Power Seat Malfunction (Without Memory)
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Power Seat Malfunction (Without Memory)
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Diagnostic Fault Information
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Circuit
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Short to Ground
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Open/High Resistance
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Short to Voltage
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Signal Performance
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Seat Adjuster Switch B+
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1
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1
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-
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-
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Front Vertical Motor Down Control
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1
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1
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-
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-
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Front Vertical Motor Up Control
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1
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1
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-
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-
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Horizontal Motor Forward Control
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1
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1
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-
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-
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Horizontal Motor Rearward Control
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1
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1
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-
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-
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Rear Vertical Motor Down Control
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1
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1
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-
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-
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Rear Vertical Motor Up Control
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1
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1
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-
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-
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Recline Motor Forward Control
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1
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1
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-
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-
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Recline Motor Rearward Control
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1
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1
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-
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-
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Seat Adjuster Switch Ground
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-
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1
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-
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-
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1. Power seat inoperative
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Circuit/System Description
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The driver seat without memory and the passenger seat are completely controlled through their respective seat adjuster switch. Battery voltage is supplied at all times to the seat switch through a 25 A circuit breaker located in the instrument panel fuse block. When the seat switches are in an inactive state, the switch contacts are closed to the switch B+ circuit.
All seat motors are reversible. For example, when the seat horizontal forward switch is pressed to move the entire seat forward, ground is applied through the switch contacts and the seat horizontal motor forward control circuit to the motor. With the horizontal motor rearward switch contacts closed to the switch B+ circuit, the motor runs in order to drive the entire seat forward until the switch is released. Moving the entire seat rearward works similarly to moving the entire seat forward, except that battery voltage and ground are applied on opposite circuits causing the motor to run in the opposite direction. All seat motors are powered this way.
Schematic Reference
Connector End View Reference
Component Connector End Views
Description and Operation
Power Seats System Description and Operation
Electrical Information Reference
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Circuit/System Verification
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Operate the appropriate driver or passenger switches for the seat directional motors listed below in both directions. The seat should move in the commanded direction.
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•
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M50 front vertical motor
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•
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M55 rear vertical motor
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S64 Seat Switch Circuit Test
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1.
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Ignition OFF, disconnect the harness connector at the appropriate S64 seat adjuster switch.
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2.
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Test for less than 5 Ω between the appropriate ground circuit terminal listed below and ground:
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•
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8-way power seat terminal B
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•
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2-way power seat terminal A and terminal C
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3.
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If greater than the specified range, test the ground circuit for an open/high resistance.
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4.
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Ignition ON, verify that a test lamp illuminates between the appropriate B+ circuit listed below and ground:
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•
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8-way power seat terminal E
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•
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2-way power seat terminal D
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5.
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If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
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6.
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If all circuits test normal, test or replace the S64 seat adjuster switch.
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Seat Adjuster Motor Circuit Test
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1.
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Ignition OFF, disconnect the harness connector at the appropriate seat motor listed below:
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•
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M50 seat front vertical motor
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•
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M55 seat rear vertical motor
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•
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M51 seat horizontal motor
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2.
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Connect a test lamp between control circuit terminal 1 and control circuit terminal 5.
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3.
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Ignition ON, command the seat motor Up and Down or Forward and Rearward using the seat switch. The test lamp should turn ON when commanding the up and down or forward and rearward states.
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4.
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If the test lamp remains OFF for either of the commands, test the control circuits for a short to ground or an open/high resistance. If the circuits test normal, test or replace the S64 seat adjuster switch.
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5.
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If all circuits test normal, test or replace the seat motor.
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Seat Switch Test
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1.
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Ignition OFF, disconnect the harness connector at the S64 seat adjuster switch.
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2.
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Test for infinite resistance between the ground terminal and each control terminal with the switch in the open position.
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3.
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If less than the specified value, replace the S64 seat adjuster switch.
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4.
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Test for less than 1 Ω between the ground terminal and each control terminal with the appropriate switch in the closed position.
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5.
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If greater than the specified range, replace the S64 seat adjuster switch.
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6.
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Test for less than 1 Ω between the B+ terminal and each control terminal with the switch in the open position.
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7.
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If greater than the specified range, replace the S64 seat adjuster switch.
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Seat Motor
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1.
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Ignition OFF, disconnect the harness connector at the appropriate seat motor listed below:
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•
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M50 seat front vertical motor
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•
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M55 seat rear vertical motor
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•
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M51 seat horizontal motor
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2.
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Note
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When performing the following tests, make sure that the seat is not already in the position the test is attempting to produce.
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Install a 30 A fused jumper wire between control terminal 1 and 12 V. Momentarily install a jumper wire between control terminal 5 and ground. The seat motor should momentarily perform the appropriate FORWARD/REARWARD/UP/DOWN function.
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3.
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If the function does not perform as specified, replace the seat motor.
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4.
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Reverse the polarity of jumper wires. The a seat motor should perform in the opposite direction.
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5.
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If the function does not perform as specified, replace the seat motor.
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Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
