Pinpoint Test E: LFC18/DTC B1890
Air Bag and Safety Belt Pretensioner Supplemental Restraint System (SRS)
Pinpoint Tests
Pinpoint Test E: LFC18/DTC B1890
Refer to Wiring Diagram Set 46, Supplemental Restraint System for schematic and connector information. Diagrams By Number
Normal Operation
When the ignition is in the ON position, the Passenger Air Bag Deactivation (PAD) indicator prove-out period is initiated by the Restraints Control Module (RCM). The RCM briefly activates the PAD indicator by supplying a ground on the indicator circuit to verify operation. Refer to Air Bag and Safety Belt Pretensioner Supplemental Restraint System (SRS) Description and Operation.
If the RCM detects a short to battery on the PAD warning lamp circuit, it will store DTC B1890 in memory and flash Lamp Fault Code (LFC) 18 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, it will set this DTC.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- PAD indicator
- RCM
PINPOINT TEST E: LFC 18/DTC B1890
WARNING: Remove restraint system diagnostic tools from the vehicle prior to road testing. If tools are not removed, the supplemental restraint system (SRS) device may not deploy in a crash. Failure to follow this instruction may result in serious personal injury or death in a crash and possibly violate vehicle safety standards.
WARNING: Never probe the electrical connectors on air bag, Safety Canopy(R) or side air curtain modules. Failure to follow this instruction may result in the accidental deployment of these modules, which increases the risk of serious personal injury or death.
NOTICE: Use the correct probe adapter(s) from the Flex Probe Kit when making 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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E1 RETRIEVE RCM DTCs
- Enter the following diagnostic mode on the scan tool: Self Test - RCM.
- Was RCM DTC B1890 retrieved on-demand during the self test?
Yes
GO to E2.
No
This is an intermittent fault when present as a CMDTC only. The fault condition is not present at this time. GO to E4.
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E2 CHECK CIRCUIT 1632 (TN/LB) 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: PAD Indicator C2039.
- 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 indicator C2039-2, circuit 1632 (TN/LB), harness side and ground.
- Is any voltage present?
Yes
REPAIR circuit 1632 (TN/LB). GO to E5.
No
GO to E3.
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E3 CHECK THE RCM
- Enter the following diagnostic mode on the scan tool: Self Test - RCM.
- NOTE: DTC B1884 should be retrieved when carrying out the on-demand self test due to an open on circuit 1632 (TN/LB), DTC B1890 should not be retrieved at this time.
- Was RCM DTC B1890 retrieved on-demand during the self test?
Yes
INSTALL a new RCM. REFER to Restraints Control Module (RCM) Service and Repair. GO to E5.
No
INSTALL a new PAD Indicator. REFER to Passenger Air Bag Deactivation (PAD) Indicator Service and Repair.
GO to E5.
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E4 CHECK FOR AN INTERMITTENT FAULT
- Enter the following diagnostic mode on the scan tool: Self Test - RCM.
- Was RCM DTC B1890 retrieved on-demand during the self test?
Yes
GO to E2.
No
CHECK for causes of intermittent short to battery on circuit 1632 (TN/LB). ATTEMPT to recreate the hard fault by flexing the wire harness and cycling the ignition frequently. ACTIVATE other systems in the same wire harness. 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 E5.
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E5 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 on-demand during the self test?
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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