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Home >> Volvo >> 1997 >> 850 GLT L5-2.4L Turbo VIN 56 B5254T >> Repair and Diagnosis >> Heating and Air Conditioning >> Testing and Inspection >> Initial Inspection and Diagnostic Overview >> Description of On-Board Diagnostics >> Check Solar Sensor

Check Solar Sensor





NOTE: Once test mode 2 is activated, the ECC control module cannot control the atmosphere.

Check that solar sensor is emitting signals as follows:
- Shield the solar sensor (cover it over).
- Start test mode 2. Initializing Test Modes
- Uncover solar sensor and aim a light source (e.g. a flashlight) at the solar sensor from close range. The control module should react to the change in light intensity and respond with an acknowledgement code 1-1-2. The control module will go on flashing the acknowledgement code once test mode 2 is activated.
- If acknowledgement code 1-1-2 does not appear, LED flashes rapidly but no acknowledgement code appears. Cover solar sensor again, use a stronger light source and restart test mode 2. If no acknowledgement code appears, this may mean there is a fault in the solar sensor or in the wires. Go to the next step "Connecting test unit to control module.

Connecting Test Unit To Control Module:





- Ignition off.
- Connect test unit between control module and air-conditioning connector as shown in "Connecting and Disconnecting Test Unit." Connecting and Disconnecting Test Unit
- Check ground, Go to the step "Check GND Points." Connecting and Disconnecting Test Unit
- Go to next step "Check Voltage To Solar Sensor".

Check Voltage To Solar Sensor:





- Ignition on.
- Aim a light source at the solar sensor.
- Connect a DVOM (in mv setting) between # 56 (0 V) and # 51. Read off voltage. Cover solar sensor. Read off voltage again.
If value is OK, voltage (a few mv) should vary with intensity of light. The higher the intensity, the lower the voltage.
If value is not OK, if the voltage is constant or reading is 0 V, there is an open circuit or short to 0 V in the wire or solar sensor.
Go to next step "Check Resistance Of Solar Sensor And Wire".

Check Resistance Of Solar Sensor And Wire:








- Ignition off.
- Disconnect adapter from control module. Connect ohmmeter.

NOTE: The solar sensor is a photoelectric diode, polarity needs to be reversed so readings can be made from two directions.

- Take first resistance reading across # 56 and # 51. If value is OK, ohmmeter reading should be constant and high.
- Take second resistance reading across # 51 and # 56. If value is OK, ohmmeter reading should be a few Mega-ohms.
- If resistance is constant and high both times, there is an open circuit in the wire or solar sensor.
- If resistance is 0 ohm in both readings, there is a ground (GND) fault in the wire or open circuit in the solar sensor.
Go to next step "Check Wire".

Check Wire:











- Ignition off.
- Check wire for short or open circuit as in "Checking Wires". Checking Wires
- Across wire connector pin 2 and connector C pin C:5 to control module.
- Across wire connector pin 4 and connector C pin C:10 to control module.
- If wire is OK, disconnect solar sensor. Replace solar sensor and install in reverse order. Service and Repair Check for proper operation as in"Check Solar Sensor".
- If there is a fault in the wire, correct fault.
Test ECC system as in "Test Procedures". Test Procedures and go to the step - test mode 2 in "Check Solar Sensor"(above).

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