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Isuzu D-Max / Isuzu Rodeo (TFR/TFS). Manual - part 1875
7A2-116 DIAGNOSIS
No. D1: Faulty Gear Shifting (Different from Shift Pattern)
Description:
•
Gear is shifted, different from the specified shift pattern.
Diagnosis Hints:
•
When inspecting faulty gear shifting, it is important to distinguish between the fault of electric system and
mechanical system (AT main unit).
•
Fault of electric system.
Monitor the output signal (each solenoid driving signal) using with Tech 2. If a trouble signal is sent to the
solenoid synchronously with the faulty gear shifting, the fault is originated in the electric system.
Monitor the input signal (signal from each sensor) using with Tech 2 and find an input signal by which the output
signal (each solenoid driving signal) is subjected to fault.
Fault of the electric system may be derived from temperature or vibration. For instance, though the engine is
normal while it is cold, fault may occur when the engine is warmed up or vehicle is running.
•
Fault of mechanical system.
If the gear is incorrectly shifted irrespective of operating signal (ON-OFF) of each solenoid, the faulty is
originated from the machine system (AT).
If the clutch slips, ATF smells burnt, contaminated to be black or the stall speed increases.
Possible Cause:
•
Disordered select cable.
•
Disordered inhibitor switch.
•
Slip
of
clutch.
If slip of clutch is caused, a DTC (gear ratio error) is stored.
•
Fixing at 3rd position (fail-safe activated)
Since the gear is fixed at the 3rd position because of the fail-safe function, a trouble that "Faulty gear
shifting" is resulted. In this case, the DTC is memorized.
When TCM stops operation because of faulty TCM ground, the gear is fixed at the 3rd position because
of a mechanical reason. In this case, no DTC is memorized.
••••
Incorrect properties of throttle opening signal (serial communication) of throttle position sensor.
The throttle opening signal which is sent by serial communication from ECM and TCM is an important
signal for gear shifting. In case of ECM fault or when the throttle position sensor does not issue voltage
signal according to the throttle opening, the gear is not shifted by stepping over the accelerator.
If the output voltage of the throttle position sensor changes freely even though the throttle opening is
constant, the gear is shifted incorrectly.
•
Faulty speed sensor.