Suzuki XL7 2007 Service Manual page 1856

7A-42 Heating, Ventilation and Air Conditioning:
Auxiliary Blower Motor Malfunction
Diagnostic Instructions
• Perform the "Diagnostic System Check - Vehicle Diagnostic Information: " prior to using this diagnostic procedure.
• "Strategy Based Diagnosis: "
• "Diagnostic Procedure Instructions - Vehicle Diagnostic Information: "
Diagnostic Fault Information
Circuit
Rear Blower Motor Speed Control
Aux. Blower Motor Control Module Ground
Blower Speed Feed Back Signal
Auxiliary Blower Motor Low Reference
Auxiliary Blower Motor Ground
Auxiliary Blower Motor B+
1. Always ON
2. Inoperative
Circuit/System Description
Auxiliary HVAC Control Module
The front HVAC control module must be in the ON
position for GMLAN communication to allow the rear
HVAC control module to operate.
Auxiliary Blower Motor Control Module
The following are auxiliary blower motor control module
circuits:
• Rear blower motor speed control circuit - When the
auxiliary blower switch is placed in any speed position
this circuit is a pulse width modulated signal that is
sent from the Auxiliary HVAC control module to the
auxiliary blower motor control module.
• Ground - A constant body ground is supplied to the
auxiliary blower motor control module.
• Low reference - This circuit is grounded through the
auxiliary blower motor control module only when the
auxiliary HVAC control module is in high speed. In all
other blower speeds this circuit is a pulse width
modulated signal (PWM). The longer this circuit is
pulsed the ground the faster the blower speed will be.
• Blower speed feed back signal - This feedback circuit
displays in percent on the TECH 2 the commanded
output blower speed that the auxiliary blower motor
control module is sending to the auxiliary blower
motor.
Auxiliary Blower Motor
The following are auxiliary blower motor circuits:
• Ground - A constant body ground is supplied the
blower motor.
• Ignition voltage - Ignition voltage is supplied to the
blower motor from the underhood fuse box.
• Low reference - This circuit is grounded through the
auxiliary blower motor control module only when the
auxiliary HVAC control module is in high speed. In all
other blower speeds this circuit is a pulse width
modulated signal (PWM). The longer this circuit is
pulsed the ground the faster the blower speed will be.
Short to Open/High
Ground Resistance
2 2
— 2
2 2
1 2
— 2
2 2
Reference Information
Schematic Reference
"HVAC Schematics"
Connector End View Reference
"HVAC Connector End Views"
Description and Operation
"Air Delivery Description and Operation"
Electrical Information Reference
• "Circuit Testing: "
• "Connector Repairs: "
• "Testing for Intermittent Conditions and Poor
Connections: "
• "Wiring Repairs: "
Scan Tool Reference
• "Scan Tool Data List - HVAC - Automatic"
• "Scan Tool Output Controls - HVAC - Automatic"
• "Scan Tool Data Definitions - HVAC - Automatic"
Signal
Short to Voltage
Performance
2
—
2
2
2
—
—
—
—
—
—
—