GM Blazer/Jimmy/Typhoon/Bravada 1983-1993 Repair Guide

Component Replacement

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SYSTEM FILLING



The master cylinder reservoirs must be kept properly filled to prevent air from entering the system. No special filling procedures are required because of the anti-lock system.

When adding fluid, use only DOT 3 fluid; the use of DOT 5 or silicone fluids is specifically prohibited. Use of improper or contaminated fluid may cause the fluid to boil or cause the rubber components in the system to deteriorate. Never use any fluid with a petroleum base or any fluid which has been exposed to water or moisture.

EHCU/BPMV VALVE



See Figure 1

The EHCU/BPMV valve is not serviceable and must never be disassembled or repaired. If tests indicate the unit is faulty, the entire assembly must be replaced.

  1. Tag and disconnect the brake lines from the EHCU/BPMV. Immediately cap or plug all openings to prevent system contamination or excessive fluid loss.
  2.  
  3. Tag and disengage the electrical connectors from the EHCU/BPMV.
  4.  



Click image to see an enlarged view

Fig. Fig. 1: Typical EHCU/BPMV brake pipe connections - ALWAYS tag the connections to assure proper installation

  1. Remove the retainers holding the EHCU/BPMV upper bracket to the lower bracket and vehicle. Remove the upper bracket and hydraulic unit as an assembly.
  2.  
  3. If necessary, once they are removed from the vehicle, separate the bracket from the EHCU/BPMV.
  4.  

To install:
  1. If removed, assemble the EHCU/BPMV to its bracket. Install the retainers and tighten to 84 inch lbs. (9 Nm). Be careful as overtightening these bolts can cause excessive noise transfer during system operation.
  2.  
  3. Install the assembly into the vehicle, then tighten the retainers to 20 ft. lbs. (27 Nm).
  4.  
  5. Engage the electrical connectors as tagged during removal. Make certain each is squarely seated and secure.
  6.  
  7. Remove the caps or plugs, then connect the brake lines to their original locations, as tagged during removal. Tighten the fittings to 16 ft. lbs. (22 Nm) for the Typhoon or to 21 ft. lbs. (29 Nm) for other vehicles.
  8.  
  9. Properly bleed the hydraulic brake system, including the EHCU/BPMV valve.
  10.  

FRONT WHEEL SPEED SENSORS



See Figures 2, 3, 4 and 5

  1. Raise and support the front of the vehicle safely using jackstands.
  2.  
  3. Remove the tire and wheel assembly.
  4.  
  5. Remove the brake caliper from the mounting bracket and support aside from the suspension using a coat hanger or wire. Make sure the brake line is not stretched, kinked or otherwise damaged. The line should NEVER support the weight of the caliper.
  6.  
  7. For 2wd vehicles, remove the hub and rotor assembly. For details, please refer to the brake disc procedure found earlier in this section.
  8.  



Click image to see an enlarged view

Fig. Fig. 2: Front wheel speed sensor/splash shield assembly mounting - 2wd vehicles



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Fig. Fig. 3: Front wheel speed sensor wire routing - 2wd vehicles

  1. For 4wd vehicles, remove the brake disc (please refer to the procedure earlier in this section), then remove the hub and bearing assembly. For details on hub and bearing removal, please refer to the steering knuckle procedure in Suspension & Steering of this repair guide.
  2.  
  3. Disengage the sensor wiring connector.
  4.  
  5. Disconnect the sensor wire from the clip(s) on the upper control arm. On most vehicles this will involve removing the retaining bolt/nut in order to free the clip, then separating the wire from the clip. 4wd vehicles tend to utilize more clips than the 2wd vehicles due to the difference in the front suspension.
  6.  
  7. Remove the splash shield retaining bolts, then remove the shield and sensor assembly.
  8.  

To install:
  1. Mount the sensor and splash shield assembly to the steering knuckle. Install the retaining bolts and tighten them to 11 ft. lbs. (15 Nm) for the Typhoon or to 19 ft. lbs. (26 Nm) for the outer bolts and 12 ft. lbs. (16 Nm) for the inner bolts on other vehicles.
  2.  



