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Possible Causes

PINPOINT TEST 6: DEFROST SYSTEM IS INOPERATIVE

PINPOINT TEST 6 THE DEFROST SYSTEM IS INOPERATIVE
STEP INSPECTION ACTION
1 CHECK THE SJB DTCs
  • Retrieve the recorded DTC results from the SJB for the continuous and on-demand self-test.
  • Is DTC B1345 present? 
 Yes GO to step 9.
No Go to next step.
2 CHECK THE REAR WINDOW DEFROST RELAY
  • Key OFF.
  • Disconnect the Rear Window Defrost Relay.
  • Carry out the component test on the rear window defrost relay. See the POWER WINDOWS for schematic information.
  • Did the rear window defrost relay pass the component test? 
 Yes Go to next step.
No INSTALL a new rear window defrost relay. TEST the system for normal operation.
3 CHECK THE REAR WINDOW DEFROST RELAY FEED CIRCUITS FOR VOLTAGE
  • Measure the voltage between the rear window defrost relay pin 1, circuit (B), harness side and ground; and between the rear window defrost relay pin 3, circuit (B), harness side and ground.
  • Are the voltages greater than 10 volts? 
 Yes GO to step 5.
No Go to next step.
4 CHECK CIRCUIT (B) FOR AN OPEN
  • Disconnect the SJB J-2280b.
  • Measure the voltage between the SJB J-2280b pin 1, circuit (B), harness side and ground.
  • Is the voltage greater than 10 volts? 
 Yes GO to step 13.
No REPAIR the circuit. TEST the system for normal operation.
5 CHECK CIRCUIT (BR/LB) FOR VOLTAGE
  • Connect the Rear Window Defrost Relay.
  • Disconnect the Rear Window Defrost Grid 0912-102.
  • Key ON, Engine OFF (KOEO).
  • Press the rear window defrost switch to the ON position.
  • Measure the voltage between the rear window defrost grid 0912-102 pin 1, circuit (BR/LB), harness side and ground.
  • Is the voltage greater than 10 volts? 
 Yes Go to next step.
No GO to step 7.
6 CHECK THE GRID GROUND FOR AN OPEN
  • Key OFF.
  • Disconnect the Rear Window Defrost 0912-103.
  • Measure the resistance between the rear window defrost 0912-103 pin 1, circuit (B), harness side and ground.
  • Is the resistance less than 5 ohms? 
 Yes INSTALL a new liftgate window glass.
See LIFTGATE WINDOW GLASS . TEST the system for normal operation.
No REPAIR the circuit. TEST the system for normal operation.
7 CHECK CIRCUIT (BR/LB) FOR AN OPEN
  • Key OFF.
  • Disconnect the SJB J-2280c.
  • Measure the resistance between the SJB J-2280c pin 1, circuit (BR/LB), harness side and the rear window defrost grid 0912-102 pin 1, circuit (BR/LB), harness side.
  • Is the resistance less than 5 ohms? 
 Yes Go to next step.
No REPAIR the circuit. TEST the system for normal operation.
8 CHECK CIRCUIT (DL/O) FOR AN OPEN
  • Disconnect the SJB J-2280e.
  • Disconnect the Rear Window Defrost Switch 0912-101.
  • Measure the resistance between the SJB J-2280e pin 14, circuit (DL/O), harness side and the rear window defrost switch 0912-101 pin 2, circuit (DL/O), harness side.
  • Is the resistance less than 5 ohms? 
 Yes Go to next step.
No REPAIR the circuit. TEST the system for normal operation.
9 CHECK CIRCUIT (DL/O) FOR A SHORT TO GROUND
NOTE:
  • A short to ground on circuit (DL/O) sets DTC B1345. The SJB then ignores input from the rear window defrost switch and causes the rear window defrost to be inoperative.
  • Key OFF.
  • Disconnect the Rear Window Defrost Switch 0912-101.
    NOTE:
    • Make sure the rear window defrost relay is disconnected.
  • Measure the resistance between rear window defrost switch 0912-101 pin 2, circuit (DL/O), harness side and ground.
  • Is the resistance greater than 10,000 ohms? 
 Yes GO to step 11.
No Go to next step.
10 CHECK THE SJB FOR AN INTERNAL SHORT
  • Disconnect the SJB J-2280e.
  • Measure the resistance between rear window defrost switch 0912-101 pin 2, circuit (DL/O), harness side and ground.
  • Is the resistance greater than 10,000 ohms? 
 Yes GO to step 13.
No REPAIR the circuit. TEST the system for normal operation.
11 CHECK CIRCUIT (B/W) FOR AN OPEN
  • Measure the resistance between the rear window defrost switch 0912-101 pin 1, circuit (B/W), harness side and ground.
  • Is the resistance less than 5 ohms? 
 Yes Go to next step.
No REPAIR the circuit. TEST the system for normal operation.
12 CHECK THE REAR WINDOW DEFROST SWITCH
  • Measure the resistance between the rear window defrost switch 0912-101 pin 1 and pin 2, component side, while pressing and releasing the switch.
  • Is the resistance less than 5 ohms with the switch pressed and greater than 10,000 ohms with the switch released? 
 Yes Go to next step.
No INSTALL a new rear window defrost switch. TEST the system for normal operation.
13 CHECK FOR CORRECT SJB OPERATION
  • Disconnect all the SJB connectors.
  • Check for:
    • corrosion
    • pushed-out pins
  • Connect all the SJB connectors and make sure they seat correctly.
  • Operate the system and verify the concern is still present.
  • Is the concern still present? 
 Yes INSTALL a new SJB. See SMART JUNCTION BOX (SJB) for the removal and installation procedure. TEST the system for normal operation.
No The system is operating correctly at this time. Concern may have been caused by a loose or corroded connector. TEST the system for normal operation.
G03727124Courtesy of MAZDA MOTORS CORP.
G03727125Courtesy of MAZDA MOTORS CORP.
G03727126Courtesy of MAZDA MOTORS CORP.
G03727127Courtesy of MAZDA MOTORS CORP.
G03727128Courtesy of MAZDA MOTORS CORP.
G03727129Courtesy of MAZDA MOTORS CORP.
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