Early/Late EU3 IAT Sensor Wiring Conversion
Caterham K-Series EU3 Wiring Diagram shows wiring to a separate IAT sensor on inlet manifold and no connection to IAT sensor integrated into MAP sensor for all VVC engines. However, it appears that this configuration was used only for early EU3 VVC engines only which continued to use EU2 lower inlet manifold with its separate sensor. The engine in my car is a later EU3 VVC which does not have this sensor on lower manifold and must therefore be wired to make full use of combined MAP/IAT sensor on plenum chamber, however the wiring loom installed matches that shown in wiring diagrams, possessing a plug for sensor which is not installed and no connection for sensor which is installed. As supplied the ECU does not receive IAT information. The loom was therefore modified back to the configuration specified in wiring diagrams for non-VVC engines as described below.
* Engine loom outer tape binding stripped back around junction point of injector sub loom plug spur to allow protective split plastic tubes to be pulled away exposing inner tape binding. Inner tape binding of main body of engine loom and spurs then stripped back to allow access to wiring. Yellow/White wire in engine loom to injector sub loom plug cut at two points: Firstly, in spur to injector sub loom plug, Japanese 3.9mm bullet connector attached to injector sub loom plug cut end. Secondly, within main body of engine loom, remaining wire believed to be NC, loose end folded back, heat shrink insulated and wrapped back into main body of engine loom. Yellow/White wire in engine loom to IAT sensor cut in main body of engine loom, Japanese 3.9mm bullet connector attached to engine loom cut end. Pink/Black wire in engine loom to IAT sensor cut in main body of engine loom, loose end folded back, heat shrink insulated and wrapped back into main body of engine loom. IAT sensor plug removed as both wires now cut. New section of Yellow 0.5mm˛ wire (Yellow/White not available in 0.5mm˛) used to connect two bullet connectors. Inner tape binding of main body of engine loom and spurs repaired, enclosing the insulated cut ends and one bullet connector within the loom. Protective split plastic tubes refitted and engine loom outer tape binding repaired.