diagnostic functions.

Design and Function

Applies to: 2007–2012; B5254T10, B5254T11, B5254T6, B5254T8

Overview

See: Overview

Misfire diagnostic

See: Misfire diagnostic

Camshaft diagnostics (CVVT)

See: Camshaft diagnostics (CVVT)

Leak diagnostics (certain markets only)

See: Leak diagnostics, original version (certain markets only)

Heated oxygen sensor (HO2S) diagnostic

See: Heated oxygen sensor (HO2S) diagnostic

Three-way catalytic converter (TWC) diagnostics

See: Three-way catalytic converter (TWC) diagnostics

Fuel pressure regulation, diagnostics

See: Fuel pressure regulation, diagnostics

Ethanol-related fuel control (only applies to version flexifuel)

See: Control, Flexifuel (B5254T8)

Oil level and oil temperature sensor, diagnostics (certain markets only)

See: Oil level and oil temperature sensor, diagnostics (certain markets only)

Applies to: 2009–2016; D5204T2, D5204T3, D5204T7, D5244T10, D5244T11, D5244T14, D5244T15, D5244T19

General

The engine control module (ECM) diagnoses both internal signals and functions as well as signals and functions from connected components.

Conditions for diagnosis

For the diagnosis of a component or function to start, certain specific conditions must be met. The conditions for diagnostics vary depending on the component or function being diagnosed.

Conditions must be met during the diagnostic in order for the diagnostic to be completed. The time and conditions for the diagnostic vary depending on the component or function being diagnosed. Certain diagnostics only require the ignition to be switched on and off for a diagnostic to be run. Other diagnostics require that several different conditions are met. For example:

• vehicle speed
• engine coolant temperature (ECT)
• time since start
• different load and engine speed relationships in the same trip
• a certain event (for example the EGR valve is operating).

When the engine control module (ECM) has run all the implemented diagnostics, the control module has completed a "trip". An extensive driving schedule in various conditions is required to complete a trip. The engine may also need to be shut off for a certain amount of time and then switched on again to complete a trip.

Emissions related diagnostic functions

The engine control module (ECM) checks that the emissions related systems are working. These systems are checked by running a diagnostic function. The diagnostic function checks the components and that the system is functioning.

Diagnostic trouble code (DTC) memory

When the engine control module (ECM) detects a fault, the diagnostic trouble code and status are stored in the diagnostic trouble code memory and are visible during normal diagnostic trouble code readout. If the diagnostic trouble code (DTC) lights the malfunction indicator lamp (MIL), this occurs at the same time. If an existing fault disappears and does not recur, the engine control module changes the status of the diagnostic trouble code after a certain number of fault-free operating cycles (depending on the nature of the diagnostic trouble code). This means that it can no longer be read during normal diagnostic trouble code readout. In this status, the diagnostic trouble code remains until the engine control module (ECM) erases diagnostic trouble codes or is disconnected from power.

Substitute value

For certain types of diagnostic trouble codes (DTCs), the missing signal is replaced with a substitute value so that the system can continue functioning.

Fuel pressure regulation, diagnostics

General

The fuel pump control module has no functions for diagnostics. Fuel pressure control components and functions are diagnosed by the engine control module (ECM).

The following components and functions are diagnosed by the engine control module (ECM). Diagnostic trouble codes (DTCs) can be stored for each component and function:

• Fuel pump control module, a diagnostic checks the power supply. A diagnostic trouble code (DTC) will be stored and the fuel pump will not work if there is no power supply to the fuel pump control module
• Fuel pressure, the engine control module (ECM) compares the requested pressure with the measured pressure(signal from the fuel pressure sensor). If the measured pressure deviates excessively from the requested pressure, or if the pressure pulses, a diagnostic trouble code (DTC) will be stored for incorrect fuel pressure. The diagnostic is not active if a diagnostic trouble code (DTC) for the fuel pressure sensor is stored. A diagnostic trouble code (DTC) for fuel pressure will be stored if there is a fault in the fuel pump.
• Communication cable. The engine cannot be started if there is a fault in the communication cable between the engine control module (ECM) and the fuel pump control module. A diagnostic trouble code (DTC) will be stored for the fault.

For further information about diagnostic trouble codes (DTCs), see Diagnostic trouble code (DTC) information for the diagnostic trouble codes (DTCs).

Components and functions which cannot be diagnosed:

If there is a fault in the by-pass valve in the tank unit, the starting process of the engine will take longer if the valve is leaking fuel when the fuel pump is off. If the valve does not open when there are pressure peaks in the fuel system, engine operation will be affected negatively, especially after engine braking. The fault can also cause rough idling.

Applies to: 2009–2016; MPS6

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)

If the control module detects a fault then it stores a diagnostic trouble code (DTC). If a fault disappears for any reason after a diagnostic trouble code (DTC) has been permanently stored in the control module then the information on the diagnostic trouble code (DTC) remains in the control module.

Reading and erasing diagnostic trouble codes (DTCs)

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

The status for some of the control module's input and output signals can be continuously read off using this function.

For more information about parameters, see Vehicle communication information in Specifications, other.

Reading off the control module identification

The control module can be identified by means of reading off a number of codes.

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.