LIGHT BRAKE DRAG RESULTING IN BRAKE PEDAL PULSATION. Saturn Saturn 1993

For 1990-2009 cars

# LIGHT BRAKE DRAG RESULTING IN BRAKE PEDAL PULSATION

#### SUBJECT: Slight Brake Drag Resulting in Brake Pedal Pulsation, Vehicle Vibration and/or Roughness, Slowing of Vehicle and/or Reduced Fuel Economy, Caused by a Misadjusted Stop Lamp (Brake Light/Cruise Control) Switch (Adjust Switch)

#### MODELS AFFECTED: 1991, 1992 and 1993 Saturns

CONDITION: Some customers may comment of:

o Noticeable slowing of vehicle and/or reduced fuel economy o Brake pulsation, noise, vibration, roughness or noise o Vehicle vibration, roughness or noise o Noticeable brake odor when stopped o Increased brake pedal travel during apply o Increased brake pedal effort during apply

These conditions may be caused by a lack of full brake return and slight brake drag.

CAUSE: The stop lamp switch on some vehicles may be misadjusted preventing full retun of the brake pedal arm when the brake pedal is released, resulting in a partial apply of the brake system and slight brake drag.

CORRECTIVE ACTION: A new procedure and gage have been developed to provide a more positive stop lamp switch adjustment. If a misadjusted stop lamp switch is discovered, the switch should be adjusted and the brake system inspected, and corrected if necessary, according to the procedures in this bulletin.

#### PROCEDURES

I. STOP LAMP SWITCH ADJUSTMENT CHECK

(See figure 1 for step 1)

1. Install stop lamp switch adjustment gage (SA 9303BR) between the switch and the switch actuator pad on the brake pedal arm being sure that the plunger protrudes through the slot in the gage.

(See figure 2 & 3 for steps 2 - 4)

2. With the pedal released and the adjustment gage in position, tap the gage side - to - side: a. If the gage swings freely side - to - side, proceed to Step 3. b. If the gage sticks or does not swing freely, adjust the switch using the following "Stop Lamp Switch Adjustment" procedure.

3. With the adjustment gage in position, pull up on the brake pedal with very light force (approximately 2 lbs.) and tap the gage side - to - side: a. If the gage swings freely, adjust the switch using the following "Stop Lamp Switch Adjustment" procedure. b. If the gage sticks and/or does not swing freely, the switch is properly adjusted.

4. If the stop lamp switch adjustment is correct and the vehicle exhibits any of the conditions described in this bulletin, refer to the "Brake Diagnostic" charts in this bulletin for other possible causes.

II. STOP LAMP SWITCH ADJUSTMENT (See figure 4 for steps 1 - 3)

1. Loosen the stop lamp switch mounting nut sufficiently to allow the switch

2. Install stop lamp switch adjustment gage (SA 9303BR) between the switch and the switch actuator pad on the brake pedal arm being sure that the plunger protrudes through the slot in the gage. 3. While pulling up with moderate force on the brake pedal assembly, push the switch forward against the gage.

#### IMPORTANT: Hold the switch perpendicular to the actuator pad on the brake pedal arm to prevent the switch from rotating out of alignment when tightening the switch mounting nut.

(See figure 5 for steps 4 - 6)

4. Tighten the switch mounting nut.

Torque: 10 N.m (89 in-lbs.)

5. Release the brake pedal assembly. 6. With the brake pedal released and the adjustment gage still in position, tap the gage side-to-side: a. If the gage swings freely side - to - side, proceed to Step 7. b. If the gage sticks or does not swing freely, repeat Steps 1 through 6.

(See figure 6 for steps 7 - 8)

7. With the adjustment gage in position, pull up on the brake pedal with very light force (approximately 2 lbs.) and tap the gage side-to-side: a. If the gage swings freely, repeat Steps 1 through 7. b. If the gage sticks and/or does not swing freely, the switch is properly adjusted.

8. Inspect the brake system using the "Brake System Inspection Procedure" in this bulletin and perform necessary repairs using the repair procedures in the "1991-1993 Brakes Service Manual."

III. BRAKE SYSTEM INSPECTION (See figure 7 for steps 1 - 4)

#### Front and Rear Disc

1. Remove the front and rear wheels using the "Wheel Removal" procedures in the "1991-1993 Chassis Service Manual." 2. Inspect the rotors for signs of increased heat and wear:

The braking surface of a rotor develops a "glaze" during normal use. This glaze is expected and desired. It is caused by the combination of compression and heat between the brake shoes and the rotor. This glaze does not indicate increased heat, is a normal condition, and improves brake performance and durability.

The braking surface of a rotor which has been only slightly overheated may appear normal. The brake surface of a rotor which has been overheated will appear very corroded The surface may also be blistered or flaking and the rotor must be replaced.

3. If the vehicle exhibited brake pedal pulsation, vibration and/or roughness, measure rotor runout and thickness variation using the "Inspecting and Refinishing Brake Rotors" procedures in the "1991-1993 Brakes Service Manual." 4. Replace or refinish the rotors if necessary, using the "Inspecting and Refinishing Brake Rotors" procedures in the "1991-1993 Brakes Service Manual." (See figure 8 for steps 5 - 6b) 5. Remove front and rear brake pads using the "Front Pads" and "Rear Pads" removal procedures in the "1991-1993 Brakes Service Manual." 6. Inspect the brake pads. A brake pad which has been overheated may show any or all of the following characteristics: a. Paint discoloring, blistering or corrosion on the thin metal insulator, side of lining material and/or back of shoe. b. Viton (fibrous material between thin metal insulator and shoe on back of pad) extruding from slots in insulator and sides of shoe.

(See figure 9 for steps 6c - 7)

c. Metal insulator separating from the back of shoe.