Click image to see an enlarged view

Fig. Fig. 4: Front wheel speed sensor/splash shield assembly mounting - 4wd vehicles



Click image to see an enlarged view

Fig. Fig. 5: Front wheel speed sensor wire routing - 4wd vehicles

  1. Connect the wiring to the clip(s) on the upper control arm. Check the wiring for correct routing. If removed, install and tighten the clip retaining bolt/nuts, refer to the illustrations for locations and torque specifications. The wiring on some vehicles/components may be marked at the appropriate clip mounting position, look for a paint stripe on the sensor wire.
  2.  
  3. Engage the wiring connector.
  4.  
  5. On 4wd vehicles, install the hub and bearing assembly.
  6.  
  7. Install the brake disc.
  8.  
  9. Remove the support, then reposition and secure brake caliper.
  10.  
  11. Install the tire and wheel assembly, then adjust the wheel bearings on 2wd vehicles.
  12.  
  13. Remove the jackstands and carefully lower the vehicle.
  14.  

REAR WHEEL SPEED SENSOR



The 1991-92 vehicles are the only vehicles covered by this information that utilize individual rear wheel speed sensors. The other ABS systems covered here utilize the Vehicle Speed Sensor (VSS) signal in order to determine rear wheel speed/lockup.

1991-92 Vehicles

See Figure 6

  1. Raise and support the rear of the vehicle safely.
  2.  
  3. Remove the tire and wheel assembly.
  4.  
  5. Matchmark and remove the brake drum.
  6.  
  7. Remove the primary brake shoe. For details, please refer to the brake shoe procedure located earlier in this section.
  8.  



Click image to see an enlarged view

Fig. Fig. 6: Rear wheel speed sensor - 1991-92 vehicles

  1. Disengage the sensor wiring at the connector.
  2.  
  3. Remove the sensor wire from the rear axle clips.
  4.  
  5. Remove the 2 bolts holding the sensor to the brake backing plate, then remove the sensor by carefully tracking the wire through the hole in the backing plate.
  6.  

To install:
  1. Route the wire through the backing plate and position the sensor.
  2.  
  3. Install the sensor bolts and tighten to 26 ft. lbs. (35 Nm).
  4.  
  5. Secure the sensor wire within the rear axle clips.
  6.  
  7. Engage the sensor wiring to the harness connector.
  8.  
  9. Install the primary brake shoe.
  10.  
  11. Align and install the brake drum.
  12.  
  13. Install the tire and wheel assembly, then remove the jackstands and carefully lower the vehicle.
  14.  

1993 Vehicles

The speed sensor is not serviceable and must be replaced if malfunctioning. The sensor is usually located in the left rear of the transmission case on 2wd vehicles and on the transfer case of 4wd vehicles. The speed sensor may be tested with an ohmmeter; the correct resistance is normally 900-2000 ohms. To remove the speed sensor:

  1. Raise and support the vehicle safely using jackstands.
  2.  
  3. Disengage the wiring connector from the speed sensor.
  4.  
  5. If used, remove the sensor retaining bolt.
  6.  
  7. Remove the speed sensor; have a container handy to catch transmission fluid when the sensor is removed.
  8.  

If equipped with the 4L60-E automatic transmission, use J-38417 or an equivalent speed sensor remover/installer tool whenever the sensor is serviced.

  1. Recover the O-ring used to seal the sensor; inspect it for damage or deterioration.
  2.  

To install:
  1. Coat the new O-ring with a thin film of transmission fluid.
  2.  
  3. Install the O-ring and speed sensor.
  4.  
  5. If a retaining bolt is used, tighten the bolt to 97 inch lbs. (11 Nm) in automatic transmissions or 107 inch lbs. (12 Nm) for manual transmissions.
  6.  
  7. Engage the wire harness to the sensor.
  8.  
  9. Remove the jackstands and carefully lower the vehicle.
  10.  

 
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