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Electrical System - Fault Tracing: Overview Volvo V50 I

Entertainment Systems 1 illustration ~201 words

DESCRIPTION OF COUNTER

Counter
There are eight different counters that are stored individually for each diagnostic trouble code (DTC). For an intermittent malfunction, the values of the different counters can be studied to determine how intermittent the malfunction is. All counters do not need to be implemented in one control module, this varies from system to system. The possible counters are described below.
CounterFunction
C#1Counts the number of operating cycles since the malfunction was last validated. This information can be used to determine whether the malfunction is active during the current operating cycle or not. The malfunction is present now if the value is zero.
C#2Counts the number of operating cycles since the malfunction was last validated, where test for the diagnostic trouble code was performed without the malfunction being detected and validated. When a test is performed, no malfunction is detected, the counter will count up by 1 for each operating cycle.
C#3Counts the number of operating cycles since the malfunction was validated the first time . For each completed operating cycle the counter will count up by 1.
C#4Counts the number of operating cycles in which the malfunction was validated since it was first validated. Counts the number of times the malfunction has occurred since the first time.
C#5Counts the number of warm-up cycles since the MIL-light has gone off.
C#6The counter counts the number of internal detections of the malfunction that have been performed for the diagnostic trouble code. When this counter reaches + 127, the control module considers that the malfunction is active right now. When counter is at value -127 the malfunction is not active. The value is reset to zero at each new operating cycle. If the value increases toward +127 the control module has detected a malfunction and, for each internal test, the value counts up. When the malfunction is not active, the control module counts down to minimum -127. Value can only be changed when the control module has started the test for the diagnostic trouble code. The increments with which the control module counts up or down the value may vary between control modules.
C#7Shows maximum value for current operating cycle.
C#8Shows maximum value for current and/or earlier operating cycle.

Scheme 391

Scheme 391

DESCRIPTION OF STATUS IDENTIFIER

Status identifier
There are different status identifiers that can be read out for each diagnostic trouble code (DTC). The control module tests each connection more or less continuously. By reading out the diagnostic trouble code (DTC) and the associated status identifier (which detects the malfunction and stores the DTC), information about the test is obtained. Not all status identifiers need to be implemented in one control module, this varies from system to system. All status identifiers are reset and start counting again each time the control module is powered up and when erasing diagnostic trouble codes (DTCs). The possible status identifiers are described below.
Status identifierExplanation
SI#01The malfunction is validated now. Shows if the control module detects the malfunction right now. It is only when the test is in progress that the control module can detect malfunction and generate diagnostic trouble code.
SI#02The malfunction is validated in the current operating cycle. Shows if the control module has detected the malfunction any time during this operating cycle.
SI#03Intermittent not yet confirmed diagnostic trouble code.
SI#04Confirmed diagnostic trouble code.
SI#05Test status in current and/or earlier operating cycle. Shows if control module has performed test for this diagnostic trouble code in current and/or earlier operating cycle.
SI#06The malfunction is validated in an earlier operating cycle. Shows if the control module has detected the malfunction any time during an earlier operating cycle.
SI#07Test status in current operating cycle. Shows if control module has performed test for this diagnostic trouble code in current operating cycle.
SI#08Request activate warning light/text message. Information about the diagnostic trouble code activates a warning light or text message.

GENERAL INFORMATION

The start control unit (SCU) is mounted in the dashboard next to the steering wheel. Besides the cylinder to receive the key, the start control unit (SCU) also contains an antenna cable and four switches. There is one switch for each of the three key positions (I-III) and one to indicate that the key has been inserted into the ignition.

If the keyless vehicle module (KVM) is installed, the key need not be inserted in the ignition where a starter knob is fitted instead. The starter knob must be pressed in before it can be turned from 0 to I and activate the key-in switch. The key identity is checked via the antennae in the passenger compartment that are connected to the keyless vehicle module (KVM).

The ignition's four switches

  1. Key-in switch. Also called S-supply switch.
  2. Ignition X-supply switch.
  3. Ignition 15-supply switch.
  4. Ignition 50-supply switch.

Valid key positions

  1. Key out.
  2. Key position 0.
  3. Key position I.
  4. Key position II.
  5. Key position II/III. Occurs when key turned from position II to III.
  6. Key position III.
Key outKey Pos 0Key Pos IKey Pos IIKey Pos II / IIIKey Pos III
Key inNot activatedActivatedActivatedActivatedActivatedActivated
X-supplyNot activatedNot activatedActivatedActivatedNot activatedNot activated
15 supplyNot activatedNot activatedNot activatedActivatedActivatedActivated
50 supplyNot activatedNot activatedNot activatedNot activatedNot activatedActivated

STATUS OF ALL SWITCHES IN IGNITION FOR VALID KEY POSITIONS