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4L60E Transmission Control Unit - Electronically SpeakingTCI’s Transmission Control Unit Lets Our Crossfire Z Fly By Wire. From the June, 2009 issue of Camaro Performers By Joe Rode Photography by Joe Rode
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The first thing we did was... The first thing we did was unravel the massive, and somewhat intimidating, wiring harness (PN 377502 $146.95) pictured here with the TCU. Don’t be too nervous, all connections are clearly labeled. It’s a good idea to read through the instructions completely (they’re not that long and are easy to understand) and get familiar with the various connectors. •Previously, we took you through the necessary steps for installing a modern electronically-shifted 4L60E trans into your third-gen. But we only got you half way there. This month we made a trip over to Westech Performance in Mira Loma, California, where their electronics guru, Ernie Mena helped us put the brains behind the brawn and added a TCI electronic Transmission Control Unit (TCU) (PN 377500l, $774.38). The introduction of electronically-controlled transmissions which use a computer to tell the trans when, where, and how to shift, has done wonders for the performance and durability of GM overdrive units. And with a computer calling the shots, you won’t have to deal with the frustration of having your trans shift into overdrive too early or too late. TCI has gone to the next level by giving the end user the opportunity to custom tune their trans by using a simple software interface and personal computer (TCI has recently released a stand alone data logger that allows you to do the programming once the TCU has been initially setup with your computer). After following a simple step-by-step setup wizard, the TCU program allows you to modify numerous aspects of your transmission's behavior with a laptop computer, including converter lock-up, shift points, and line pressure. The majority of this installation involves wiring and computer input, so if you’re not comfortable with crimping and cutting, or basic PC functions, it may be best to leave this install to a professional.  Next, we had to find a secure...  Next, we had to find a secure place to mount the TCU. The unit is weatherproof, so you can mount it in the engine compartment. This is not a likely option if you’re dealing with a late-model emissions car like our ’83 as there’s barely enough room for all the junk that is already in there.  After considering several...  After considering several possibilities, including under the passenger seat, Westech’s wiring technician, Ernie Mena, came up with the idea of piggy-backing the TCU onto the stock ECM. We removed the front seat to open up our work area.  The TCU harness should be...  The TCU harness should be long enough to accommodate most placement positions. Once we double-checked that there was adequate length to reach all of the connection points, Ernie got things organized with some electrical tape. TCI strongly recommends that you don’t splice or modify the harness for any reason.  With our mounting location...  With our mounting location determined, we needed to get the harness through the floor to its connector on the transmission. We found a spot beneath the shift console on the passenger side that would be out of sight and not interfere with the seat mounting. After drilling a pilot hole from inside the car, we used a hole saw from underneath to cut an opening big enough for the main connector.  We then connected the main...  We then connected the main connector and the Output Speed Sensor (TOSS/VSS) located in the tailhousing of the transmission. The TCU uses the VSS output to calculate road speed.  To make the TCU “go,” you...  To make the TCU “go,” you will need power from a source that turns on with the ignition, a ground, an RPM signal from the distributor, and a signal from the throttle position sensor (TPS). Ernie took a bit of a short cut and, with the help of a wiring diagram downloaded from www.autozone.com, he tapped into the stock wiring harness for all but the ground wire. This connection needs to go directly to the battery to reduce the amount of electrical noise to the TCU.  With the harness buttoned...  With the harness buttoned up on the underside, we routed the inside portion under the carpet towards the dash where the TCU would be mounted.  The harness has to be protected...  The harness has to be protected from the sharp and jagged edges of the sheetmetal we just drilled through. Ernie used a grommet left over from a previous project. A similar item can be found at your local hardware store or online at McMaster-Carr (www.mcmaster.com).  These are the connectors we...  These are the connectors we used to tap into the harness. It saved us from going through the firewall and making connections in the engine compartment.  In order to determine the...  In order to determine the proper shift points and firmness, the TCU needs to know the throttle position at all times. On vehicles not equipped with a TPS, TCI offers a remote-mount TPS (PN 377401 $152.60). To make things easy under the hood, they also have available a Distributor Adapter Harness (PN 377100 $51.80) and TPS Adapter Harness (PN 377201 $80.40) that hooks the TCU connectors into your existing GM harness.  The end of the harness plugs...  The end of the harness plugs into the TCU and then locks into place with a twist. You can see the stock ECM to the right.  With everything connected,...  With everything connected, but before its all buttoned up for good, we manned the throttle pedal while Ernie used his laptop to verify that the TPS signal was present.  On the driver side of the...  On the driver side of the car, the torque converter lock-up release switch (gray wire) gets connected to the positive brake light wire. This unlocks the converter when the brakes are applied for smoother operation during deceleration. After putting the ECM and TCU back under the dash, we were left with just the 5-foot long communication cable which allows the TCU to interface with a laptop.  To make things even simpler,...  To make things even simpler, TCI recently introduced their new Touch Screen Dash/Data Logger (PN 377525 $793.75). Not only does it allow you to touch-tune your automatic transmission’s operation through the TCU, the Dash/Data logger monitors and logs data from other engine management systems. With the LCD screen, it can display data in multiple ways, such as scales, units, and gauge configurations.  With the baseline program...  With the baseline program uploaded to the TCU, we strapped our Camaro to the dyno for fine tuning. This pre-loaded calibration works well in most performance applications. The beauty of the TCI system is that you can tailor your transmission’s performance to your preferences of how hard, and when you want it to shift. The software files include complete instructions on customizing your program.  The TCU offers the ability...  The TCU offers the ability to manually shift the trans via an electrical switch. The paddle shifters are ideal and simply plug into the harness. It also has the ability to store two separate programs that can be selected by an externally-mounted switch. For example, one soft shifting program for commuting, and one to unleash a neck-snapping strip tune. You also have the option of turning off your overdrive all together, or locking and unlocking your converter.  We used the ever-versatile...  We used the ever-versatile double-sided Velcro to secure the TCU to the stock ECM.
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