B1840
B1840 - Sunroof Open Switch Input Circuit/Performance
For a complete wiring diagram, refer to.
Theory of Operation
The sunroof motor/module supplies a 12 volt supply circuit to the sunroof switch. When the switch is closed to any of the 3 sense circuits (open, close or vent), it sends that command back to the module.
• When Monitored: Whenever the sunroof module is awake.
• Set Condition: Whenever the module has determined that the open switch has been applied for over 15 seconds, there is a short to voltage, a short to ground or an open on the sunroof open switch sense circuit.
Test Step 1 - Test for an Intermittent Condition
• Turn the ignition ON.
• With the scan tool, record and erase DTCs.
• Press and release the sunroof switch in all positions several times.
• Wait 30 seconds.
• With the scan tool, check for DTCs.
Does the scan tool display B1840 - Sunroof Open Switch Input Circuit/Performance?
Yes
• Go to Test Step 2
No
• The conditions that caused this code to set are not present at this time. Check the switch for any binding conditions, and repair any obvious problems. If no obvious problems were found, use the wiring diagram/schematic as a guide and inspect the wiring and connectors for an intermittent condition.
Test Step 2 - Check the Sunroof Switch
• With the scan tool, erase DTCs.
• Turn the ignition OFF.
• Disconnect the sunroof switch harness connector.
• Turn the ignition ON and wait 30 seconds.
• With the scan tool, check for DTCs.
Does the scan tool display this DTC as active?
Yes
• Go to Test Step 3
No
• Replace the sunroof switch.
• Perform the Body Verification Test. Refer to => Non-DTC Based Diagnostics. Body Interior
Test Step 3 - Check the Sunroof Open Switch Sense Circuit for a Short to Voltage
• To further diagnose the sunroof, it is necessary to lower or remove the headliner.
• Turn the ignition OFF.
• Lower the headliner to gain access to the sunroof motor/module harness connector.
• Disconnect the sunroof motor/module harness connector.
• Ensure the A - Pillar connector is connected before proceeding.
• Turn the ignition ON.
• Measure the voltage between the sunroof open switch sense circuit and ground in the sunroof motor/module harness connector.
Is the voltage more than 0.4 volts?
Yes
• Repair the sunroof open switch sense circuit for a short to voltage.
• Perform the Body Verification Test. Refer to => Non-DTC Based Diagnostics. Body Interior
No
• Go to Test Step 6
Test Step 4 - Check the Sunroof Open Switch Sense Circuit for a Short to Ground
• Turn the ignition OFF.
• Ensure the A - Pillar connector is connected before proceeding.
• Measure the resistance between ground and the sunroof open switch sense circuit in the sunroof motor/module harness connector.
Is the resistance less than 10k ohms?
Yes
• Repair the sunroof open switch sense circuit for a short to ground.
• Perform the Body Verification Test. Refer to => Non-DTC Based Diagnostics. Body Interior
No
• Go to Test Step 5
Test Step 5 - Check the Sunroof Open Switch Sense Circuit for an Open
• Turn the ignition OFF.
• Ensure the A - Pillar connector is connected before proceeding.
• Measure the resistance of the sunroof open switch sense circuit between the sunroof switch harness connector and the sunroof motor/module harness connector.
Is the resistance less than 5.0 ohms?
Yes
• Repair the sunroof open switch sense circuit for a short to ground.
• Perform the Body Verification Test. Refer to => Non-DTC Based Diagnostics. Body Interior
No
• Go to Test Step 6
Test Step 6 - Check the Sunroof Open Switch Sense Circuit for a Short to the Sunroof Switch Supply Circuit
• Turn the ignition OFF.
• Disconnect the A - Pillar connector.
• Measure the resistance between the sunroof open switch sense circuit and the sunroof switch supply circuit in the sunroof motor/module harness connector.
Is the resistance less than 10k ohms?
Yes
• Repair the sunroof open switch sense circuit for a short to the sunroof switch supply circuit.
• Perform the Body Verification Test. Refer to => Non-DTC Based Diagnostics. Body Interior
No
• Replace the sunroof motor/module.
• Perform the sunroof position calibration. Perform the excessive force limitation calibration.
• Perform the Body Verification Test. Refer to => Non-DTC Based Diagnostics. Body Interior