Tech Thursday: C5 CAGS

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Transmission CAGS
What is CAGS?

To avoid a gas guzzler tax, Chevrolet invented a skip-shift device on its manual transmission cars called Computer-Aided Gear Selection, or CAGS. CAGS forces you to shift your manual Vette from first to fourth (rather than second or third) when:

  1. Engine temp is greater than 169 F
  2. Vehicle speed is 15 – 19 mph.
  3. Throttle is open 21% or less.

Under more spirited acceleration CAGS does not interfere, however.

Can CAGS be eliminated?

It sure is annoying and I’m afraid to drive my Vette too fast, can I just get rid of it? Yes, there are four ways. First, you can simply accelerate harder. Second, you can replace the fuse that allows power to flow to the system with a hacked fuse, but this can cause error codes to pop up. Third, you can buy a skip-shift eliminator kit and either DIY, or have it installed and finally you can reprogram the car’s computer so that the parameters for CAGS to work are outside the normal spectrum (ie set CAGS activation temperature to 500*F).

Let CF member Bugman guide through the following CAGS skip-shift elimination install:

First, jack the car up safely. If you’re not familiar with how to jack up the C5, read the Jack page first. BE CAREFUL!!! If the heavier-than-you Vette falls on top of you, it’ll be a closed casket service for sure. If you don’t feel you can very, very securely raise the car, don’t do this — take the bypass kit to your mechanic who can do it on a lift instead.

When the car’s engine/exhaust are cold, you’ll have to slide under the car about 4 feet from the rear of the car, until your mid-thighs are about touching the end of the driver’s side tail pipes.

All the action here is on the DRIVER’s side of center, so you will want to slide in from the rear, on the DRIVER’s side. You won’t be able to reach what you need if you approach from the passenger side.

Step 1: Use a flashlight, and look up until you see this big silver thing with the “DEXRON III” sticker on it — you can’t miss it. This is the transmission.

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Step 2: On the left (driver’s side) of the transmission, you’ll look for a wiring harness covered in a black plastic loom. At the end of that harness you’ll find a blue/white plastic locking clip. This is what you’ll unplug to do the “CAGS bypass”.

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Step 3: This is just a white plastic clip. To disconnect this, you’ll have to use two hands. With one hand, pull the white clip outward, while with the other hand you pull on the blue piece to unplug it from the transmission.

This picture shows the wiring harness now unclipped from the transmission. I have just pulled the blue connector (*) from the copper colored connector (*) on the transmission.

The + marks a nice convenient place where you can run a zip tie to secure your wiring later, so that it does not contact the exhaust and melt.

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Step 4: Your CAGS bypass kit should contain a new blue plastic plug. Take this and plug it into the copper-colored connector on the transmission.

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Step 5: Your CAGS bypass kit will also contain a longer black “bypass harness”. Plug this into the Corvette’s wiring harness, which you left dangling previously. Just plug it in until it clicks into place and is nice and tight.

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Step 6: Now just wrap one or two zip ties around your CAGS wiring harness, and secure the whole mess to the little tab on the transmission, so that your wiring will not stray over and touch the hot exhuast pipe only a few inches away.

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You’re done! Now go test it out and reward yourself with a nice cold beverage… Thanks Bugman!