• 2019

Seats Of Power – And How To Keep Them

The driver power lumbar is either a two-way rocker switch or a four-way switch. The rocker switch used on minivans moves the lumbar support in and out. The four-way switch, shown in Figure 1, can adjust the power lumbar support inward, outward, upward and downward for added driver comfort.

Figure 1 | Controls for power seats are located on the outboard seat cushion side shield of each front seat.

Problems With Power Seats

The most common problem with power seats results from damage to the outboard seat cushion side shield, usually from a person applying too much pressure to the area of the seat nearest the side shield. As such, the side shield can crack, displacing the switches and wiring. If a switch is displaced, the driver or passenger may not be able to reach it. Moreover, the switch wiring may get tangled with seat drive mechanisms and can be cut or otherwise damaged when the seat moves. Eventually, the wiring could be damaged to the point where the seat will no longer move.

Specific Switch Problems

If the seat fails to move when the switch is pressed, it may produce a diagnostic trouble code (DTC), two of which are seat-specific.

Code: B1D5E-13-Power Seat Switch-Circuit Open

Power seats have a Memory Seat Module (MSM) controlling the operation of the power seat, including setting and recalling memory seat and steering positions. Pressing the memory switch button sends a signal from the switch to the Driver Door Module (DDM) via a mux signal circuit. The DDM will then request the MSM perform the function via the CAN bus circuit.

When the SET button on the memory switch is pressed, followed by pressing 1 or 2, the MSM will store the current seat and steering position. Afterward, when pressing 1 or 2, the MSM recalls that particular seating position. The fault code is set when the MSM detects an open in the seat switch mux circuit.

Using the appropriate scan tool, read the active DTCs. If the B1D5E-13-Power Seat Switch-Circuit Open code is present, turn the ignition off and disconnect the driver seat switch harness connector. Measure the resistance between ground and the (P28) driver seat switch mux return circuit.

If the resistance is below 40 ohms, check the (P311) driver seat front vertical/recliner switch mux circuit.

Disconnect the MSMD C7 harness connector. Measure the resistance between the (P311) driver seat switch mux circuit and the (P28) driver seat switch mux return circuit. If the resistance is between 40 and 60 ohms, check the (P309) driver seat rear vertical/horizontal switch mux circuit. If the resistance between the (P309) driver seat rear vertical/ horizontal switch mux circuit and the (P28) driver seat switch mux return circuit is between 40 and 60 ohms, there is probably an issue with the MSM.

If the resistance is not between 40 and 60 ohms, check the (P309) driver seat rear vertical/horizontal switch mux circuit for an open or excessive resistance. If the resistance is above 10 ohms, repair the open or excessive resistance issue. If the resistance is less than 10 ohms, replace the driver seat switch.

If the (P28) driver seat switch mux return circuit resistance is not below 40 ohms, check the circuit for an open or excessive resistance. Disconnect the MSM C7 harness connector.

Measure the resistance between the (P28) driver seat switch mux return circuit between the driver seat switch harness connector and the MSM harness connector. If the resistance is above 10 ohms, repair the open or excessive resistance issue. If the resistance is below 10 ohms, there’s an issue with the MSM.

Code: B1D62-2A Power Seat Switch Stuck-Stuck

This code is set when the memory seat module (MSM) detects that the driver seat switch is an active position for longer than 50 seconds. To check to see if this problem exists, turn the ignition on, record and erase the DTCs, then cycle the driver seat switch in all directions several times. Wait one minute. Read the active DTCs. If the fault code appears again, replace the driver seat switch.

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