CompuShift Plus - Take Control of Your
thru 2001 Cherokees and the 1993 Grand Cherokee utilizing the AW4
automatic transmission with first and second gear combined in one
position. This review specifically targets the 1996 and later XJ
Cherokee, however it also applies to other Jeeps utilizing the same
transmission configuration. The post 1996 vehicles are of particular
interest as there have been some questions raised as to
compatibility with the CompuShift Plus. It is the writers
understanding that units are available for Cherokees back to 1987.
"The most exciting aftermarket performance
enhancing product to come along for the Jeep Cherokee,
especially for you guys who are totally frustrated with the
combined '1-2' shift position in your automatic
The Jeep Cherokee XJ is, with out a doubt, one of
the best all around 4x4s available. (This opinion is based on the
authors forty plus years of four wheeling and the ownership of 14
different 4x4 vehicles.) Unfortunately it is no longer in
production. The vehicle does, however have one major fault. The
automatic transmission has only one detent for both first and second
gears. This means that there is no way to hold it in second gear
when coming down a grade. It automatically downshifts to first when
the vehicle drops below about thirty miles per hour in high range or
below about ten miles per hour in low range.
The CompuShift Plus has been largely marketed as a
device to keep the AW4 transmission from downshifting unexpectedly
while driving in slippery conditions and causing the vehicle to spin
out of control. This attribute is certainly of value, however it is
the author's contention that the CompuShift Plus has much more than
this to offer the serious 4x4 enthusiast.
Anyone who has done much four wheeling knows that
second gear in low range is great for descending moderately steep
trails and also for climbing hills with limited traction and speed
is desired. It is very disconcerting to slow up for a water bar or
other obstacle and have the transmission slam into low gear.
CompuShift Plus has the magic answer! A simple
toggle switch allows one to manually select and hold the
transmission in second gear. It is now possible to downshift from
third to second gear and slow to a complete stop with out
automatically downshifting to low. You can also start in second when
conditions are very slippery. The transmission shifts smoothly from
low to second and back again by merely flipping the switch.
It should be noted, however, that the CompuShift
Plus is much more than just a switch. It is a patented device that
takes over from the stock transmission control unit. It
automatically switches back to the normal configuration once the
shift lever is moved out of the 1/2 position. The stock transmission
control unit remains intact and if a CompuShift Plus failure should
occur everything reverts to the original shifting mode.
Yes, it is possible to control shifting with
switches, as some have advocated, but this approach has a number of
problems and is not a viable solution for most users. The CompuShift
Plus overcomes these problems.
See Step 1
See Step 2
See Step 3
The CompuShift Plus can be installed in 15 to 30
minutes with only a screwdriver, a pair of pliers and a drill. It
comes nicely packaged with everything needed except for a good way
to attach the small computer box. I used some industrial-quality
Velcro, although one could fasten it in place with wire ties. The
computer module is nicely constructed and appears to be quite stout.
It is reportedly “water-tight”.
1. The first step is to locate the transmission
control module, which is found under the dash. In the 1997
Cherokee the module is located above, and to the right of, the gas
pedal. (It is the authors understanding that some vehicles have it
located on the passenger side.) It is now very simple to unplug
the wiring harness and proceed with the installation.
2. The next step is to unwrap about four inches
of tape from the wiring harness. All of the wires are color-coded
and the plug is numbered so it is easy to find the proper wires.
The manual has excellent instructions as to what to look for.
3. Next, after locating the correct wires, the
CompuShift module is wired into the harness. This is accomplished
by slipping a splicing connector over each of the seven existing
wires, inserting a CompuShift wire, squeezing the connecting clip
with a pair of pliers and then closing a protecting flap. This is
the only tricky part as there is not much space under the steering
wheel to work and the length of the wires between the firewall and
the harness connector is only about six inches. Make sure to seat
the CompuShift wire all the way into the splicing connector and
hold it tightly in place when squeezing the connector clip,
otherwise it will back out and you will only be connected to the
harness wire. This could damage the harness wire and although it
could be fixed, the installation process would certainly be
slowed. One method to facilitate this step is to tape the wires
together prior to squeezing the connector.
4. The next step is to locate a position for the
switch. The writer located it on the dash, above and to the left,
of the shift lever. You need to drill two holes for mounting the
switch bracket. This bracket should be attached using two
self-tapping screws. Some users may want to replace the switch
with a higher quality switch and mounting plate.
5. The last step is to fasten the CompuShift box
in place and tie up the wires with the provided wire ties. The
author used industrial strength Velcro to fasten the unit under
the dash as noted above (not included).
After the installation is complete the unit is
tested according to the simple instructions in the manual. A red
indicator light will come on when the unit is activated if all of
the wires have been connected properly. The final step is to road
test the CompuShift Plus according to included instructions.
Testing: Click Here For
Part 2 ~
Dirt Road Magazine is sponsored by Turner 4WD Parts Co.