GM S10/S15/Sonoma Pick-Ups 1982-1993 Repair Manual

Back-Up Light/Neutral Safety Switch

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REMOVAL & INSTALLATION



Automatic Transmission

The back-up light switch on automatic transmission vehicles also acts as the neutral safety switch. The switch will activate the reverse lights when the gear shift lever is placed in the Reverse position, and it will prevent the engine from starting unless the shifter is in Neutral or Park. The switch is mounted to the steering column on most vehicles covered by this manual. The MFI-Turbo uses a floor mounted shifter, therefore the switch is relocated under the center console on these vehicles.

COLUMN MOUNTED SWITCH

See Figures 1 and 2

Two type of switches are generally found on these vehicles. Some early models will be equipped with adjustable switches which are bolted into position. Most vehicles covered by this manual should be equipped with ratcheting self-adjusting switches.

  1. Disconnect the negative battery cable.
  2.  
  3. If necessary for access, remove the steering column insulator/filler panel for access to the switch.
  4.  
  5. Disengage the electrical harness connector from the switch.
  6.  
  7. Certain early model vehicles utilize a switch which is bolted in position. If equipped, remove the retaining bolts.
  8.  
  9. Remove the switch by grasping and pulling it straight out of the steering column jacket.
  10.  

To install:


Click image to see an enlarged view

Fig. Fig. 1: Installation and adjustment of the early model bolt-on back-up lamp/neutral safety switch

  1. If equipped with an early model switch which is bolted into position, the switch should be equipped with a gauge hole for adjustment. If equipped, loosely install the switch to the column and adjust following the procedures in the illustration.
  2.  
  3. Most vehicles covered by this manual utilize a self-adjusting (ratcheting) switch. To install:
    1. Align the actuator on the switch with the holes in the shift tube.
    2.  
    3. Set the parking brake and place the gear selector in Neutral.
    4.  
    5. Press down on the front of the switch until the tangs snap into the rectangular holes in the steering column jacket.
    6.  
    7. Adjust the switch by moving the gear selector to Park. The main housing and the housing back should ratchet, providing the proper switch adjustment.
    8.  

  4.  
  5. Engage the harness connector to the switch.
  6.  
  7. Connect the negative battery cable, then verify proper switch operation. Make sure the Reverse lights work and that the ignition will only work in the Neutral or Park positions. If necessary, readjust the switch. For ratcheting type switches, move the gear selector all the way to the Low position, then repeat the adjustment.
  8.  
  9. If applicable, install the steering column insulator/filler panel.
  10.  



Click image to see an enlarged view

Fig. Fig. 2: Ratcheting type back-up lamp/neutral safety switch mounting

FLOOR CONSOLE MOUNTED SWITCH

See Figure 3

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the center console for access to the switch assembly.
  4.  
  5. Disengage the switch electrical connector.
  6.  
  7. Remove the retaining nuts, then remove the switch from the vehicle.
  8.  
  9. If necessary, remove the gauge pin from the switch.
  10.  



Click image to see an enlarged view

Fig. Fig. 3: Back-up light/neutral safety switch mounting-MFI-Turbo

  1. If installing a new switch:
    1. Place the shift control lever in Neutral.
    2.  
    3. Align the carrier tang on the back-up lamp/neutral safety switch with the slot on the shifter.
    4.  

  2.  

Replacement switches are pinned in the Neutral position to ease installation. If the switch has been rotated or the switch is broken, install the switch using the "old switch'' installation and adjustment procedure.

  1. Tighten the switch retaining nuts to 30 inch lbs. (3.4 Nm), then engage the switch connector.
  2.  
  3. Move the shift control lever out of Neutral in order to shear the plastic pin, then remove the accessible piece(s) of the gauge pin.
  4.  

  1. If installing an old switch, install and adjust the switch to assure proper operation:
    1. Place the shift control lever in Neutral.
    2.  
    3. Align the carrier tang on the switch with the slot on the shifter.
    4.  
    5. Loosely install the retaining switch nuts and engage the wiring connector.
    6.  
    7. Rotate the switch to align the service adjustment hole with the carrier tang hold, then use a 0.09 in. (2.34mm) gauge pin to complete adjustment. Insert the pin in the service adjustment hole and rotate the switch until it drops to a depth of 0.59 in. (15mm). Hold the switch in this position and tighten the retaining nuts to 30 inch lbs. (3.4 Nm).
    8.  

  2.  
  3. Install the center console.
  4.  
  5. Connect the negative battery cable.
  6.  
  7. Verify proper switch operation.
  8.  

Manual Transmission

On manual transmissions, the back-up light switch is normally mounted to the transmission. The safety switch is replaced by a clutch switch which is mounted to the clutch pedal. For replacement procedures, please refer to Chapter 7 of this manual.

 
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