Pinpoint Test: Seat Heater Mat
- Check for DTC's
Where possible use the manufacturer approved diagnostic system to review any logged seat heater mat DTC's
Were any seat heater mat DTC's logged?
YES: Carry out the help text action for any logged DTC's. Clear the DTC and retest. If DTC's return follow the tests listed below Go to step 2.
NO: Go to step 2.
- Manual Check NOTE: On full power the seat should be hot to touch
If required operate the vehicle air conditioning on full for 10 minutes to reduce the in vehicle ambient temperature
Operate the seat heater on full power
Does the seat heater operate correctly?
YES: Clear any stored DTC's and retest. If seat heater operation is correct no further action required
NO: Go to step 3.
- Short Circuit To Ground
Refer to the electrical circuit diagrams and the seat heater mat application chart (see above) to identify the connector
Disconnect the conSSnector
Refer to the electrical circuit diagrams and check the seat heater mat (heater circuit) and (thermal sensor circuit) for short circuit to ground
Are either of the circuits short circuit to ground?
YES: Repair the circuit or replace the seat heater mat as required. Refer to the warranty policy and procedures manual, or determine if any prior approval programme is in operation, prior to the installation of a new module/component. Clear any stored DTC's and retest
NO: Go to step 4.
- Circuit Continuity Test
Refer to the electrical circuit diagrams and check the seat heater mat (heater circuit) for circuit continuity
Does the seat heater mat heater circuit pass the continuity test?
YES: Go to step 5.
NO: Repair the circuit or replace the seat heater mat as required. Refer to the warranty policy and procedures manual, or determine if any prior approval programme is in operation, prior to the installation of a new module/component. Clear any stored DTC's and retest
- Power Consumption NOTE: The seat heater power supply cycles on and off dependent on the seat and cabin temperature and may only switch on for 5 seconds in 30 seconds
Reconnect the connector
Operate the vehicle air conditioning on full for 10 minutes to reduce the in vehicle ambient temperature
Refer to the electrical circuit diagrams and check the seat heater mat (heater circuit) using a current clamp
Operate the seat heater on full power
Use the chart above to calculate typical value (V/R=I) (Volts divided by Resistance equals Current in Amps )
Examples (12 volts / 0.5 ohms =24 amps) (12 volts / 1 ohms = 12 amps) (12 volts / 2 ohms = 6 amps)
Does the seat heater mat consume the correct level of current?
YES: Clear any stored DTC's and retest. If operation correct, no further action required
NO: Go to step 6.
- Resistance Check NOTE: Ensure the multimeter used is calibrated and a resistance reading of 0 ohms is shown when the test leads are connected together, alternately subtract any resistance shown from the resultNOTE: The seat heater mat circuits should be checked at the seat heater module connectorNOTE: Refer to the electrical circuit diagrams and to confirm the total resistance of the circuit the cushion and backrest are connected in series
Refer to the electrical circuit diagrams and the seat heater mat application chart (see above) to identify the terminals
Disconnect the connector
Using a multimeter, carry out a resistance check of the seat heater mat heater circuit and the NTC resistor circuit . Record the results
Compare the results to the chart (see above)
Are the results within specification at the given ambient temperature? (tolerance +/- 0.5 Ohms)
YES: Reconnect the connector. Clear any stored DTC's and retest. If customer concern or DTC's return refer to electrical circuit diagrams and investigate the power and ground supply circuits
NO: Replace the seat heater mat as required. Refer to the warranty policy and procedures manual, or determine if any prior approval programme is in operation, prior to the installation of a new module/component. Clear any stored DTC's and retest