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Home >> Volvo >> 1996 >> 850 Turbo L5-2.3L Turbo VIN 57 B5234FT >> Repair and Diagnosis >> A L L Diagnostic Trouble Codes ( DTC ) >> Testing and Inspection >> Manufacturer Code Charts >> EFI / DTC Codes (Engine Control System) >> DTC 4-4-4

DTC 4-4-4

4-4-4 ACCELERATION SENSOR, SIGNAL

Preconditions for DTC
^ If the ECM senses that the direct-current signal from the Acceleration Sensor has changed its mean setting (2.5 Volts) to more than 3.5 Volts or less than 1.5 Volts, DTC 4-4-4 is set.

Substitute value
^ None.

Fault sources
^ Signal too high:
- Signal lead short circuited to voltage supply.
- Break in signal, ground or voltage lead.
- Voltage lead short circuited to ground.
- Contact resistance in connectors.
- Defective acceleration sensor.

^ Signal too low:
- Signal lead short circuited to ground.
- Defective acceleration sensor.

Fault symptoms
^ May result in misfiring DTCs when driving on bumpy roads.

TESTING PROCEDURE





Status Message
^ Check current status message.

If Status message is: Permanent fault, signal too high:
- Proceed to: PERMANENT FAULT, SIGNAL TOO HIGH section below.
If Status message is: Permanent fault, signal too low:
- Proceed to: PERMANENT FAULT, SIGNAL TOO LOW section below.
If Status message is: Intermittent fault, signal too high:
- Proceed to: INTERMITTENT FAULT, SIGNAL TOO HIGH section below.
If Status message is: Intermittent fault, signal too low:
- Proceed to: INTERMITTENT FAULT, SIGNAL TOO LOW section below.

PERMANENT FAULT, SIGNAL TOO HIGH





Checking the Voltage Lead
^ Switch Ignition OFF.
^ Wait for approx. 150 seconds.
^ Disconnect the acceleration sensor.
^ Connect an ohmmeter between the acceleration sensor connector 1 and ground.

The ohmmeter should show 5 - 20K ohms.

If reading is OK:
- Check the ground lead.
If the ohmmeter shows infinite resistance:
- Check the ECM's connector.
If the ohmmeter shows approx. 0 ohms:
- Check the wiring to the A/C pressure sensor.





Checking the ECM Connector
^ Switch Ignition OFF.
^ Acceleration sensor disconnected.
^ Rectify the ECM's connector with regard to contact resistance and oxidation.
^ ECM connected.





^ Connect an ohmmeter between the acceleration sensor connector 1 and ground.

The ohmmeter should show 5 - 20K ohms.

If reading is OK:
- The source of the DTC is poor contact in the ECM's connector.
If the reading is incorrect:
- Check the lead between acceleration sensor connector 1 and ECM B1 for signs of a break.





Checking the Wiring to the A/C Pressure Sensor
^ Switch Ignition OFF.
^ Acceleration sensor disconnected.
^ Disconnect the A/C pressure sensor.
^ Connect an ohmmeter between acceleration sensor connector 1 and ground.

If the ohmmeter shows approx. 0 ohms:
- Check the voltage lead to the A/C pressure sensor.
If the ohmmeter shows 5 - 20K ohms:
- Test with a new A/C pressure sensor.





Checking the Voltage Lead to the A/C Pressure Sensor
^ Switch Ignition OFF.
^ Acceleration sensor disconnected.
^ Connect the A/C pressure sensor.
^ Disconnect the ECM.
^ Connect an ohmmeter between acceleration sensor connector 1 and ground.

If the ohmmeter still shows approx. 0 ohms:
- Check the lead between acceleration sensor connector 1 and ECM B1 for signs of short circuiting to ground.
If the reading changes to infinite resistance:
- Check the lead between A/C pressure sensor connector 3 and ECM B29 for signs of short circuiting to ground.





Checking the Ground Lead
^ Switch Ignition OFF.
^ Acceleration sensor disconnected.
^ Connect an ohmmeter between acceleration sensor connector 2 and ground.

The ohmmeter should show approx. 0 ohms.

If reading is OK:
- Check the signal lead.
If the reading is incorrect:
- Check the ECM's connector.





Checking the ECM Connector
^ Switch Ignition OFF.
^ Acceleration sensor disconnected.
^ Rectify the ECM's connector with regard to contact resistance and oxidation.
^ ECM connected.





^ Connect an ohmmeter between acceleration sensor connector 2 and ground.

The ohmmeter should show approx. 0 ohms.

If reading is OK:
- Check the signal lead.
If the reading is incorrect:
- Check the lead between acceleration sensor connector 2 and ECM B28 for signs of a break.





Checking the Signal Lead
^ Switch Ignition ON.
^ Acceleration sensor disconnected.
^ Connect a voltmeter between acceleration sensor connector 3 and ground.

The voltmeter should show approx. 5 Volts.

If reading is OK:
- Check the acceleration sensor.
If the voltmeter shows more than 5 Volts:
- Check the lead between acceleration sensor connector 3 and ECM B32 for signs of short circuiting to voltage supply.
If the voltmeter shows approx. 0 Volts:
- Check the ECM connector.





Checking the ECM Connector
^ Switch Ignition OFF.
^ Acceleration sensor disconnected.
^ Rectify the ECM connector with regard to contact resistance and oxidation.
^ ECM connected.
^ Switch Ignition ON.





^ Connect a voltmeter between acceleration sensor connector 3 and ground.

The voltmeter should show approx. 5 Volts.

If reading is OK:
- The source of the DTC is poor contact in the ECM connector.
If the reading is incorrect:
- Check the lead between acceleration sensor connector 3 and ECM B32 for signs of a break.





Checking the acceleration sensor
^ Switch Ignition ON.
^ Connect the acceleration sensor.
^ Delete the DTC.





^ START the engine and let it run at idling speed.

If the DTC does not recur:
- The source of the DTC is poor contact in the acceleration sensor connector.
- Rectify the connector with regard to contact resistance and oxidation.
If the DTC recurs:
- Test with a new acceleration sensor.

PERMANENT FAULT, SIGNAL TOO LOW





Checking the Signal Lead
^ Switch Ignition OFF.
^ Disconnect the acceleration sensor.
^ Switch Ignition ON.
^ Connect a voltmeter between acceleration sensor connector 3 and ground.

The voltmeter should show approx. 5 Volts.

If reading is OK:
- Test with a new acceleration sensor.
It reading is incorrect:
- Check the lead between acceleration sensor connector 3 and ECM B32 for signs of short circuiting to ground.

INTERMITTENT FAULT, SIGNAL TOO HIGH





Checking the Leads and Connections
^ Check the acceleration sensor and ECM connectors for signs of loose connection and contact resistance and oxidation.
^ Check the lead between acceleration sensor connector 1 and ECM B1 for signs of an intermittent break.
^ Check the lead between acceleration sensor connector 1 and ECM B1 for signs of intermittent short circuiting to ground.
^ Check the lead between acceleration sensor connector 2 and ECM B28 for signs of an intermittent break.
^ Check the lead between acceleration sensor connector 3 and ECM B32 for signs of intermittent short circuiting to voltage supply and intermittent break.
^ Check the lead between A/C pressure sensor connector 3 and ECM B29 for signs of intermittent short circuiting to ground.

INTERMITTENT FAULT, SIGNAL TOO LOW





Checking the Leads and Connections
^ Check the lead between acceleration sensor connector 3 and ECM B32 for signs of intermittent short circuiting to ground.










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