Suzuki XL7 2007 Service Manual page 1858

7A-44 Heating, Ventilation and Air Conditioning:
Upper or Lower Duct Air Temperature Sensor Malfunction
Diagnostic Fault Information
Perform the "Diagnostic System Check - Vehicle Diagnostic Information: " prior to using this diagnostic procedure.
Circuit
Upper or Lower Duct Air Temperature
Sensor Signal Circuit
Low Reference Circuit
*-circuit inoperative
Circuit/System Description
The upper and lower duct air temperature sensors allow
the HVAC control module to monitor the temperature of
the discharge air in the HVAC instrument panel air ducts.
The module applies 5 volts to internal input resistors that
are connected to the signal circuits of the air
temperature sensors. The module provides ground to
the air temperature sensors through the low reference
circuit. The HVAC control module monitors the voltage
drops across the air temperature sensors and uses the
inputs for automatic control calculations. When the duct
air temperatures are hot, the resistances of the sensors
are low and the voltage signals are low. The HVAC
control module converts the voltage values to count
values where one volt is approximately equal to 51
counts.
Reference Information
Schematic Reference
"HVAC Schematics"
Connector End View Reference
"HVAC Connector End Views"
Description and Operation
• "Air Delivery Description and Operation"
• "Air Temperature Description and Operation"
Electrical Information Reference
• "Circuit Testing: "
• "Connector Repairs: "
• "Testing for Intermittent Conditions and Poor
Connections: "
• "Wiring Repairs: "
Scan Tool Reference
• "Scan Tool Output Controls - HVAC - Automatic"
• "Scan Tool Data List - HVAC - Automatic"
• "Scan Tool Data Definitions - HVAC - Automatic"
Heating Performance Diagnostic
Step
DEFINITION: Heating system performance.
Were you sent here from Symptoms or another diagnostic
1 table?
1. Start the engine.
2
2. Allow the engine to idle.
Does the engine reach a normal operating temperature?
Short to
Ground
*
—
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at
2. Test for less than 1.0 ohm of resistance between the
3. Ignition ON, verify the appropriate upper or lower
4. Install a 3A fused jumper wire between the
5. If all circuits test normal, test or replace the
Repair Instructions
Perform the "Diagnostic Repair Verification - Vehicle
Diagnostic Information: " after completing the diagnostic
procedure.
• "Air Temperature Sensor Replacement - Upper"
• "Air Temperature Sensor Replacement - Lower"
• "Control Module References: " for HVAC Control
Action
Open/High
Short to Voltage
Resistance
*
*
the appropriate upper or lower duct temp sensor.
duct temp sensor ground circuit terminal 2 and
ground.
➢ If greater than the specified range, test the ground
circuit for an open/high resistance.
duct temp sensor parameter is greater than 250
counts (4.9 volts).
➢ If less than the specified value, test the appropriate
upper or lower duct temp sensor signal circuit
terminal 1 for a short to ground. If the circuit tests
normal, replace the HVAC control module.
appropriate upper or lower duct temp sensor signal
circuit terminal 1 and ground. Verify the appropriate
upper or lower duct temp sensor parameter is less
than 5 counts (0.20 volts).
➢ If greater than the specified range, test the
appropriate upper or lower duct temp sensor signal
circuit for a short to voltage or an open/high
resistance. If the circuit tests normal, replace the
HVAC control module.
appropriate upper or lower duct temp sensor.
Module replacement, setup, and programming.
Yes
Go to Step 2
Go to Step 3
Signal
Performance
* —
— —
No
Go to "Symptoms -
HVAC Systems -
Automatic"
Go to Step 9