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Home >> Volvo >> 1996 >> 850 L5-2.4L VIN 55 B5254S >> Repair and Diagnosis >> Powertrain Management >> Computers and Control Systems >> Testing and Inspection >> Component Tests and General Diagnostics >> Communication Problems With Scan Tool >> With Automatic Transmission >> With California Emissions (Emissions Code G1)

With California Emissions (Emissions Code G1)

COMMUNICATIONS PROBLEM WITH VOLVO SCAN TOOL





Possible Source(s)
If the engine starts:
- Poor battery voltage.
- Open-circuit, short-circuit to ground or short-circuit to supply voltage in cable to data link connector (DLC).
- Open-circuit in data link connector power supply, power ground or signal ground.
- Defective Volvo Scan Tool (ST), Volvo Scan Tool wiring or adapter box.

If engine will not start:
- Short-circuit to ground in 15-supply between fuse and control module
- Open-circuit in 15-supply
- Open-circuit in 30-supply
- Open-circuit in supply from main relay
- Open-circuit in control signal, main relay.

NOTE: If communications problems only occurs when starting the engine: connect a battery charger or extra battery.





Starting The Engine
- Does the engine start?

Yes:
^ Proceed to test step below.

No:
^ Proceed to Checking Engine Immobilizer section below.





Checking Power Supply
- Ignition on.
- Volvo Scan Tool (ST) connected to data link connector (DLC).
- Power up the Scan Tool and check that the display lights up.
- Does the display light?

Yes:
^ Proceed to Checking Communication With ABS System section below.

No:
^ Proceed to test step below.





Checking Data Link Connector Power Supply
- Ignition off.
- Disconnect the Volvo Scan Tool.
- Disconnect the data link connector.
- Connect a voltmeter between data link connector terminal 16 and ground.
- The voltmeter should read battery voltage.

If reading is OK:
^ Proceed to Checking Data Link Connector Power Ground section below.

If reading is incorrect:
^ Proceed to test step below.





Checking Fuse 15
- Check that fuse 15 is intact.
- Is the fuse intact?

Yes:
^ Proceed to test step below.

No:
^ Check cable between data link connector terminal 16 and fuse 15 for a short-circuit to ground.





Checking Voltage Before The Fuse
- Ignition off.
- Connect a voltmeter between the rear socket of the fuse holder to fuse 15 and ground.
- The voltmeter should read battery voltage.

If reading is OK:
^ Check cable between fuse 15 and data link connector terminal 16 for an open-circuit.

If reading is incorrect:
^ Check the cable between fuse 15 and battery positive terminal for an open-circuit.





Checking Data Link Connector Power Ground
- Ignition off.
- Connect ohmmeter between data link connector terminal 4 and ground.
- The ohmmeter should read approx. 0 ohms.

If reading is OK:
^ Proceed to test step below.

If reading is incorrect:
^ Check cable between data link connector terminal 4 and ground terminal (31/15) by the passenger side A-pillar for an open-circuit.





Checking Data Link Connector Signal Ground
- Ignition off.
- Connect ohmmeter between data link connector terminal 5 and ground.
- The ohmmeter should read approx. 0 ohms.

If reading is OK:
^ Proceed to test step below.

If reading is incorrect:
^ Check cable between data link connector terminal 4 and ground terminal (31/15) by the passenger side A-pillar for an open-circuit.





Checking Supply Voltage To Adapter Box
- Ignition on.
- Volvo Scan Tool connected to data link connector.
- Separate Scan Tool wiring at the adapter box.
- Connect a voltmeter between the 25-pin connector terminal:
^ 15 (data link connector side) and ground.
^ 20 (data link connector side) and ground.
^ 21 (data link connector side) and ground.
^ 22 (data link connector side) and ground.

- The voltmeter should read battery voltage for all readings.

If reading is OK:
^ Proceed to test step below.

If reading is incorrect:
^ Try new Scan Tool wiring.





Checking Power Ground To Adapter Box
- Ignition off.
- Connect Scan Tool wiring to data link connector.
- Disconnect Scan Tool wiring from adapter box.
- Connect ohmmeter between 25-pin connector terminal:
^ 23 (data link connector side) and ground.
^ 24 (data link connector side) and ground.
^ 25 (data link connector side) and ground.

- The ohmmeter should read 0 ohms for all readings.

If reading is OK:
^ Proceed to test step below.

If reading is incorrect:
^ Try new Scan Tool wiring.





Checking Adapter Box Signal Ground
- Ignition off.
- Connect Scan Tool wiring to data link connector.
- Disconnect Scan Tool wiring from adapter box.
- Connect an ohmmeter between the 25-pin connector terminal 14 (data link connector side) and ground.
- The ohmmeter should read 0 ohms.

If reading is OK:
^ Proceed to test step below.

