Diagnostic Functions MCC
Diagnostic functions MCC
General
The control module has on-board diagnostics (OBD) which monitors input and output signals.
Diagnostic trouble codes (DTCs)
When the control module detects a fault it stores the information in the form of a diagnostic trouble code (DTC) and the orange REC button indicator LED flashes once. Every time the ignition key is turned to position I or II the orange LED will flash once.
If the fault disappears (becomes intermittent) the diagnostic trouble code (DTC) is automatically erased from the control module. In principle the diagnostic trouble codes (DTCs) are erased in the operative cycle after the control module has registered that the diagnostic trouble code (DTC) has disappeared. Depending on what the diagnostic trouble code (DTC) was that was stored this can occur in different ways. If the indicator LED does not flash there are no DTCs stored and no read out is required.
Diagnostic trouble codes (DTCs) 2-3-1, 2-3-2, 2-3-5 and 2-3-6 detect the control signal function directly with ignition on. This means that the diagnostic trouble code (DTC) is erased the next time the ignition is turned on in the operating cycle after the cycle where the fault disappeared or was corrected.
For other diagnostic trouble codes (DTCs) the control module detects the signal/function first when the function is activated, as for example when a motor is activated, or self-adjustment is carried out. This means that diagnostic trouble code (DTC) is erased in the operating cycle after that during which the function was activated and registered as OK, in other words the second operating cycle.
Only when the diagnostic trouble code (DTC) is erased will the orange indicator LED stop flashing when the ignition is switched on.
Diagnostic functions
The Volvo on-board diagnostic (OBD) system functions are activated by pressing the REC button on the unit. The buttons may first be pressed 0.5 seconds after the ignition has been turned on (positions I or II) and then the required combination pressed within following 2.5 seconds .
Note! If a diagnostic trouble code (DTC) is stored, the indicator LED will flash once. Only start pressing the buttons after the flash.
The following functions are available:
- 1 reading off diagnostic trouble codes (DTCs) (initiated by pressing two pushes of the button)
- 2 self-adjustment of the damper motors (initiated by three pushes of the button)
- 3 erasing diagnostic trouble codes (DTCs) (initiated by four pushes of the button).
Refer to the picture for information on how to initiate the sequences and how to interpret the flashes from the indicator LED.
Note! The REC button must be pressed from the out position (off) to the in position (on) in order for it to be counted as a valid entry.
Note!
To ensure the diagnostic functions are activated in the correct way always follow this working method:
- ignition on
- wait approximately 3 seconds
- ignition off
- ignition on again
- wait for 0.5 seconds. If a diagnostic trouble code (DTC) is stored, the indicator LED will flash once. Only start pressing the buttons after the flashing
- activate the required diagnostic function within 2.5 seconds.
To activate diagnostics:
- the ignition must be on
- battery voltage normal.
Reading and erasing diagnostic trouble codes (DTCs)
Stored diagnostic trouble codes (DTCs) can be erased using this function. The on-board diagnostic (OBD) system can identify 10 different faults in the form of diagnostic trouble codes (DTCs).
To reading off diagnostic trouble codes (DTCs), proceed as follows:
- ignition ON, position I or II.
- wait approximately 3 seconds
- ignition off
- ignition on again
- wait for 0.5 seconds. If a diagnostic trouble code (DTC) is stored, the indicator LED will flash once. Only start pressing the buttons after the flashing
- press the REC button in twice within the following 2.5 seconds
- read off the flashes from the REC indicator LED.
The REC indicator LED flashes for 1 second and is off for 0.5 seconds. The timing between the numbers in a DTC code sequence is 2 seconds. The time between two codes is 5 seconds. If no diagnostic trouble codes (DTCs) are set the code will be 1-1-1.
For erasing diagnostic trouble codes (DTCs), proceed as follows:
- ignition ON, position I or II.
- wait approximately 3 seconds
- ignition off
- ignition on again
- wait for 0.5 seconds. If a diagnostic trouble code (DTC) is stored, the indicator LED will flash once. Only start pressing the buttons after the flashing
- press in the REC button four times within the following 2.5 seconds
Note! The diagnostic trouble codes (DTCs) can also be erased by disconnecting the control module for more than 2 minutes (supply voltage power disconnected), because after 2 minutes the entire control module memory will be erased! Diagnostic Trouble Code (DTC) 5 - 1 - 2 can only be erased by disconnecting the control module for more than 2 minutes or by carrying out a successful self-adjustment.
Hint: If the indicator LED still flashes once when the ignition is turned on this means the erasure procedure has not been successfully completed and the diagnostic trouble code (DTC) has again been stored.
The exception is diagnostic trouble code (DTC) MCC 1 - 1 - 1 for certain control modules
Note! Fault-tracing for MCC 3 -4 - 2 should be carried out on the MCC/STANDARD control modules introduced at start of production of the S70/V70/C70. If the REC button orange indicator LED flashes once when the ignition is turned on (diagnostic trouble code (DTC) stored) but the control module flashes out diagnostic trouble code (DTC) 1 - 1 - 1. This applies to control modules marked with "S2", "S3" or " S4". See illustration.
Self-adjustment of damper motors
The climate unit damper motors can be self-adjusted with this service. The damper motors are self-adjusting after any of them has been removed or replaced or other work is carried out on the damper or linkage. To ensure correct self-adjustment the damper motors must have voltage at generator supply level, e.g. the engine must be idling.
To activate self-adjustment, proceed as follows:
- start the engine
- wait approximately 3 seconds
- start engine without switching off the ignition before
- wait 0.5 seconds after the key is released to position II. If a diagnostic trouble code (DTC) is stored, the indicator LED will flash once. Only start pressing the buttons after the flashing
- press the REC button in three times within the following 2.5 seconds.
Note! The control module will automatically self adjust when it is connected to the car's 30-supply on condition that the control module has been disconnected for more than 2 minutes. Engine idling during self-adjustment.