SECTION 8-C 1959 BUICK POWER SEAT CIRCUIT AND TROUBLE DIAGNOSIS

8-3 1959 BUICK POWER SEATS

Before performing an extensive checking procedure to locate an electrical failure, check the seat actuators and seat adjusters for mechanical failure and check the attachment of ground wire at the rear end of the right adjuster. In addition, study the seat circuit diagrams to become familiar with the seat circuit.

It may be necessary to use only one or all of the procedures outlined to locate an electrical failure in the circuit, depending on the nature of the failure. If the location of the failure is evident, follow only the step outlined to check the affected wire or component. If the location of the failure is not evident, follow the procedure as outlined.

The six-way seat incorporates a separate 12 volt D.C. split series motor with an internal circuit breaker and self-locking gear drive for each of the three basic movements of the seat:

  1. Vertical movement of front edge of seat.
  2. Vertical movement of rear edge of seat.
  3. Horizontal movement of the seat.

The location of the motors and seat wiring harness is shown in Figure 8-16.

1959 Buick Six-Way Seat Wiring Harness Installation

1959 Buick Six-Way Seat Wiring Harness Installation

The 1959 Buick seat control switch is located in the left lower seat side panel. When the front button of the seat control switch is pushed up or down, current flows to the up or down field of the vertical motor which controls the movement of the front edge of the seat. The rear button controls the vertical movement of the rear edge of the seat. and the center button controls the horizontal movement of the seat assembly and also the vertical movement of the front and rear edge of the seat simultaneously. See Figure 8-17 for the six-way seat circuit diagram.

1959 Buick Six-Way Seat Circuit

1959 Buick Six-Way Seat Circuit

Checking For Current at 1959 Buick Seat Control Switch

  1. Remove seat adjuster switch to expose terminal block. With light tester check for current at terminal No. 1 shown in the circuit diagram Figure 8-17.
  2. If tester does not light and the 1959 Buick power windows are operative, there is an open or short circuit between the feed from the left door power window harness and the seat switch block. Check feed connector beneath left side of seat for proper connection.

Checking 1959 Buick Seat Control Switch

  1. To determine whether the seat failure is due to an inoperative switch, use a switch which has been checked for proper operation or obtain a No. 12 gauge jumper wire; then insert one end into the No. 1 (feed) terminal and the other end into each of the other terminal locations to actuate the seat motors. See Figure 8-17 for the function of each terminal location. The jumper wire may be used in the same manner as shown in Figure 8-12 for the window control switch. The switch locations to be connected to obtain a specific movement of the seat are listed below:
    • To raise front edge of seat, connect jumper in locations 1 and 7.
    • To lower front edge of seat, connect jumper in locations 1 and 2.
    • To raise rear edge of seat, connect jumper in locations 1 and 5.
    • To lower read edge of seat, connect jumper in locations 1 and 3.
    • To operate seat forward, connect jumper in locations 1 and 6.
    • To operate seat rearward, connect jumper in locations 1 and 4.
    • To raise front and rear edge of seat simultaneously, connect jumper in locations 1, 7 and 5.
    • To lower front and rear edge of seat simultaneously, connect jumper in locations 1, 2 and 3.
      NOTE: It will be necessary to use a three way jumper wire to energize the three locations specified in steps g and h.
  2. If all of the seat motors operate satisfactorily with the jumper wire or the new switch, but do not operate with the original switch, it is defective.

Checking the Wires Between the Seat Control Switch and Seat Motors

  1. Disengage harness connectors from seat motors and use light tester at end of wire being checked; then actuate control switch to energize wire being checked.
  2. If tester does not light, there is no current at end of wire. Failure is caused by an open or short circuit between end of wire and switch.
  3. Check the remaining wires in a similar manner.

Checking the 1959 Buick Seat Motors

  1. Disengage harness connector from motor being tested, and check attachment of ground wire at rear of right adjuster.
  2. Connect one end of a No. 12 gauge jumper wire to the power source and the other end to one of the motor terminals. Motor should operate. Check the remaining motor terminal in the same manner.

Typical Failures

Condition:

None of the seat adjuster motors operate.

Cause:

  • Open or short circuit in feed wire to control switch.
  • Defective control switch or incomplete ground circuit to switch.

Correction:

  • Check feed wire to switch for open or short circuit.
  • Check operation of switch.
  • Check ground wire attachment.

Condition:

Two of the three seat motors operate satisfactorily, one seat motor does not operate.

Cause:

  • Defective motor.
  • Open or short circuit in harness wiring from control switch to affected motor.

Correction:

  • Check the motor operation with jumper wire.
  • Check affected seat harness leads for short or open circuit.

1959 Buick Electric Horizontal Seat Circuit

The electric horizontal seat control switch is located in the left seat lower side panel. The seat motor is located near the center of the seat bottom frame as shown in Figure 8-15.

1959 Buick Electric Horizontal Seat Wiring Installation

1959 Buick Electric Horizontal Seat Wiring Installation

See Figure 8-14 for circuit diagram of electric horizontal seat.

1959 Buick Electric Horizontal Seat Circuit

1959 Buick Electric Horizontal Seat Circuit

Typical Failures

Condition:

The seat motor does not operate in either the forward or rearward direction.

Cause:

  • Open or short circuit in feed harness.
  • Inoperative motor.

Correction:

  • Check for current at seat control switch block. If current is not present check feed connectors beneath left side of front seat.
  • Check operation of seat control switch with jumper wire. See “Checking Door Window Control Switch” for similar operation.
  • Check circuit from control switch to motor for short or open circuit, and check ground wire.
  • Check operation of motor with No. 12 gauge jumper wire. Connect one end of jumper wire to power source and the other end to one of the seat motor terminals. Motor should operate. Perform same check at the other motor terminal. If motor does not operate, repair or replace motor as required.

Condition:

The seat motor operates in only one direction.

Cause:

  • Defective switch.
  • Open or short circuit in motor feed wires.
  • Defective seat motor.

Correction:

  • Check operation of seat control switch with jumper wire.
  • Check circuit from control switch to motor for short or open circuit.
  • Check operation of motor with No. 12 gauge jumper wire. Connect one end of jumper wire to power source and the other end to one of the seat motor terminals. Motor should operate. Perform same check at the other motor terminal. If motor does not operate, repair or replace motor as required.