Fuel Injection System

ON-BOARD DIAGNOSTICS LH3.2 MULTI-PORT INJECTION 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 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 "2" on DLC "A", located in engine compartment.

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 - FUEL INJECTION SYSTEM (MFI)
The MFI system diagnostics can be accessed through socket number 2 on DLC A when the ignition is switched ON.

Checking For More Codes:

Diagnostic Test Mode 1
DTM 1 is activated by a single brief operation of the Data Link Connector (DLC) test button. The MFI module 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.

Entering Control Function #2:

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 MFI module will deliver an acknowledgement code on detecting a change in the signals from:

^ Throttle Position Potentiometer, acknowledgement code (3-3-2) given when throttle is moved from Closed Throttle Position.

^ Throttle Position Potentiometer, acknowledgement code (3-3-3) given when throttle is moved from Wide Open Throttle.

^ Ignition Control Module, acknowledgement code (1-1-4) given when A/C switch is closed.

^ Pressostat, acknowledgement code (1-3-4) given when A/C compressor starts.

^ AW 50-42 Transmission Control Module, acknowledgement code (1-2-4) given when gear selector lever is moved to or from a drive position.

^ Ignition Control Module, acknowledgement code (3-3-1) given when speed signals are transmitted.

Entering Control Function #3:

Diagnostic Test Mode 3
DTM 3 is activated by three brief operations of the test button on the DLC. The MFI module responds by operating all the following components, in the order listed:

^ Fuel Injectors, for 5 seconds.

^ 5-second pause.

^ Idle Air Control Valve, for 5 seconds.

The sequence is repeated three times.