AW4 Governor / Shift Kit

Difficulty 2/51–3 hrs$30–1201987-1990, 1991-1995, 1996, 1997-2001

The AW4 doesn't use a mechanical governor — shift points are TCU-controlled. 'Shift kit' on this trans means valve body modifications (see valvebody entry).

Unlike older 3-speed autos with mechanical governors, the AW4 uses electronic shift control. Shift points are set by the TCU based on vehicle speed (VSS), throttle position (TPS), and shift mode (Power/Comfort).

What 'shift kit' means on an AW4 is valve body modification — see trans-aw4-valvebody for that.

What you can change electronically:

Power/Comfort button: stock feature, holds gears longer in Power mode. Use it.
TPS adjustment: a worn TPS causes the TCU to misread throttle and shift wrong. Adjust per FSM, replace if voltage sweep is noisy.
VSS calibration: bigger tires shift the speed signal. Either change the speedo gear in the t-case to match new tire size, or fit an SGI-5 calibrator that scales the VSS signal in real time. SGI-5 (~$80) restores correct shift points after a tire/gear change.
TCU swap: some 96-01 TCUs have slightly different schedules. Mostly noise; the SGI fix is the real one.

If you have 33s+ and never recalibrated, your AW4 is shifting too late and probably annoying you. Recalibrating the VSS often makes the trans 'feel' fixed with no actual rebuild.

Why it works

restores correct shifts
cheap

Trade-offs

doesn't change shift feel
different from old-school shift kit

Tools required

multimeter
socket set

Parts

Part	Vendor	Est. price
SGI-5 speedometer/VSS calibrator	Hypertech/Yukon	~$80
T-case speedo gear	Novak	~$25

Sources

{'title': 'VSS calibration discussion', 'url': 'https://www.cherokeeforum.com/f2/vss-calibration/'}

Written and maintained by an AZ wheeler and driveway wrencher. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.