If reading is incorrect:
^ Try new Scan Tool wiring.





Checking Supply To Scan Tool
- Ignition on.
- Connect Scan Tool wiring to data link connector.
- Connect Scan Tool to adapter box.
- Disconnect the 3-pin connector from the Scan Tool.
- Power switch on adapter box should be on.
- Connect a voltmeter between the 3-pin connector terminal:
^ 1 (data link connector side) and ground.
^ 3 (data link connector side) and ground.

- The voltmeter should read:
^ Between terminal 1 and ground: 7 - 9 Volts.
^ Between terminal 3 and ground: Battery Voltage.

If reading is OK:
^ Proceed to test step below.

If reading is incorrect:
^ Try a new adapter box.





Checking Scan Tool Ground
- Ignition off.
- Connect Scan Tool wiring to data link connector.
- Disconnect the 3-pin connector from the Scan Tool.
- Connect an ohmmeter between the 3-pin connector terminal 2 (data link connector side) and ground.
- The ohmmeter should read 0 ohms.

If reading is OK:
^ Try a new Scan Tool.

If reading is incorrect:
^ Try a new adapter box.





Checking Communication With ABS System
- Ignition on.
- Volvo Scan Tool connected to data link connector.
- Try to establish communication with the ABS system.
- Has communication with the ABS system been established?

Yes:
^ Check cable between data link connector terminal 7 and engine control module (ECM) # B36 for an open-circuit.

No:
^ Proceed to test step below.





Checking Communication Cable To The Data Link Connector
- Disconnect the Scan Tool from the data link connector.
- Connect the test box and check ground terminals.
- Disconnect the immobilizer (if equipped) and bridge it to the car with jumper P/N 9162590.
- Ignition off.
- Connect an ohmmeter between data link connector terminal 7 and test box terminal # 36 (B36).
- The ohmmeter should read 0 ohms.

If reading is OK:
^ Proceed to test step below.

If reading is incorrect:
^ Check cable between data link connector terminal 7 and engine control module # B36 for an open-circuit.





Checking The Communication Cable
- Connect the engine control module.
- Ignition on.
- Connect a voltmeter between data link connector terminal 7 and ground.
- The voltmeter should read approx. 9 - 11 Volts.

If reading is OK:
^ Proceed to test step below.

If value is lower:
^ Check cable between data link connector terminal 7 and control modules connected to this cable for short-circuit to ground.

If value is higher:
^ Check the cable between data link connector terminal 7 and the control modules connected to this cable for a short-circuit to ground.





Checking Communication Cable To Adapter Box
- Ignition on.
- Connect Scan Tool wiring to data link connector.
- Separate Scan Tool wiring at the adapter box.
- Connect an ohmmeter between the 25-pin connector terminal 5 (data link connector side) and ground.
- The voltmeter should read 9 - 11 Volts.

If reading is OK:
^ Proceed to test step below.

If reading is incorrect:
^ Try new Scan Tool wiring.





Checking Communication With The Scan Tool
- Ignition on.
- Connect Scan Tool wiring to data link connector.
- Connect Scan Tool wiring to data link connector.
- Disconnect the 62-pin connector from the Scan Tool.
- Check that the switch on the adapter box is on.
- Connect a voltmeter between the 62-pin connector terminal 47 (Scan Tool side) and ground.
- Try to establish communication with the engine control module.
- Voltage should be approx 8.6 Volts, it should then start to oscillate rapidly between 8.6 Volts and 0 Volts as the Scan Tool tries to establish contact.

If reading is OK:
^ Try a new adapter box.

If reading is incorrect:
^ Try a new Scan Tool.





Checking Engine Immobilizer (if equipped)
- If there is a fault in the immobilizer the Motronic 4.4 engine control module may not be allowed to start. It is important to check that the immobilizer is free of faults before continuing this fault-tracing.
- Check appearance of ignition key to determine whether the car has an immobilizer (refer to image).
- Key 1: The car has an immobilizer.
- Key 2: The car does not have an immobilizer.
- Does the car have an immobilizer?

Yes:
^ Proceed to test step below.

No:
^ Proceed to Checking Fuse 1 section below.





Checking Diagnostic Trouble Codes In The Immobilizer
- Ignition on.
- Check for diagnostic trouble codes stored in the immobilizer.
- If the immobilizer has been checked and remedied but the engine still does not start: Select Alternative 1.
- If communication cannot be established with the immobilizer: Select Alternative 2.
- If there are diagnostic trouble codes stored in the immobilizer: Select Alternative 3.
- If there are no diagnostic trouble codes stored in the immobilizer: Select Alternative 4.
- Select a suitable alternative.

Alternative 1:
^ Proceed to Checking Fuse 1 section below.

Alternative 2:
^ Fault-trace the Immobilizer Antitheft System.

