V50 T5 AWD L5-2.5L Turbo VIN 67 B5254T7 (2008)
Headlamp Control Module: Testing and Inspection
Initial Inspection and Diagnostic Overview
Headlamp Control Module (HCM)
Diagnostic functions
General
The control module has a built-in diagnostic system, Volvo Diagnostic, which continuously monitors internal functions as well as input and output
signals.
Diagnostic trouble codes (DTCs)
A diagnostic trouble code (DTC) is stored if the control module detects a fault.
A fault which is detected in the most recent operating cycle is defined as permanent. Other faults are defined as intermittent. An operating cycle involves
ignition on, the vehicle speed exceeding 20 km/h and the ignition being switched off.
Reading out and erasing diagnostic trouble codes
Stored diagnostic trouble codes (DTCs) can be read off and erased using this function.
Diagnostic trouble codes (DTCs) can only be erased once all the diagnostic trouble codes (DTCs) have been read off at least once.
Reading off input and output signals
This function can be used to continuously read off the status of the control module's input and output signals. Activating components This function can
be used to activate components to check that they are working.
Reading off the control module identification
The diagnostic tool identifies control modules by reading off a number of codes from the control module memory.
The codes contain the following information about the control module:
-
hardware P/N (control module without software)
-
hardware serial number (control module without software)
-
software P/N
-
diagnostic software P/N (part of the software).
Reading and Clearing Diagnostic Trouble Codes
Description of reading off of extended diagnostic trouble code (DTC) information
Select type of description:
Description of frozen values See: Scan Tool Testing and Procedures/Description Of Frozen Values, HCM
Description of status identifier See: Powertrain Management/Computers and Control Systems/Testing and Inspection/Scan Tool Testing and
Procedures/Description Of Status Identifier
Description of counter See: Powertrain Management/Computers and Control Systems/Testing and Inspection/Scan Tool Testing and
Procedures/Description Of Counter
Component Tests and General Diagnostics
Checking the power supply and ground terminal
Power supply Headlamp Control Module (HCM)
Headlamp Control Module (HCM) is supplied with voltage via a voltage input on the control module.
When the ignition is on, the power input is powered and the control module is in active mode.
-
Voltage input #3 F is supplied with voltage via a fuse from central electronic module (CEM). It will not be possible to activate the control module
if there is an open-circuit.
Checking the power supply
Check the voltage feed cable from the Central electronic module (CEM) #7:1 to the Headlamp Control Module (HCM) #3 F for open-circuit, loose