Climate Units - Design and Function (Convertible): Diagnosis Volvo C70 I

Diagnostic trouble codes (DTCs)

If the control module detects a fault it stores a diagnostic trouble code (DTC) and the orange indicator LEDs in the REC and air conditioning (A/C) buttons flashes for approximately 20 seconds. The control module can store up to 38 diagnostic trouble codes (DTCs). If the total diagnostic trouble code (DTC)s exceeds 10 the five first diagnostic trouble code (DTC)s will always be saved, while the last five become the latest diagnostic trouble code (DTC)s to be stored.

If for some reason a fault disappears after the diagnostic trouble code (DTC) has been permanently stored in the control module, information about the fault is stored in the control module.

Every diagnostic trouble code (DTC) has a counter which records the number of cycles which have been " fault-free" since the diagnostic trouble code (DTC) was stored (intermittent fault). A cycle is defined from when the ignition was switched on, was then on for at least 10 seconds and then switched off. Every time the cycle runs without the control module registering the fault again, increases the counter by 1. Using the counter it is possible to determine if the control module interprets diagnostic trouble code (DTC) as permanent or intermittent. When the counter is at 0 the transmission control module (TCM) treats the malfunction as a permanent fault. If the counter value is greater than 0 the control module interprets this as meaning the fault is intermittent.

Scheme 394

Fault data and other information can be read off using the VIDA PC which is connected to the data link connector (DLC) under the center console cover.

Volvo on-board diagnostic (OBD) system

With the VIDA PC it is possible to

1. read and erase diagnostic trouble codes (DTCs), counters and frozen values
2. Continuously monitor the value and status of input and output signals
3. self-adjust the damper motors
4. program the control module with certain information
5. read off control module identification.

To activate the Volvo on-board diagnostic (OBD) system

1. ignition on
2. battery voltage normal.

Note. For self-adjustment of the damper motors the engine must be running at idle (generator (GEN) charging).

Reading and erasing diagnostic trouble codes (DTCs)

Stored diagnostic trouble codes (DTCs) and counters can read out and erased using this service. The on-board diagnostic (OBD) system can identify 38 different faults in the form of diagnostic trouble codes (DTCs).

Diagnostic trouble codes (DTCs) can only be erased when all stored diagnostic trouble codes (DTCs) have been read off at least once.

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.

Scheme 395

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

1. the ignition must be on
2. battery voltage normal.

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

1. ignition ON, position I or II.
2. wait approximately 3 seconds
3. ignition off
4. ignition on again
5. 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
6. press the REC button in twice within the following 2.5 seconds
7. 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

1. ignition ON, position I or II.
2. wait approximately 3 seconds
3. ignition off
4. ignition on again
5. 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
6. 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

Scheme 396

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".

If the control module detects a fault it will store a diagnostic trouble code (DTC). The control module can store up to 23 diagnostic trouble codes (DTCs).

If for some reason a fault disappears after the diagnostic trouble code (DTC) has been permanently stored in the control module, information about the fault is stored in the control module.

Reading off Volvo on-board diagnostic (OBD) system

Fault data and other information can be read off using the VIDA PC which is connected to the data link connector (DLC) under the center console cover.

With the VIDA PC it is possible to

1. read off and erase diagnostic trouble codes (DTCs) stored.
2. read off and erase the low current protection status.
3. continuously monitor the value and status of input and output signals.
4. activate certain functions.
5. program the control module with certain information.
6. read the control module identification.

To activate the Volvo on-board diagnostic (OBD) system

1. ignition on.
2. battery voltage normal.

Stored diagnostic trouble codes (DTCs) can be erased using this function. The on-board diagnostic (OBD) system can identify 23 different faults in the form of diagnostic trouble codes (DTCs).

Erasing diagnostic trouble codes (DTCs) can only be carried out when all diagnostic trouble codes (DTCs) have been read at least once.

A diagnostic trouble code (DTC) is stored if the timer detects a fault. The timer can store up to 4 diagnostic trouble codes (DTCs).

Fault data and other information can be read off using the VIDA PC which is connected to the data link connector (DLC).

With the VIDA PC it is possible to

1. read off and erase diagnostic trouble codes (DTCs) stored.

To activate the Volvo on-board diagnostic (OBD) system

1. ignition on.
2. battery voltage normal.

Stored diagnostic trouble codes (DTCs) can be erased using this function. The on-board diagnostic (OBD) system can identify 4 different faults in the form of diagnostic trouble codes (DTCs).

Erasing diagnostic trouble codes (DTCs) can only be carried out when all diagnostic trouble codes (DTCs) have been read at least once.