Just thought I would follow up on the question I originally asked and some of the responses. There actually wasn’t a break or bad connection as suggested. The Calais earthed via the brown/white wire back through the BCM so it can measure the voltage drop and then give you wonderful warnings on the dash about tail lights or stop light globes being blown. The Lumina earthed via the black/blue wire which went straight to the body of the vehicle. So all that was required was backing out the brown/white wire from X4-24 and turning that into an body earth wire which I attached to the body via the 10mm dash mounting bolt near the BCM. Problem solved.
The cruise control works fine too as it operates off its own switch at the brake pedal. I don’t think it uses the same earth as the tail lights, brake lights and number plate lights. That earth wire was the only thing I changed to match the original car the engine and trans came out of.
Not trying to step on any toes, just wanted to provide some follow up info so others aren’t put off trying this kind of thing. You don’t need to change the loom or anything full on like that. It was simply the engine and ECU, trans and TCM, BCM, PIM and key fob from the donor car. The only modification was that X4-24 wire which needed to be changed to a body earth and not a BCM earth. The Lumina had no wire fitted to the connector in that position.
The only thing I haven’t corrected as yet, is the ESP failure warning. Due to the fact it doesn’t run the original 5 speed with ESP or a 4 speed with ESP. My original donor car also didn’t have traction control. So after start up I get the ESP failure warning, I hit the mode button and this changes to ESP off and Trac off on the dash. It has no effect on the drivability of the car and I don’t even notice it. I would however like to look at changing the ABS module over from the donor car to see if this corrects the issue. Only difference between the two units is one has three lines out of it (donor car) and the other four lines out (Calais). But to be honest it might not be worth the hassle as there isn’t any real effect on the car besides the warning.
