Fail-Safe/Backup Function (Limp-In Mode)

Diagnostic item Control during malfunction

No cam signal at PCM The PCM uses the crankshaft position sensor signal only to control fuel injection timing, etc. (Accordingly, normal sequential multiport fuel injection may not be carried out.)

Throttle position sensor voltage low The PCM uses the value calculated from the MAP sensor signal instead of the throttle valve opening angle (voltage).

Throttle position sensor voltage high The PCM uses the value calculated from the MAP sensor signal instead of the throttle valve opening angle (voltage).

Engine coolant temperature (ECT) sensor - The PCM uses the default value [4500 (1140 F)] as the engine coolant temperature.
voltage too low - The PCM operates the radiator fan.
- The PCM carries out open loop control.

Engine coolant temperature - The PCM uses the default value [4500 (114°F)] as the engine coolant temperature.
(ECT) sensor voltage too
- The PCM operates the radiator fan.
high
- The PCM carries out open loop control.

Upstream HO2S stays at center The PCM carries out open loop control.

No vehicle speed sensor signal The PCM controls the engine as if the vehicle speed were 0 mph.

MAP sensor voltage too low The PCM uses the value calculated from the throttle position sensor and the engine speed signals instead of the MAP value (mV).

MAP sensor voltage too high The PCM uses the value calculated from the throttle position sensor and the engine speed signals instead of the MAP value (mV).

No change in MAP from start to run The PCM uses the value calculated from the throttle position sensor and the engine speed signals instead of the MAP value (m\L)

Intake air temperature sensor
voltage low The PCM uses the engine coolant temperature instead of the intake air temperature.



Intake air temperature sensor voltage high The PCM uses the engine coolant temperature instead of the intake air temperature.

Knock sensor The PCM retards ignition timing according to the knock sensor signal.

Upstream HO2S shorted to voltage The PCM carries out open loop control.

Battery temperature sensor volts out of limit The PCM uses the default value [6200 (1440 F)] as the battery temperature.

Low speed fan control relay circuit The PCM turns on the high speed fan control relay instead of the low speed fan control relay

Upstream HO2S response The PCM carries out open loop control.

Downstream HO2S shorted to voltage The PCM carries out open loop control.

Downstream HO2S stays at center The PCM carries out open loop control.


TPS voltage does not agree with MAP The PCM uses the value calculated from the MAP sensor signal instead of the throttle valve opening angle (voltage).

Timing belt skipped 1 tooth or more The PCM uses the crankshaft position sensor signal only to control fuel injection timing, etc. (Accordingly, normal sequential multiport fuel injection may not be carried out.)

No 5 volts to MAP sensor The PCM uses the value calculated from the throttle position sensor and the engine speed signals instead of the MAP value (mV).

No 5 volts to throttle position sensor The PCM uses the value calculated from the MAP sensor signal instead of the throttle valve opening angle (voltage).

High speed radiator fan control relay circuit The PCM turns on the high speed fan control relay instead of the low speed fan control relay

Upstream HO2S voltage
shorted to grounded The PCM carries out open loop control.

Downstream HO2S voltage
shorted to grounded The PCM carries out open loop control.

Intermittent loss of CMP or CKP The PCM uses the crankshaft position sensor signal only to control fuel injection timing, etc. (According, normal sequential multiport fuel injection may not be carried out.)