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Haltech plug and play harness adaptor question

EFI Wiring Fundamentals

Discussion and questions related to the course EFI Wiring Fundamentals


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I have a MY03 WRX (Australian model) which currently has a Haltech Elite 1500. I originally installed a Platinum Sport 2000 with a plug and play harness adapter which the Elite pretty much plugged straight into with only minor modifications needed to make it work. The only issue was that it was very bulky and never really sat properly in the factory location, and prior to having purchased the wiring courses on here and learning how to properly do wiring there were plenty of really dodgy wiring mods made to the car over the past 16 or so years so I decided to rewire the main ECU and engine harnesses to get rid of the plug and play adapter and wiring the ECU into the car directly. At the same time I replaced most of the connectors and where necessary any damaged wiring also. Plus I also wanted to convert the cable throttle to DBW and install a flex sensor, bigger injectors and a bigger fuel pump ready for E85.

I mean how hard could it be?? Zac makes it all look so easy :)

So anyway, several months later it is all mostly finished and driving again, and the DBW and E85 mods are all working perfectly but there are a few non-haltech related functions that aren't working that must have needed to be plugged into the plug and play adapter (even though the Haltech definitely had nothing to do with these functions).

These are: keyless entry/central locking, rear demister and heater fan (so far anyway but there's probably more).

Given that the factory ECU was replaced with the Haltech which certainly doesn't control the above functions, the connections going from the harness to the other devices could really only be providing either ground or power so there must have been some connections being made inside the plug and play adapter.

Has anyone here had any experience with one of these and if so any information you can provide that would save me having to trawl through wiring diagrams would be greatly appreciated.

That's an interesting one Darren. I don't believe that any of the functions you've mentioned there would have anything to do with the ECU or the adaptor harness at all. Particularly the demister and heater fan really have nothing to do with the engine ECU. I'd be inclined to think the issue is elsewhere and this is a coincidence. I'd personally start by sourcing the wiring diagrams for the car and have a look at the wiring related to the heater/demister unit and trace the operation. It'll be pretty obvious if there's any functionality related to the adapator harness.

Thanks for the reply. I have finally managed to get hold of the exact service manual for the Australian/European delivered 2003 WRX and along with actually having the correct colours listed for the wiring it has also helped answer a whole heap of other questions I've had since I first bought the car brand new that even the dealer wasn't able to answer.

So overall it has been a great source of knowledge even if I still haven't tracked down the exact wires I need to reconnect in order to get the last remaining items working yet. Doesn't help when I keep getting sidetracked running additional wires to the ECU for such things as brake and clutch switches etc but hey isn't that half of the fun when doing these projects?