OAP Pete
As EX Auto Elect [ Now retired, i can only tell you the Circuit to the ISCV... When engine running you should [ with the ISCV plug off Solonoid] have battery voltage to one terminal, the other terminal goes to ECU.. the ECU needs to see Water sensor for injection system [ rear of Head] to adjust idle...ie Cold to Hot.. Check the circuit. Sorry i cant help any more. If the Water sensor was "Duff" then you would be getting for sure more faults....ie High Fuel consumption... rough running... Check the Water sensor plug...and wiring back to ECU, Pete.