Black CTS-V: Disable CAGS

Black CTS-V:
Disable CAGS

Computer aided gear selection (CAGS) is a hack invented to avoid the gas guzzler tax. A solenoid is used to lock out second and third gears when the following conditions are met:

Engine coolant 171° F or greater
Speed between 15 and 19 MPH
Throttle position is 13% or less

During the lockout, a dashboard light that says "1 → 4" is illuminated and you are supposed to shift from 1st directly to 4th. There is no timeout; that is, the lockout continues as long as the above conditions persist.

My first encounter with CAGS was the 2000 Camaro SS I had. The skip shift eliminator kits sold available back then used a flawed design. Since the CAGS solenoid measured 120 Ω, they built a harness that connected a 120 Ω, ½ watt resistor to the ECM. While this worked, at 13.7 volts this works out to 571 mA or 7.8 watts. That's a lot of power to run through a ½ watt resistor. There was some potting compound but I eventually noticed that my bypass had melted a bit.

Since the ECM considers a modest current draw sufficient my stragegy for disabling CAGS in my CTS-V was to put a resistor in series with the CAGS solenoid. For one thing it means you don't need to ty-rap the loose end. Also you don't need a dust/water cap for the solenoid connector.

I built my cable with a ¼ watt, 20K Ω resistor and 20AWG wire (Belden 83027 TFE jacket):


20K Ω resistor	!CAGS Cable

The factory service manual (volume 4, page 11-814) shows the skip shift solenoid actuator is connector Q34 with pin A (gray) as the switched (ground) skip shift signal and pin B (pink/black) as the battery positive voltage.

Here's a parts list for the wiring harness:

Quanity Delphi Mouser Description

1 12162000 829-12162000 Metri-Pack 150 sealed 2-way connetor (male)

2 12045773 829-12045773 Metri-Pack 150 male pin (2.78 to 1.69mm)

1 12052646 829-12052646 Metri-Pack 150 sealed 2-way connetor (female)

2 12048074 829-12048074 Metri-Pack 150 female pin (2.80 to 2.03mm)

4 15393249 829-15393249 Metri-Pack 150 green cable seal (1.6 to 2.15mm)

2 12052634 829-12052634 Metri-Pack 150 wire TPA (blue)

Quanity	Delphi	Mouser	Description
1	12162000	829-12162000	Metri-Pack 150 sealed 2-way connetor (male)
2	12045773	829-12045773	Metri-Pack 150 male pin (2.78 to 1.69mm)
1	12052646	829-12052646	Metri-Pack 150 sealed 2-way connetor (female)
2	12048074	829-12048074	Metri-Pack 150 female pin (2.80 to 2.03mm)
4	15393249	829-15393249	Metri-Pack 150 green cable seal (1.6 to 2.15mm)
2	12052634	829-12052634	Metri-Pack 150 wire TPA (blue)

The inline Delphi connector that mates with the factory harness is not available. 12162000 is very close but has a key that needs to be removed:

The left connector is unmodified and the right has the key removed.

Other Skip Shift Disable Methods

Here are some other skip shift delete methods:

Radio Shack: Disconnect the skip shift solenoid connector at the transmission and jam a resistor into the wiring harness; optionally wrap with black electrical tape.
Programming: Another way to disable CAGS is to use a programmer such as EFILive's FlashScan. There are several ways to do this; for example you can lower the maximum throttle position to 0.0% or raise the minimum temperature to 600° F.
Denial: By far the cheapest and easiest method, all you need to do is claim that the way you drive your car, CAGS never kicks in!