Here’s a good test of your Land Rover expertise!

I have a 2004 Discovery II that I swapped to an LS with a 6L80 (I’ll share more when it’s done and done). I have unplugged the tranmission control unit, yet the “limp mode” lights are still illuminated (Manual, Sport, and blinking D in the PRNDL). According to all electrical diagrams that I can find (including the one for 03MY), this shouldn’t be possible as the Manual/Sport lights are illuminated by the TCU.

I have the RW Engineering CANbus gateway, which communicates between the GM ECM and Land Rover systems. The traction control and HDC are also illuminated (no ABS) but I suspect these are linked to the “limp mode” issue.

Does anyone know how these lights can be illuminated? Is there a “limp mode” signal that is being sent to the BCU or IDM?

 

I have the answer, I think, but I want to talk to you about other things and I'm not sure if you're still around.

 

FYI, this was solved by setting the Rover's BCM to manual transmission mode. This works because the manual transmissions do not have a transmission computer so the Rover stops looking for one and the lights turn off. You'll need a Land Rover programming tools or a local shop with one.