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Home >> Volvo >> 1996 >> 850 Turbo L5-2.3L Turbo VIN 57 B5234FT >> Repair and Diagnosis >> Heating and Air Conditioning >> Testing and Inspection >> Initial Inspection and Diagnostic Overview >> Description of On-Board Diagnostics >> Connecting and Disconnecting Test Unit

Connecting and Disconnecting Test Unit

CAUTION: When connecting and disconnecting the test unit, the control module must be switched off, otherwise there is a risk of damaging the control module or causing a lot of diagnostic trouble codes (DTCs) to be stored.

NOTE: When using the test unit to take readings on the air conditioning (A/C) system control module, it must be connected to adapter 9813194-9.

Using The Test Unit:





- Test unit 9813190 is designed to help readings made:
- Of control module input and output signals, when the control module is connected during the readings.
- Of wire and component resistances, when the control module is disconnected during readings.
- The test unit also helps make readings more accurate by making it easier to see and get to the test points. It also reduces the risk of accidentally shorting cables or damaging connector pins.
When using the test unit in the fault-tracing procedures described in ALLDATA, it is important to know the basic checks to be made and the designations used. These are described in the "Test procedures"and the "Fault-tracing procedure". Test Procedures and Fault Tracing Procedures

Disconnecting Control Module:








- Ignition off.
- Remove radio.
- Insert hand underneath control module:
- Push up locking button on underside of control module. Push control module loose from behind (from one rear corner).
- Remove control module.
- Disconnect three connectors from control module.
- Go to next step "Connecting test unit to control module.

Connecting Test Unit To Control Module:





- Ignition off.
- Connect adapter between control module and air-conditioning system connectors. This connection is used when taking readings on electronic circuits with the control module connected. Go to the step "Check GND points".

Connecting Test Unit Without Control Module:





- Ignition off.
- Disconnect adapter from control module and put control module aside. The test unit is now connected to the A/C system connectors. This is used to take resistance readings direct on wires and components in the ECC system with the control module disconnected.

Check GND Points:





- Ignition off
- Connect an ohmmeter between GND (chassis) and:
# 6 to check power ground.
# 9 to check signal ground.
# 10 to check control of signal ground.
# 56 to check signal ground.
Ohmmeter reading should be on in each case.
- If all values OK, this means the voltage is 0 V at these points (provided battery - terminal is connected to chassis). Return to fault-tracing where you left off to connect test unit.
- If any value is not OK, if ohmmeter shows a constant high reading, this means there is a GND fault in the circuit. Go to the step "Check wires" for the GND point which varied from 0 ohm.

Check Wiring:








- If the ohmmeter reading showed a constant high value for # 9, # 10 or # 56, this means either that there is an internal fault in the control module or a faulty wire in the test unit and adapter. Go to the step "Check test unit".
- If ohmmeter reading showed a constant high value for # 6 in the step "Check GND Points" above, this means there is an open circuit in the wire to GND point 31/10 or a faulty wire in the test unit and adapter. Check wire between connector A pin A:6 to control module and GND point 31/10 for breaks as in "Checking Wires". Checking Wires
- If there is an open circuit in the wire:
- Rectify fault.
- Check DTCs as step in "Fault Tracing Procedures". Fault Tracing Procedures
- If wire OK, go to the step "Check Test Unit".

Check Power Supply To Control Module:





- Ignition on.
- Connect a voltmeter between # 10 (0 V) and # 1. Voltmeter should show battery voltage.
- If value is OK, return to fault-tracing procedure where you left off and connect test unit.
- If voltmeter reads 0 V, GND fault or open circuit in wire.
Check fuse 31.
Check wire for GND fault or open circuit as in "Checking Wires". Between connector A pin A:1 to control module and branching point 23/305. Between branching point 23/305 and fuse 31. Checking Wires
- Rectify fault.
- Check DTCs as in step "Fault Tracing Procedures". Fault Tracing Procedures

Check Power Supply To Damper Motor Position Sensor:








- Ignition on.
- Connect voltmeter between # 10 (0 V) and # 8. Voltmeter reading should be 5 V.
- If value is OK, return to fault-tracing procedure where you left off and connect test unit.
- If voltmeter reads 0 V, GND fault or open circuit in wire or damper motor position sensor.
- Check wire for GND fault as in "Checking Wires". Between connector A pin A:8 to control module and branching point 23/307. Between branching point 23/307 and wire contacts connection pin 2 to the different damper motor position sensors. Checking Wires
- Check damper motor position sensors across pins 1 and 2.
- Rectify GND fault in wire or replace damper motor.
- Check DTC as in step "Fault Tracing Procedures". Fault Tracing Procedures
- If voltmeter reads 12 V, short to 12 V in wire. Check wire for short to 12 V as in "Checking Wires". Between connector A pin A:8 to control module and branching point 23/307. Between branching point 23/307 and wire contacts connection pin 2 to the different damper motor position sensors. Checking Wires
- Rectify short.
- Check DTCs as in step "Fault Tracing Procedures". Fault Tracing Procedures

Check Test Unit:





- Ignition off.
- Disconnect test unit from control module and air-conditioning system connector.
- Check wiring inside test unit for any GND points which are not 0 ohm as in step "Check GND Points".
- Connect an ohmmeter across:
- Test unit # 6 and adapter connector A pin A:6.
- Test unit # 9 and adapter connector A pin A:9.
- Test unit # 10 and adapter connector A pin A:1O.
- Test unit # 56 and adapter connector C pin C:10.
- Ohmmeter should read 0 ohm.
- If not, disconnect adapter 9813194-9 from test unit and check wires inside test unit and adapter to see where open circuit is. Replace test unit or adapter as necessary. Go back to step "Check GND Points".
- If value is OK, there is a fault in the control module. Replace control module and re-test and carry out self-adjustment of damper motor limit positions. Self Adjustment of Damper Motor Limit Positions

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