Diagnostic Procedure

WARNING: This page is about a different car, the 2020 Mazda CX-30. However, it is still accessible from the selected car via links, so may be relevant.

When performing an asterisked (*) troubleshooting inspection, shake the wiring harness and connectors while performing the inspection to discover whether poor contact points are the cause of any intermittent malfunctions. If there is a problem, check to make sure connectors, terminals and wiring harnesses are connected correctly and undamaged.

TEMPERATURE FOR HEATED STEERING WHEEL SYSTEM CANNOT BE STABLE [HEATED STEERING WHEEL] DIAGNOSTIC PROCEDURE

Step	Inspection	Results	Action
1*	INSPECT HEATED STEERING WHEEL UNIT CONTROL CIRCUIT FOR OPEN CIRCUIT WARNING: Handling the component parts improperly can accidentally operate (deploy) the air bag module, which may seriously injure you. Read the service warnings/cautions and the workshop service information before handling the air bag system components. (See AIR BAG SYSTEM SERVICE WARNINGS [TWO-STEP DEPLOYMENT CONTROL SYSTEM - US/CANADA SPEC.] .) (See AIR BAG SYSTEM SERVICE CAUTIONS [TWO-STEP DEPLOYMENT CONTROL SYSTEM - US/CANADA SPEC.] .) Switch the ignition off. Disconnect the negative battery terminal and wait for 1 min or more. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Inspect the applicable circuit for an open circuit. (See CIRCUIT INSPECTION .) Is the circuit normal?	Yes	Go to the next step.
1*		No	Replace the steering wheel and perform the repair completion verification. (See STEERING WHEEL AND COLUMN REMOVAL/INSTALLATION (US) .)
2*	INSPECT HEATED STEERING WHEEL UNIT THERMISTOR SIGNAL CIRCUIT FOR OPEN CIRCUIT Inspect the applicable circuit for an open circuit. (See CIRCUIT INSPECTION .) Is the circuit normal?	Yes	Replace the heated steering wheel control unit and perform the repair completion verification. (See HEATED STEERING WHEEL CONTROL UNIT REMOVAL/INSTALLATION .)
2*		No	Replace the steering wheel and perform the repair completion verification. (See STEERING WHEEL AND COLUMN REMOVAL/INSTALLATION (US) .)
Repair completion verification	VERIFY IF MALFUNCTION CAUSE IS CORRECTED Connect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .) Switch the ignition ON (engine off or on). Operate the heated steering wheel switch to turn on the heated steering wheel system. Does the heated steering wheel system operate normally?	Yes	Troubleshooting completed. (Explain the contents of the servicing to the customer.)
Repair completion verification		No	Verify the malfunction symptom in the symptom troubleshooting chart and perform the other applicable malfunction diagnosis. (See SYMPTOM TROUBLESHOOTING [HEATED STEERING WHEEL] .)