John2R

Just a 'nudge' on this topic. I guess the question I'm really asking regarding the ECU is "on the AC input / output pins, does +12V mean OFF and 0v mean ON?"

hi, I'm looking for some info on how the Defender TD5 (15P) ECU operates with the air conditioning system. I've been through the wiring diagram and can see that there are : Input (demand request) on pins 4 and 23 (compressor and fan). Output (relays energised) on 9 and 29 From measurement, it appears that all pins float at 12v when 'off'. I can see from the manual that pins 9 and 29 are grounded when the ECU decides that the AC can operate and it energises the relays for compressor clutch and/or fan. However, what is the conditions required for pins 4 and 23 to be grounded? I'm assuming the ECU grounds the input pins, but the manual is not clear on this. Anyone know what the ECU logic is that controls operation of the AC in response to a demand request - which I assume is a 12v 'digital input'. Thanks in advance.

Thanks Paul - very helpful

Thanks - that's it ... and proves the worth of LRCAT over the printed manuals!

hi, I'm trying to find the part number for these cable tie/clip that are used too secure the wiring loom to short screw stud welded to bulkhead and a few other places on a TD5 and I need to replace a few after a rebuild. Can't locate the part number - anyone any idea?