Dtc15 - Ckp Sensor System Fault; Conditions For Clearing Mil/Dtc - Isuzu 4HL1 Workshop Manual

DTC15 - CKP Sensor System Fault

Circuit Description
The CKP (crank position) sensor is installed to the
flywheel housing and, when flywheel teeth pass the
sensor, a CKP signal is generated. Ninety CKP pulses
are generated per cycle (one rotation of crankshaft).
The ECM identifies the cylinder from the CKP signal as
well as the CMP signal sent from the CMP sensor and
determines the crank angle, and uses this angle in fuel
injection control and engine speed calculation. These
tasks are usually performed utilizing the CKP signal but
if the CKP sensor fails, the CMP signal will substitute
for the CKP signal.
DTC15 will be set when the number of CKP signals
received by the ECM is not correct.
Major Faulty Event
• Poor startability
• Poor driveability
Conditions for Setting the DTC
No CKP signal is input while the CMP signal is input to
the ECM 40 times.
Action Taken When the DTC Sets
• After the DTC is set and the engine runs at idle,
the ECM will illuminate the CHECK ENGINE lamp
(MIL).
• When the CMP sensor is sound, the ECM will
control the powertrain using the CMP signal.
6 8 27 26
25
CKP CMP
Sensor Sensor
63 66 6764
69 68
ITP EGR Valve
Sensor Position
Sensor

Conditions for Clearing MIL/DTC

When the system fails and the DTC is stored to the
ECM, even repairing the faulty portion will not clear the
DTC from the memory. To clear the DTC, conduct the
following steps.
1. Turn off the idle position switch for not less than 1
second but not more than 3 seconds. (Press the
accelerator pedal.)
2. Turn on the idle position switch for not less than 1
second but not more than 3 seconds. (Release the
accelerator pedal.)
3. Turn off the idle position switch for not less than 1
second but not more than 3 seconds. (Press the
accelerator pedal.)
4. Turn on the idle position switch for not less than 1
second but not more than 3 seconds. (Release the
accelerator pedal.)
5. Turn off the idle position switch for not less than 1
second but not more than 3 seconds. (Press the
accelerator pedal.)
6. After the above operations are properly completed,
the CHECK ENGINE lamp (MIL) illuminates for 3
seconds to report the memory is cleared.
7. Turn off the starter switch. Wait for 5 seconds and
turn on the starter switch again.
When Tech 2 has been connected to the vehicle, the
DTC can be cleared through the memory clear
operation with Tech 2.
Engine Control System 1A-97
ECM
(Engine
Control
Module)
Common
Rail
Pressure
Sensor
LNW21AMF006901-X