Code 21: Tune Select Resistor
To suit individual market requirements, a tune select resistor is connected across terminals No. 5 & 27 of Engine Control Module (ECM). Tune select resistor is located adjacent to ECM, and strapped to EFI cable assembly. Value of resistor is dependent on market application. For USA models, resistor value is 3900 ohms, with White wire. Code 21 identifies that the tune select resistor is open circuit. To test tune select resistor, see Fig 1 . After completing the tests, retest the vehicle to ensure the faults have been rectified. If faults still persist, recheck using Lucas diagnostic equipment.