Pinpoint Test S: DTC C1948
Air Bag and Safety Belt Pretensioner Supplemental Restraint System (SRS)
Pinpoint Tests - Restraints Control Module (RCM)
Pinpoint Test S: DTC C1948
Refer to Wiring Diagram Set 46, Supplemental Restraint System for schematic and connector information. Diagrams By Number
NOTE: Due to the seat track position sensor being a Hall-effect type sensor, this pinpoint test will be diagnosing a current out of range fault instead of the current DTC definition for a resistance out of range fault.
Normal Operation
The driver seat is equipped with a seat track position sensor. The seat track position sensor is comprised of integrated circuits called Hall-effect switch. The seat track position sensor indicate to the Restraints Control Module (RCM) the position of the driver seat, forward or rearward.
The RCM supplies current to the seat track position sensor. Current flows through the switch, both in the forward or rearward seat position to ground. The RCM will sense the difference in this current draw, 6 mA (forward) or 15 mA (rearward), and use this information in determining the deployment rate of the dual-stage driver air bag module. If the RCM detects current out of range, it will set a DTC.
If the RCM detects a current out of range condition, it will store DTC C1948 in memory and send a message to the Instrument Cluster (IC) module to illuminate the air bag warning indicator.
- DTC C1948 Front Driver's Seat Track Position Switch Circuit Resistance out of Range - If the RCM detects a current out of range between forward and rearward on the driver seat track position switch, it will set this DTC.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Driver seat track position sensor
- RCM
PINPOINT TEST S: DTC C1948
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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S1 RETRIEVE RCM DTCs
- Enter the following diagnostic mode on the scan tool: Self Test - RCM .
- Was DTC C1948 retrieved on-demand during self-test?
Yes
The fault condition is still present. This fault cannot be cleared until it is corrected and the DTC is no longer retrieved during the on-demand self test. GO to S2.
No
This is an intermittent fault when present as a Continuous Memory Diagnostic Trouble Code (CMDTC). The fault condition is not present at this time. GO to S4.
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S2 CHECK DRIVER SEAT TRACK POSITION SENSOR FOR A FAULT STATUS CHANGE (RESISTANCE OUT OF RANGE INDICATED)
NOTE: This pinpoint test step will attempt to change the fault reported by the RCM by inducing a different fault condition. If the fault reported changes, this indicates the RCM is functioning correctly and is not the source of the fault.
- Ignition OFF.
- Depower the SRS. Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.
- Disconnect: Driver Seat Track Position Sensor C356.
- Connect a fused jumper wire between driver seat track position sensor C356-2, circuit RR137 (BU/GY), harness side and C356-1, circuit GD127 (BK/BU), harness side.
- 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.
- Enter the following diagnostic mode on the scan tool: Self Test - RCM .
- DIAGNOSTIC TIP: When viewing on-demand DTCs with the driver seat track position sensor circuits shorted together, a short to ground fault would normally be retrieved.
- Did the on-demand DTC change from C1948 to C1947?
Yes
INSTALL a new driver seat track position sensor. REFER to Seat Position Sensor Service and Repair. GO to S5.
No
GO to S3.
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S3 CONFIRM RCM FAULT
- Ignition OFF.
- Depower the SRS. Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.
- Remove the fused jumper wire from the driver seat track position sensor.
- Connect: Driver Seat Track Position Sensor C356.
- 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.
- Enter the following diagnostic mode on the scan tool: Self Test - RCM .
- Was DTC C1948 retrieved on-demand during self-test?
Yes
INSTALL a new RCM. REFER to Restraints Control Module (RCM) Service and Repair. GO to S5.
No
In the process of diagnosing the fault, the fault condition has become intermittent. CHECK for causes of the intermittent fault in the areas previously worked in, particularly the pins and terminals of electrical connectors that were disconnected. ATTEMPT to recreate the hard fault by flexing the wire harness and cycling the ignition 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 S5.
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S4 CHECK FOR AN INTERMITTENT FAULT
- Ignition OFF.
- Depower the SRS. Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.
- Disconnect: Driver Seat Side Air Bag Module C328.
- 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.
- Enter the following diagnostic mode on the scan tool: Self Test - RCM.
- Was DTC C1948 retrieved on-demand during self-test?
Yes
The fault condition is now present. This fault cannot be cleared until it is corrected and the DTC is no longer retrieved during the on-demand self test. GO to S2.
No
The fault is not present and cannot be recreated at this time.
CHECK for causes of the intermittent fault. ATTEMPT to recreate the hard fault by flexing the wire harness and cycling the ignition 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 S5.
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S5 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 - Restraints.
- NOTE: When selecting Restraints from the Self Test menu, DTCs will be retrieved from the RCM and OCSM.
- Are any RCM and/or Occupant Classification System Module (OCSM) DTCs retrieved indicating a fault?
Yes
Do not clear any DTCs until all DTCs have been resolved. GO to the DTC Charts for pinpoint test direction. Diagnostic Trouble Code Tests and Associated Procedures
No
CLEAR all RCM and OCSM DTCs. PROVE OUT the SRS. Repair is complete. RETURN the vehicle to the customer.
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