P1552
P1552
Idle Air Control Valve Closing Coil - Below Lower Limit
Function
Idle speed control is realized via the idle air control (IAC) valve. Two coils, the opening coil and closing coil, are integrated in the IAC valve for this purpose.
The basic or emergency position is that adopted when neither of the coils is triggered. To increase the rpm, the opening coil is triggered with a certain pulse duty ratio; to reduce the rpm, the closing coil is triggered.
Diagnosis conditions
A fault is detected and stored in the memory when the engine speed is over 80 rpm and the battery voltage lies between 7.5 and 17 V.
NOTE: If a fault occurs that would lead to very high engine speed, the ignition angle is retarded to limit the rpm.
P1551-P0553:
Wiring Diagram
Diagnosis Procedure
DTC P1551
DTC P1552
DTC P1553
1 Check coil resistance of IAC valve.
1. Remove connector of IAC valve.
2. Connect ohmmeter to pins 2 and 1 of IAC valve.
Display: 14 - 17 ohms at 20 °C.
2 Check wiring from DME control module to IAC valve for continuity.
1. Remove connector of IAC valve.
2. Connect special tool 9616 to wiring harness (DME control module connector).
3. Connect ohmmeter to special tool 9616, pin 2, and to IAC valve connector, pin 1.
Display: 0 - 5 ohms
If Infinity ohm is displayed, check wiring harness for chafing and pinching damage.
3 Check wiring from DME control module to IAC valve for short circuit to ground.
1. Remove connector of IAC valve.
2. Connect special tool 9616 to wiring harness (DME control module connector).
3. Connect ohmmeter to special tool 9616, pin 2, and ground.
Display: Infinity ohm
If 0 - 5 ohms is displayed, check wiring harness for chafing and pinching damage.
4 Check wiring from DME control module to IAC valve for short circuit to B+.
1. Remove connector of IAC valve.
2. Connect special tool 9616 to wiring harness (DME control module connector).
3. Connect voltmeter to special tool 9616, pin 2, and ground.
Display: 0 V
If battery voltage is displayed, check wiring harness for chafing and pinching damage.