Intro
The ACE LS swap uses the factory transmission controller in the Discovery 2. This works good for people wanting a straightforward option. However, the transmission shift profiles are programmed for the Land Rover 4.0 or 4.6, and are not customizable. If your Disco has bigger tires or a performance LS to get the most out of it the transmission, it needs a tunable controller .

Enter the HGM Compushift.

The Compushift is a standalone controller that allows you to change virtually all aspects of the shifting of the electrically-controlled 4HP22 and 4HP24 in the Discovery 2. You can change shift points and shift pressure. It’s controlled through either an optional display or an app on your phone. It’s a slick setup, and you don’t have to be super experienced to figure out how to use it either.



The package that comes from Compushift includes the controller and a harness with the plugs to plug directly into the main plug onto the 4HP22/24 with a couple of additional splices.

Here is where the issue is though. Compushift is basically a plug-and-play setup that could be used with any car. Meaning that to use the Compushift, you have to unplug the wires from the 4HP22/24 to the Discovery … and the Discovery’s BCU etc. does not like that. The transmission wiring ties into loads of features in the D2 — from the rear windshield wiper to the SLABS.

Furthermore, the Compushift cannot be simply spliced into the Discovery’s wiring because the Compushift runs a number of the circuits backwards from the Discovery. When spliced together, both the Discovery’s BCU and the Compushift throw error messages.

Others that have done similar installs have suggested connecting the Compushift to the transmission and disconnecting the Rover side, but reprograming the BCU to ‘manual’ from ‘auto’ with a Nanocom. This turns off some of the error lights. However, you also lose the gear position and other automatic transmission-related features, which I like having. This appears to also have an unclear impact on traction control, so I came up with another plan.

The Solution
For the circuits that are backwards, I built an interface box with optocouplers, transistors, and other parts. This basically leaves the Land Rover wiring intact as much as possible, then feeds the signals over to the Compushift in an opposite/inverse fashion. This way both are happy.




The dash works — PRND321 are shown. The mode switch indication is tied to the Compushift. Because the Compushift only has one alternate mode, only the M option is used. The factory transmission computer is removed.

One nice bonus is that this could also be used with other swaps, or even the factory engine, using the Compushift in order to keep the PRND321, etc. working.

Will follow up with more on the install soon.

 

Can you help me with installation of my compushift on my land rover discovery 2?

 

Sure, what do you need help with exactly? Feel free to send me a PM if you would like.

 

Pmed you