Pinpoint Test H: LFC 18/DTC B1890
Air Bag and Safety Belt Pretensioner Supplemental Restraint System (SRS)
Pinpoint Tests
Pinpoint Test H: LFC 18/DTC B1890
Refer to Wiring Diagram Set 46, Supplemental Restraint System for schematic and connector information. Diagrams By Number
Normal Operation
The Restraints Control Module (RCM) has the ability to deactivate the passenger air bag under certain conditions. When the passenger air bag is deactivated, the Passenger Air Bag Deactivation (PAD) switch warning indicator will be illuminated.
The RCM monitors the PAD warning indicator for short to battery conditions. If the RCM detects a short to battery condition on the PAD warning indicator circuit, it will store a DTC B1890 in memory and send a message to the Instrument Cluster (IC) module to flash Lamp Fault Code (LFC) 18 (or higher priority code if one exists) on the air bag warning indicator.
- DTC B1890 (PAD Warning Lamp Circuit Short to Battery) - If the RCM detects a short to battery on the PAD indicator circuit when the indicator is activated for greater than 2.2 seconds, it will set this DTC.
This pinpoint test is intended to diagnose the following:
- Wiring, terminal or connectors
- PAD switch
- RCM
PINPOINT TEST H: LFC 18/DTC B1890
NOTICE: Use the correct probe adapter(s) from the Flex Probe Kit when taking measurements. Failure to use the correct probe adapter(s) may damage the connector.
Most faults are due to connector and/or wiring concerns. Carry out a thorough inspection and verification before proceeding with the pinpoint test. Inspection and Verification
NOTE: Supplemental Restraint System (SRS) components should only be disconnected or reconnected when instructed to do so within a pinpoint test step. Failure to follow this instruction may result in incorrect diagnosis of the SRS.
NOTE: The SRS must be fully operational and free of faults before releasing the vehicle to the customer.
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H1 RETRIEVE RCM DTCs
- Enter the following diagnostic mode on the scan tool: Self Test - RCM.
- Was DTC B1890 retrieved on-demand during self-test?
Yes
This fault cannot be cleared until it is corrected and the DTC is no longer retrieved on-demand during self-test. GO to H2.
No
This is an intermittent fault when present as a Continuous Memory Diagnostic Trouble Code (CMDTC) only. GO to H4.
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H2 CHECK THE PAD SWITCH WARNING INDICATOR
- Place the PAD switch in the OFF position.
- Does PAD warning indicator illuminate?
Yes
INSTALL a new RCM. REFER to Restraints Control Module (RCM) Service and Repair. GO to H5.
No
GO to H3.
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H3 CHECK PAD SWITCH CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Depower the SRS. Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.
- Disconnect: RCM C310A and C310B.
- Disconnect: PAD Switch C2099.
- Repower the SRS. Do not prove out the SRS at this time. Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.
- Ignition ON.
- Measure the voltage between PAD switch C2099-2, circuit RR116 (BN/GN), harness side and ground.
- Is any voltage present?
Yes
REPAIR circuit RR116 (BN/GN). GO to H5.
No
INSTALL a new PAD switch. REFER to Passenger Air Bag Deactivation (PAD) Switch Service and Repair. GO to H5.
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H4 CHECK FOR AN INTERMITTENT FAULT
- Enter the following diagnostic mode on the scan tool: Self Test - RCM.
- Was DTC B1890 retrieved on-demand during self-test?
Yes
This fault cannot be cleared until it is corrected and the DTC is no longer retrieved on-demand during self-test. GO to H2.
No
CHECK for causes of the intermittent short to voltage on circuit RR116 (BN/GN). ATTEMPT to recreate the hard fault by flexing the wire harness and cycling the ignition key frequently. Do not install any new SRS components at this time. SRS components should only be installed when directed to do so in the pinpoint test. REPAIR any intermittent wiring, terminal or connector concerns found. GO to H5.
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H5 CHECK FOR ADDITIONAL SRS DTCs
- Ignition OFF.
- WARNING: Turn the ignition OFF and wait one minute to deplete the backup power supply. Failure to follow this instruction may result in serious personal injury or death in the event of an accidental deployment.
- Reconnect all SRS components (if previously disconnected).
- If previously directed to depower the SRS, repower the SRS. Do notprove out the SRS at this time. Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: Self Test - RCM.
- Are any RCM DTCs retrieved indicating a fault?
Yes
Do not clear any DTCs until all DTCs have been resolved. GO to the DTC Chart for pinpoint test direction. Diagnostic Trouble Code Tests and Associated Procedures
No
CLEAR all RCM CMDTCs. PROVE OUT the SRS. Repair is complete. RETURN the vehicle to the customer.
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