B1538 OBD-II Trouble Code: Memory 2 Switch Circuit Short To Ground

What the B1538 code means

A power drivers’ seat slides back and forth on a track and is powered by three motors: one for fore-and-aft, and two for vertical movement, tilting the front or rear of the seat. A separate motor controls the seat’s reclining range of motion. The motors receive voltage from the driver’s seat module, which reverses polarity to determine the seat’s movement. Each motor features a Hall-effect position sensor, which sends a signal pulse back to the DSM to store the position of the power seat and backrest.

The DSM will self-test if it detects an error in the circuit. If the error is sensed for two minutes or more, the DTC is set as continuous, and any input signal on the circuit will be ignored.

What causes the B1538 code?

• DSM failure
• Failed switch for power seats
• Failed wiring, connectors, terminals

What are the symptoms of the B1472 code?

Symptoms can include:

• Power seat won’t operate
• Power recliner won’t operate

How does a mechanic diagnose the B1538 code?

• Use the switches to operate the seat, mirrors, adjustable pedals (if equipped) and tilt steering through their full range of travel. Return them all to their central travel positions.
• Set your diagnostic tool’s mode to Self Test/DSM/Retrieve DTCs
• If your diagnostic tool shows code B1538, place the ignition key in ON position. Operate the gear selector through the entire range of gears and monitor parameter IDs (PIDs).
• If PIDs agree with factory spec, enter DataLogger/DSM PID: IGN_SW in your diagnostic tool.
• Cycle the ignition switch through OFF/ACC/RUN/START/ON while monitoring the PID states.
• If PIDs agree with factory spec, attempt to operate the power seat, power mirrors and adjustable pedals through their full range of travel.
• Return the seat, mirrors and pedals to their central travel positions.
• Enter Self Test/DSM/DTCs in the diagnostic tool. Retrieve the DTCs.
• Put the ignition key in OFF position. Disconnect memory SET switch C503 and measure resistance between memory SET switch pins (component side) as you press the switch buttons. Resistance should be less than 5 ohms.
• If the memory SET switch tests as bad, replace the switch. If PIDs are within spec, check the memory SET switch’s ground circuit, harness side and ground. If resistance is more than 5 ohms, repair the circuit, repeat the self-test and clear DTCs.
• If resistance is less than 5 ohms, check circuits CPS14, CPS15 and CPS16 for a short to voltage.
• With key in OFF position, disconnect DSM C341c. Turn key to ON and measure voltage between SET switch C503-2, C503-5 and C503-6, harness side and ground. If voltage is present, repair the affected circuit, repeat self-test and clear DTCs.
• If no voltage, check circuits CPS14, CPS15 and CPS16 for a short to ground. Resistances should be greater than 10K ohms. If not, repair the affected circuit, repeat self-test and clear DTCs.
• If resistance is greater than 10K ohms, check for open circuits on CPS14, CPS15 and CPS16.
• If resistances on these circuits are less than 5 ohms, install a new DSM, repeat self-test and clear DTCs. If not, repair the affected circuit.
• Enter DataLogger/DSM PIDs on your diagnostic tool. Operate the power seat, power mirrors and adjustable pedals through their entire range of motion. Monitor the PIDs, through each associated motor’s full range of travel. PIDs should indicate that the sensor is operational.
• If yes, replace the DSM. If no, check front height sensor circuits. Disconnect DSM C341b and Memory Seat Front Height Position Sensor C383, with key in ON position.
• If voltage is present, repair the affected circuit. If not, check front height sensor circuits VPS10 and RPS13 for short to ground, with key in OFF position. Resistances should be better than 10k ohms. If not, repair the affected circuit.
• If resistances are under 10k ohms, repair the affected circuit.
• If resistances are greater than 10k ohms, check front height sensor circuits VPS10 and RPS13 for an open condition. If resistances are less than 5 ohms, install a new driver seat track assembly. If greater than 5 ohms, repair the affected circuit.
• Check rear height sensor circuits RPS13 and VPS11 for a short to voltage. If voltage is present, repair the affected circuit.
• If no voltage is present, check rear height sensor circuits RPS13 and VPS11 for a short to ground. If resistance is under 10k ohms, repair the affected circuit.
• If resistance is over 10k ohms, check rear height sensor circuits RPS13 and VPS11 for an open condition. If resistance is less than 5 ohms, install a new seat track assembly.
• If resistance is greater than 5 ohms, repair the circuit.

Common mistakes when diagnosing the B1538 code

This is a code that requires careful and methodical process of elimination and diagnosis for a proper repair. Be careful not to skip over steps and jump to a hasty conclusion that could lead to replacing parts unnecessarily.

How serious is the B1538 code?

A B1538 code can result in power seats, mirrors, tilt wheel and adjustable pedals that are stuck in place and cannot be adjusted.

What repairs can fix the B1538 code?

• Door-mounted power seat/mirror switch replacement
• DSM replacement
• Seat track replacement
• Repair of wiring, terminals, and/or connectors

Additional comments for consideration regarding the B1538 code

Be certain to use the right DVOM probes while troubleshooting a B1538 code, to avoid damage or failure of parts.

Need help with a B1538 code?

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