Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Diagnostic Test
- TEST FOR INTERMITTENT CONDITION NOTE:
Make sure the battery is fully charged and the charging system is operating properly before proceeding.
- Turn the ignition on.
- Using a scan tool, record and erase Diagnostic Trouble Codes (DTCs).
- Turn the ignition off.
- Start the engine and let it run.
- Using a scan tool, read DTCs.
Is the DTC active?
Yes
- Go To 2
No
- The conditions that caused this code to set are not present at this time. Verify seat harness is routed correctly to the HSM. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors. Look for chafed, pierced, pinched, or partially broken wires and broken, bent, pushed out, spread, corroded, or contaminated terminals. Attempt to reproduce condition by operating all HSM functions one at a time, except for the Left Rear Heated Seat. Attempt to reproduce condition by adjusting the front seat.
- Perform the BODY VERIFICATION TEST. Refer to STANDARD PROCEDURE .
- CHECK (P177) LEFT REAR SEAT HEATER CONTROL CIRCUIT FOR A SHORT TO VOLTAGE
Courtesy of CHRYSLER GROUP, LLC
- Turn the ignition off.
- Disconnect the HSM C3 harness connector.NOTE:
Check connectors. Clean and repair as necessary.
- Start the engine and let it run.
- Measure the voltage of the (P177) Left Rear Seat Heater Control circuit between the HSM C3 harness connector and ground.
Is there any voltage present?
Yes
- Go To 3
No
- Go To 4
- CHECK (P177) LEFT REAR SEAT HEATER CONTROL CIRCUIT FOR A SHORT TO THE (F931) FUSED IGNITION RUN CONTROL OUTPUT CIRCUIT Fig 2: Checking Left Rear Seat Heater Control Circuit For Short To Fused Ignition Run Control Output Circuit
Courtesy of CHRYSLER GROUP, LLC
- Turn the ignition off.
- Measure the resistance between the (P177) Left Rear Seat Heater Control circuit and the (F931) Fused Ignition Run Control Output circuit at HSM C3 harness connector.
Is the resistance below 10K Ohms?
Yes
- Repair the (P177) Left Rear Seat Heater Control circuit for a short to the (F931) Fused Ignition Run Control Output circuit.
- Perform the BODY VERIFICATION TEST. Refer to STANDARD PROCEDURE .
No
- Repair the (P177) Left Rear Seat Heater Control circuit for a short to voltage.
- Perform the BODY VERIFICATION TEST. Refer to STANDARD PROCEDURE .
- CHECK (P177) LEFT REAR SEAT HEATER CONTROL CIRCUIT FOR A SHORT TO VOLTAGE DURING SEAT ADJUSTMENT
Courtesy of CHRYSLER GROUP, LLC
- Measure the Voltage of the (P177) Left Rear Seat Heater Control circuit between the HSM C3 harness connector and ground while adjusting the front seat.
Is there any Voltage present during the seat adjustment?
Yes
- Repair the (P177) Left Rear Seat Heater Control circuit for a short to voltage.
- Perform the BODY VERIFICATION TEST. Refer to STANDARD PROCEDURE .
No
- Go To 5
- Measure the Voltage of the (P177) Left Rear Seat Heater Control circuit between the HSM C3 harness connector and ground while adjusting the front seat.
- CHECK (P177) LEFT REAR SEAT HEATER CONTROL CIRCUIT FOR A SHORT TO THE (P178) RIGHT REAR SEAT HEATER CONTROL CIRCUIT Fig 4: Checking Left Rear Seat Heater Control Circuit For Short To Right Rear Heater Control Circuit
Courtesy of CHRYSLER GROUP, LLC
- Turn the ignition off.
- Disconnect the Left or Right Rear Seat Cushion Heater harness connector.
- Measure the resistance between the (P177) Left Rear Seat Heater Control circuit and the (P178) Right Rear Seat Heater Control circuit at HSM C3 harness connector.
Is the resistance below 10K Ohms?
Yes
- Repair the (P177) Left Rear Seat Heater Control circuit for a short to the (P178) Right Rear Seat Heater Control circuit.
- Perform the BODY VERIFICATION TEST. Refer to STANDARD PROCEDURE .
No
- Replace the Heated Seat Module (HSM) in accordance with the Service Information. Refer to MODULE, HEATED SEAT, REMOVAL .
- Perform the BODY VERIFICATION TEST. Refer to STANDARD PROCEDURE .
NO RELATED
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.