Ignition System
ON-BOARD DIAGNOSTICS EZ-129K IGNITION SYSTEM
Each of the control modules incorporates Volvo Diagnostics, which continuously monitor the input and output signals. In the event of a fault which affects the exhaust emission levels, the Ignition Control Module (ICM) will activate the MIL (Check engine lamp) on the combined instrument. Fault tracing may be carried out either with the Scan Tool or by means of the three test modes, which can be accessed through socket "6" on DLC "A".
Diagnostic test modes (DTM):
^ Mode 1 Displays Diagnostic Trouble Codes (DTCs) (if any are stored)
^ Mode 2 Acknowledges component operation
^ Mode 3 Operates components in a given, predetermined sequence
TROUBLE CODE DISPLAY - IGNITION SYSTEM (DI)
The DI system diagnostics can be accessed through socket number 6 on DLC A when the ignition is switched ON.
Diagnostic Test Mode 1
DTM 1 is activated by a single brief operation of the Data Link Connector (DLC) test button. The ICM responds by displaying any stored DTC's.
Erasing DTCs
The DTCs may be erased only when all stored DTCs have been displayed at least once and the first DTC has been repeated.
Press and hold the test button for at least 5 seconds. The LED will light 3 seconds after the button has been released. Press the button again for at least 5 seconds.
Diagnostic Test Mode 2
DTM 2 is activated by two brief operations of the test button on the DLC, causing the LED to flash rapidly. The ICM will deliver an acknowledgement code on detecting a change in the signals from:
^ Engine Speed Sensor, acknowledgement code (1-4-1) given as flywheel/carrier plate rotates.
^ Camshaft Position Sensor, acknowledgement code (3-4-2) given as camshaft rotates.
^ Speedometer, acknowledgement code (3-4-3) given as front wheels rotate.
^ Multi-port Fuel Injection Module, acknowledgement code (3-4-4) given when Throttle Position Potentiometer is activated by way of throttle operation.
Diagnostic Test Mode 3
DTM mode 3 is activated by three brief operations of the test button on the DLC. The ICM responds by operating the following components, in the order listed:
^ Variable Intake System Solenoid Valve, for 5 seconds
^ 5-second pause
^ Engine Cooling Fan, at half speed, for 3 seconds, followed by full speed operation for 3 seconds (fan runs at half speed for 6 seconds in cars without A/C)
^ 5-second pause
^ EGR Controller, for 5 seconds (certain models only; 5- second pause in cars without EGR)
^ 5-second pause
^ Tachometer in combined instrument, for 5 seconds, by generating engine speed signals equivalent to approx. 1500 rpm
The sequence is repeated three times.