Trouble Code E.7.2
The ECM supplies 12 volt signal to pin B of ISC motor. When engine is at idle speeds, throttle linkage contacts ISC plunger and closes throttle switch which pulls voltage on pin B of ISC motor down to 0 volts.
NOTE:
The following step numbers refer to the numbers in the accompanying flow chart(s).
- Code indicates that throttle switch is malfunctioning. With ignition on and code displayed, push actuator plunger into its stop. If this results in code passing, check for mechanical binding in throttle linkage, such as throttle blades, shafts, throttle cable, cruise control linkage, TV cable, TPS, or throttle return springs. Also check minimum air rate adjustment which may be holding throttle open. Binding linkage is preventing throttle switch from closing.
- If code remains, check ISC plunger and idle switch for binding in fully retracted position. If ISC plunger is binding, disconnect ISC motor and extend plunger by momentarily jumpering 12 volts to pin D of ISC motor and jumpering pin C to ground. Reconnect ISC motor and repeat switch tests.NOTE: Only pins C and D of ISC motor have voltage applied to them. Jumpering ISC pins A and C will damage ISC motor.
- With ignition on and code displayed, disconnect ISC motor and momentarily jumper harness pins A and B together. If code disappears, then replace ISC motor.
- If code remains, then problem is in wiring harness or ECM. To identify defective component, measure voltage on harness pin B with ignition on. If voltage is 12 volts, then check circuit No. 450 for open. If circuit No. 450 has continuity, then check for faulty ECM connector or faulty ECM. If voltage is less than 1 volt, then check circuit No. 427 for open or short to ground. If circuit No. 427 is okay, check for faulty ECM connector or faulty ECM because it is not providing required 12 volt signal.