Garage Series: A Much Needed 4L60E Transmission Controller Upgrade

sst-tciauto-leadartOne of the best decisions to make for a classic musclecar is to enhance your driving with upgrades to brakes and suspension, as well as an overdrive transmission. With the cost of fuel these days, a weekend cruise that adds a few miles can hurt the wallet a lot more than a few dollars. Having an overdrive transmission will lessen the impact at the pump by allowing you to make fewer visits.

When we upgraded Project Track Attack it was because, in addition to our regular weekend warrior trips to Willow Springs, we like driving the car on long trips. This old Plymouth has gone through a lot of changes the past couple of years, and it still sees over 5,000 miles each year, with some trips taking up to four hours to reach our destination. That’s why we reached out to Silver Sport Transmissions for a PerfectFit Transmission Kit – it gives us the performance we need at the track, as well as the better mileage on our road trips.


Our A41 PerfectFit Transmission kit from Silver Sport Transmissions. The kit is designed to fit cars built long before overdrive transmissions were available.

Electronically Controlled Transmission

Swapping to the electronically controlled 4L60E (A41 transmission) meant a few extra wires, and a transmission controller was part of the swap. While we did like some of the features of our previous transmission controller, we found that we were having some regular problems and there was not much in the way of support from the company that manufactured the controller.

TCI Automotive EZ-TCU

PN 302820

Transmission Controller

  • TCU
  • Harness
  • Handheld
    • Operates as electronic dash
    • Control shift points
    • Control shift firmness
    • Control shift speed
    • Control converter lockup
  • Can work with factory or aftermarket ignition, speedometer
  • Works with carburetor or EFI
  • Compatible w/ GM transmissions, including 4L60E, 4L65E, 4L80E, 4L85E & TCI 6x Six-Speed
Silver Sport makes the transmission packages to fit specific vehicles, but they are not a manufacturer of transmission controllers. Although Silver Sport is your first line of support for any issues regarding your PerfectFit Transmission Kit, the transmission controller is a big part of how your A41 performs.

When they changed to a new transmission controller, they looked no further than TCI Automotive. TCI Automotive builds its own transmissions, and also manufactures its own transmission controller specifically for electronically controlled GM transmissions.

Silver Sport now provides the TCI Automotive EZ-TCU (Transmission Control Unit) transmission controller with its A41 automatic PerfectFit kits. While there are just a few more wires for the EZ-TCU than our previous harness, it connects much in the same manner, and the harness swap was something that took just a couple of hours in the driveway.


We didn’t need a lift to get under the car; a couple of ramps and heavy-duty jacks stands did the job.

EZ-TCU Installation

We started by putting the car up on jack stands to get under it for the harness connections. We easily removed the previous harness entirely, and laid out our wires and searched for a place to mount the new TCU, making sure the harness could reach the transmission once plugged in.

We routed the new harness through a hole we had previously cut in the firewall, and ran it along the transmission and plugged in our two connections to the transmission: the main plug and the speedometer sender. This puts a majority of the harness inside the car along with the TCU.


There's a lot of wires and it can be intimidating, but all are labeled and it was a piece of cake. We were done in a very lazy afternoon, taking time out for some 'refreshments'. Two plugs on the trans, and we were done underneath the car.

The TCU can be mounted in the engine compartment, providing it is out of the way of direct heat sources and the elements. One thing that is very important with the TCU is the blue LED on the face of the module. With the TCU in the engine compartment, you don’t have any way of knowing if there’s an error code without checking through the handheld.

The LED will be lit solid if there are no issues, and will flash to indicate an error code. Therefore, we felt it was best to install the TCU inside the car to make it easier to monitor. While we don’t expect error codes to happen often, it just gives us peace of mind to know that checking at a glance is easier, especially while driving.


While it can be mounted in the engine compartment, we opted to mound the EZ-TCU TCU inside the car where it could be monitored.

TCI Auto’s Will Vance did give us some connection basics, as seen in the video above. Because the EZ-TCU works electronically, it requires input for speed, RPM, and throttle position in order to function properly. For those with a carburetor, TCI Auto offers a remote TPS that the harness can plug into. Because we already have a FAST EZ-EFI, we are able to utilize the FAST TPS wire for our signal. The new EZ-TCU harness provides a single hook up wire (white with a red tracer) for that connection.

There were just a few wires that needed to be connected to our existing harness to get the power going, and a set of connectors and a crimping tool from previous wiring jobs. Ron Francis Wiring once again proved to be a great asset to make secure wiring connections.

