Circuit/System Testing
- Ignition OFF, disconnect the MSM connector X1.
- Verify less than 15 ohms of resistance through the seat back heater element from the voltage supply circuit terminal to the low side drive control circuit terminal in the harness connector.
- If the resistance is greater than 15 ohms test the supply and control circuits for an open/high resistance. If the circuits test normal replace the seat back heater element.
- Disconnect the MSM connectors X2 and X5.
- Verify the resistance through the seat back heat sensor is 850-300K ohms from the signal circuit terminal to the low reference circuit terminal in the harness connectors.
- If greater than 300K ohms, test the signal circuit and low reference circuit for an open/high resistance. If the circuits test normal, replace the seat back heater element.
- If less than 850 ohms, replace the seat back heater element.
- Connect the MSM connectors X1, X2, and X5.
- Disconnect the seat back heater element connector.
- Ignition ON, verify that the heat sensor signal circuit voltage from the MSM is not greater than 5 volts.
- If the signal circuit is greater than 5 volts test for a short to voltage. If the circuit tests normal replace the MSM.
- If the circuits test normal replace the seat back heater element.