Alternative 3:
^ Fault-trace the Immobilizer Antitheft System.

Alternative 4:
^ Proceed to Checking Fuse 1 section below.





Checking Fuse 1
- Check that fuse 1 is intact.
- Is the fuse intact?

Yes:
^ Proceed to test step below.

No:
^ Check the circuit for a short-circuit to ground.





Checking 15-supply Before The Fuse
- Ignition on.
- Connect a voltmeter between the right socket on the fuse 1 fuse holder and ground.
- The voltmeter should read battery voltage.

If reading is OK:
^ Proceed to Checking The 15-supply After The Fuse section below.

If reading is incorrect:
^ Proceed to test step below.





Checking The 15-supply From The Ignition Switch
- Ignition off.
- Disconnect the connector from the ignition switch.
- Switch ignition to position II.
- First connect an ohmmeter between ignition switch terminals 15 and 30 and then between ignition switch terminal 15 and the other ignition switch terminal 30
- In both cases the ohmmeter should read 0 ohms.

If reading is OK:
^ Proceed to test step below.

If reading is incorrect:
^ Try a new ignition switch.





Checking Power Supply To Ignition Switch
- Ignition off.
- Disconnect ignition switch connector.
- First connect a voltmeter between ignition switch connector terminal 30 and ground and then between the other ignition switch terminal 30 and ground.
- In both cases the voltmeter should read battery voltage.

If reading is OK:
^ Check cable between ignition switch connector terminal 15 and fuse 1 for an open-circuit.

If reading is incorrect:
^ Check the cable between battery positive terminal and ignition switch terminal 30 for an open-circuit.





Checking The 15-supply After The Fuse
- Connect the test box and check ground terminals.
- Reinstall the fuse.
- Connect engine control module.
- Ignition on.
- Connect a voltmeter between # 42 (# A42) and # 12 (# A12).
- The voltmeter should read battery voltage.

If reading is OK:
^ Proceed to test step below.

If reading is incorrect:
^ Check cable between left fuse holder socket and engine control module # A12 for an open-circuit.





Checking The 30-supply
- Ignition on.
- Connect a voltmeter between # 42 (# A42) and # 26 (# A26).
- The voltmeter should read battery voltage.

If reading is OK:
^ Proceed to test step below.

If reading is incorrect:
^ Check cable between engine control module # A26 and battery for an open-circuit.





Checking Power Supply From Main Relay
- Ignition on.
- Connect a voltmeter between # 27 (# A27) and # 42 (# A42) on the test box.
- The voltmeter should read battery voltage.

If reading is OK:
^ Check all signals to and from engine control module.

If reading is incorrect:
^ Proceed to test step below.





Checking Voltage To Main Relay Terminal 4
- Ignition off.
- Disconnect connector from main relay (2/32).
- Connect a voltmeter between main relay connector terminal 4 and ground.
- The voltmeter should read battery voltage.

If reading is OK:
^ Proceed to test step below.

If reading is incorrect:
^ Check the cable between main relay terminal 4 and battery positive terminal for an open-circuit.





Checking Voltage To Main Relay Terminal 2
- Ignition off.
- Remove main relay.
- Connect a voltmeter between main relay connector terminal 2 and ground.
- The voltmeter should read battery voltage.

If reading is OK:
^ Proceed to test step below.

If reading is incorrect:
^ Check the cable between main relay terminal 2 and battery positive terminal for an open-circuit.





Checking Control Signal To Main Relay
- Ignition on.
- Remove main relay.
- Connect a voltmeter between main relay connector terminal 1 and the battery positive terminal.
- The voltmeter should read battery voltage.

If reading is OK:
^ Proceed to test step below.

If reading is incorrect:
^ Check cable between engine control module # A41 and main relay terminal 1 for an open-circuit.





Checking Voltage From Main Relay
- Ignition on.
- Connect main relay to connector.
- Does the relay click when it is connected to the connector?

Yes:
^ Check cable between the engine control module # A27 and main relay terminal 3 for an open-circuit.

No:
^ Proceed to test step below.





Checking Signal Cable
- Ignition off.
- Disconnect main relay from connector.
- Connect an ohmmeter between main relay connector terminal 3 and ground.

If reading is 0 Ohms:
^ Check cable between engine control module # A27 and main relay terminal 3 for a short-circuit to ground.

NOTE: This cable also goes to:
- All injectors terminal 1.
- Heated oxygen sensor heating terminal 1.
- Idle air control valve terminal 2.
- EVAP canister shut-off valve terminal 1.
- Pulsed secondary air injection system solenoid valve terminal 1.
- Mass air flow sensor terminal 3.
- Canister purge valve terminal 1.
- Replace main relay when the fault has been remedied.

If reading is more than 0 Ohms:
^ Try a new main relay.
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