“My TCU is a little finicky about the TPS reading,” Vance said. “You should only need the white/ red wire from my harness connected to the 0-5V reference wire on the TPS of the FAST system.” Although ours was a bit shy of the recommended .5 volts at idle it was a simple fix, and Vance suggested making an adjustment on the FAST TPS to attain a minimum of .5 volts. (Note: If making this adjustment to the TPS, don’t forget to re-calibrate the TPS on both the EFI system and the EZ-TCU through the settings.)

My TCU is a little finicky about the TPS reading. You should only need the white/red stripe wire from my harness connected to the 0-5V reference wire on the TPS of the FAST system. -Will Vance, TCI Auto

The remaining connections are straightforward and simple: the pink wire connected to an ignition source, and power and ground connected directly to the battery. Two more connections are based on what you’ve got in the car: speedometer and tachometer. Since we have an aftermarket ignition system and Dakota Digital VHX gauges, we were able to connect these extra wires directly to the control box for our gauges.

The orange speedometer wire should only be connected to an aftermarket, electronically controlled speedometer. The yellow tachometer signal consists of a pair of wires split out of the harness to make the connection convenient. The female end can be plugged into the tachometer lead from a CD ignition box (never from the coil) and the male end plugs into the lead for the gauge. We simply cut our tach lead from the ignition and added the appropriate connectors so we could plug into the EZ-TCU harness.


Setting Up The EZ-TCU

Where the EZ-TCU excels is in all of its features, and that’s where we felt that this was an upgrade, as opposed to just a straight swap to a different controller. Our previous controller had a series of knobs used for adjusting shift points, shift firmness, and torque converter lockup. While turning a knob might seem to have been easier, there was very little understanding to these adjustments and how they functioned, and it got rather confusing because they weren’t consistent. Low throttle conditions required a very high setting, heavy throttle conditions required a low to medium setting.

Vance pointed out that the orange speedometer wire is not connected to the settings for tire diameter and gear ratio, which are for the Live Data portion of the handheld. “Speedometer setup for the PPM (Pulses Per Mile) setting is only in relation to the orange speed output wire. In other words, you can only change the signal going to the speedometer by choosing a different PPM setting,” he said. “Most companies will provide the reading that their sending unit is set up for if it’s not adjustable. Our unit is set to read from the trans at 4,000 PPM, which is standard GM design.”

With the EZ-TCU, the base settings are made through the setup screen by selecting specific parameters. TCI Auto has default settings that will get you back on the road, with just a few questions to answer with regards to engine, transmission, gear ratio, and tire diameter. The default settings can be modified to suit your driving style, and we’ve covered the setup and advance settings in another article to give a better understanding of what they mean, and how they will affect transmission functions.

Advanced features we’ve discussed include torque converter lockup and a performance mode, both of which are activated with a switch (not included in kit.) “The advanced features,” said Vance, “are there solely for the person wanting or needing to fine tune to shift preference, but are not required for normal operation.”

Base setup is simple, just a few questions about your vehicle, setting up the TPS, and saving the tune, and it's ready to go. Changes can be easily made to suit your preferences.

As with anything electronic, if you don’t keep up with the times you’re missing out, and Vance tells us that there are some upcoming features that we can expect. “We’re looking to add individual gear control as opposed to across the board changes,” he said. “We hope to also upgrade to the full-color touch screen [as used in the FAST EFI systems] in the near future.”

Final Verdict: Improved Transmission Control

Now that we have this transmission controller from TCI Automotive, we’ve been brought back to reality and now our transmission operates exactly as we expected it to in the first place. The transmission doesn’t shift too quickly into higher gears at low throttle like before, it shifts normally. Downshifting is now done automatically, unlike before where it was either a manual shift or romping on the skinny stick. This was a much welcome change to the A41 PerfectFit Kits from Silver Sport Transmissions.


It seemed that no matter how we adjusted the knobs on the prior control unit, it never allowed the transmission to work properly – there was always a trade-off. Now, it’s once again fun to drive the car in any situation: through the neighborhood, on the highway, and even when it’s time to show off a little. The TCI Auto EZ-TCU has made a night and day difference in how our Silver Sport A41 transmission operates, and that’s a great thing being that show season has just begun!

You can find your PerfectFit automatic transmission kits for many GM and Mopar classic cars at Silver Sport Transmissions. Silver Sport now supplies the EZ-TCU transmission controller from TCI Automotive with each of those A41 (GM overdrive) transmission kits.

Article Sources

About the author

Michael Harding

Michael is a Power Automedia contributor and automotive enthusiast who doesn’t discriminate. Although Mopar is in his blood, he loves any car that looks great and drives even faster.
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