, through the process.

“As long as you can supply certain signals, this unit will function your transmission and allow you to adjust shifts, shifts, shift timing, shift aggression, lockup control, everything you want to control about it,” he says.

That makes the EZ-TCU a perfect tool for enthusiasts who like to tinker and be in control, but who also like to do things the easy way.

Source: TCI Auto, tciauto.com