Pinpoint Tests AD: DTC C1946
Air Bag and Safety Belt Pretensioner Supplemental Restraint System (SRS)
Pinpoint Tests
Pinpoint Test AD: DTC C1946
Refer to Wiring Diagram Set 46, Supplemental Restraint System for schematic and connector information. Diagrams By Number
Lamp Fault Codes (LFCs)
The following Lamp Fault Code (LFC) indicates the specific fault associated with DTC C1946:
- LFC 4-9 - Front Driver's Seat Track Position Switch Circuit Open
Normal Operation
The seat track position sensor informs the Restraints Control Module (RCM) of the driver seat position. Refer to Air Bag and Safety Belt Pretensioner Supplemental Restraint System (SRS) Description and Operation.
The RCM monitors the driver seat track position sensor circuits. If the RCM detects an open circuit fault, it will store DTC C1946 in memory and flash a LFC 4-9 on the air bag warning indicator.
- DTC C1946 Driver Seat Track Position Sensor Circuit Open - If the RCM detects an open on the driver seat track position sensor circuit, 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 AD: DTC C1946
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.
WARNING: Never probe the electrical connectors on safety belt buckle/retractor pretensioners or adaptive load limiting retractors. Failure to follow this instruction may result in the accidental deployment of the safety belt pretensioners or adaptive load limiting retractors, which increases the risk of serious personal injury or death.
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: The Supplemental Restraint System (SRS) must be fully operational and free of faults before releasing the vehicle to the customer.
NOTE: 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.
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AD1 CHECK FOR ON-DEMAND AND CONTINUOUS DTCs
- Enter the following diagnostic mode on the scan tool: Self-Test - RCM.
- Was DTC C1946 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 AD2.
No
This is an intermittent fault when present as a continuous memory DTC only (DTC not retrieved on demand). The fault condition is not present at this time. GO to AD6.
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AD2 CHECK CIRCUIT 1520 (LG) FOR AN OPEN BETWEEN THE RCM AND DRIVER SEAT
- 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.
- Disconnect: RCM C310a and C310b.
- Measure the resistance between RCM C310b-23, circuit 1520 (LG), harness side and driver seat track position sensor C356-2, circuit 1520 (LG), harness side.
- Is the resistance less than 0.5 ohm?
Yes
GO to AD3.
No
REPAIR circuit 1520 (LG). GO to AD7.
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AD3 CHECK CIRCUIT 1558 (TN/BK) FOR AN OPEN BETWEEN THE RCM AND THE DRIVER SEAT
- Measure the resistance between RCM C310b-24, circuit 1558 (TN/BK), harness side and driver seat track position sensor C356-1, circuit 1558 (TN/BK), harness side.
- Is the resistance less than 0.5 ohm?
Yes
GO to AD4.
No
REPAIR circuit 1558 (TN/BK). GO to AD7.
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AD4 CHECK THE SEAT TRACK POSITION SENSOR
- Connect: RCM C310a and C310b.
- Install a known good driver seat track position sensor. Refer to Seat Position Sensor Service and Repair.
- Connect: 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.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: Self-Test - RCM.
- Was DTC C1946 retrieved on-demand during self-test?
Yes
GO to AD5.
No
Fault corrected. GO to AD7.
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AD5 CONFIRM THE RCM FAULT
NOTE: Make sure all Restraint System Diagnostic Service Tools, sensor electrical connectors and the RCM electrical connectors are connected before carrying out the self-test. If not, erroneous DTCs will be recorded.
- Ignition OFF.
- Depower the SRS. Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.
- Reinstall the original driver seat track position sensor.
- 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 C1946 retrieved on-demand during self-test?
Yes
INSTALL a new RCM. REFER to Restraints Control Module (RCM) Service and Repair. GO to AD7.
No
Fault corrected. GO to AD7.
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AD6 CHECK FOR AN INTERMITTENT FAULT
- Ignition OFF.
- Enter the following diagnostic mode on the scan tool: Self-Test - RCM.
- Was DTC C1946 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 AD2.
No
CHECK for causes of the intermittent fault. ATTEMPT to recreate the hard fault by flexing the wire harness and cycling the ignition key 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 AD7.
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AD7 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 self-test?
Yes
Do not clear any DTCs until all DTCs have been resolved. GO to the DTC Charts for pinpoint test direction. [1][2]Diagnostic Trouble Code Descriptions
No
CLEAR all RCM continuous memory DTCs. PROVE OUT the SRS. Repair is complete. RETURN the vehicle to the customer.
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