7. Install new disc brake pads if any of the above conditions are present using the "Front Pads" and/or "Rear Pads" installation procedures in the "1991-1993 Brakes Service Manual."

(See figure 10 for step 1 - 2a)

#### Rear Drum

1. Remove the rear drums using the "Rear Drum Removal" procedure in the "1991-1993 Brakes Service Manual." 2. Inspect the drums for signs of increased heat and wear. A drum which has been overheated may show any or all of the following characteristics: a. Paint blistering, discoloring or missing on the outer shell. Drums are painted black in color on the outer surfaces from a point outboard of the wheel mounting surface around on the outside of the drum shell. Some amount of discoloration and/or corrosion is normal and increases with age and exposure. Increased corrosion, discoloration and/or paint loss may indicate increased heat.

(See figure 11 for steps 2b - 5)

b. Blueing of the drum material. The blueing will be most noticeable on the inside corner between the braking surface and the drum mounting web. In almost all cases, blueing of the drum material indicates increased heat.

#### IMPORTANT: Natural sunlight or a bright shop light will help detect blueing. Blueing frequently can not be seen under normal lighting, unless it is severe.

3. If the vehicle exhibited brake pedal pulsation, vibration and/or roughness, or drum has been overheated, measure drum runout using a dial indicator with the drum mounted on a brake lathe. 4. If any of the above conditions are present, replace or refinish the drums using the "Inspecting and Refinishing Brake Drums" procedures in the "1991-1993 Brakes Service Manual." 5. Inspect and replace all other rear drum brake components as necessary using the "Rear Drum Brakes Disassembly and Assembly" procedures in the "1991-1993 Brakes Service Manual."

#### PERFORMANCE

The diagnostic charts included in this bulletin are taken from the complete charts found in the "1991-1993 Brakes Service Manual" and only contain causes and corrections that pertain to the conditions described in this bulletin.

Complaint/Condition: Brakes Drag --------------------

Possible Cause(s) Correction(s) ----------------- ------------- Incorrect stop lamp switch Adjust stop lamp switch. adjustment.

Caliper pistons stuck. Overhaul caliper and replace piston. Corroded caliper bolts. Caliper will not retract. Replace bolts and bolt boots. Compensating port or bypass hole in master Clean master cylinder cylinder clogged. and rebuild.

Worn or damaged drum Replace drum brake brake return springs. springs.

Contaminated or improper Flush brake system and brake fluid, rubber seals replace all rubber parts are swollen. including hoses.

Parking brake not releasing. Check parking brake adjustment, cables and lever. Customer "riding the brake Advise customer. pedal.

Park brake level not fully Advise customer. released.

Park brake lever in released Check parking brake adjustment, cables position, but rear shoes or and lever. pads not released.

Self-adjusters over adjusting Overhaul or replace adjusters. for lining wear.

Improper vacuum booster push Replace booster and push rod. rod length.

Complaint/Condition: Slow Response/Increased Stopping Distance --------------------

Possible Cause(s) Correction(s) ----------------- ------------- Improper rotor surface finish. Refinish or replace rotor.

Linings not adjusting properly, Overhaul drum brake or caliper. damaged self- adjusters or worn piston seal.

Caliper pistons sticking. Overhaul caliper and replace piston.

Worn or glazed linings. Replace linings.

Proportioning valve not functioning Replace master cylinder. properly.

Complaint/Condition: Odor --------------------

Possible Cause(s) Correction(s) ----------------- ------------- Linings overheated. (Refer to symptoms under Brakes Drag.)

Lining(s) contaminated with foreign Replace Lining(s). substances.

Complaint/Condition: Poor Fuel Economy --------------------

Possible Cause(s) Correction(s) ----------------- ------------- Linings overheated. (Refer to symptoms under Brakes Drag.)

Complaint/Condition: Increased Pedal Travel --------------------

Possible Cause(s) Correction(s) ----------------- ------------- Air in brake system. Bleed brake system.

Front or rear brakes not adjusting to Check adjuster mechanism and lining wear. replace or repair as needed.

Increased brake system heat. Refer to symptoms under Brakes Drag. Increased wheel bearing end play. Replace wheel bearing.

Increased wheel hub runout. Replace wheel hub.

Caliper not sliding freely. Repair or replace caliper/mounting pins. Leaking wheel cylinder or caliper Replace wheel cylinder or overhaul piston seal. caliper.

Leak at brake line or hose Tighten connection. Replace line or connections. hose.

Faulty booster check valve. Replace booster check valve.

Internal master cylinder seal leak. Overhaul or replace master cylinder.

Uneven lining wear or damaged Replace linings. lining.

Rotor or drum out of specifications Replace rotor, or drum. (i.e. rotor thickness variation, lateral runout, etc.).

Improper vacuum booster to master Replace booster and pushrod. cylinder pushrod length.

Complaint/Condition: Pedal Pulses --------------------

Possible Cause(s) Correction(s) ----------------- ------------- Increased brake system heat. Refer to symptoms under Brakes Drag. Rotor or drum out of specifications Replace or refinish rotor or drum. (i.e. lateral runout, parallelism, out of round, etc.).

Worn out linings or linings wearing Replace linings. unevenly.

Wheel bearings worn. Replace wheel bearing.

Damaged suspension, knuckle or axle. Replace defective parts.

Complaint/Condition: Increased Pedal Effort --------------------

Possible Cause(s) Correction(s) ----------------- ------------- Low vacuum to booster. Check and repair engine vacuum, booster check valve or hose. Leaking or damaged vacuum booster Replace booster. (i.e. cut diaphragm, cracked power piston, restricted air passages).

Worn out brake linings (glazed). Replace linings.

Damage to braking surface of rotor or Replace rotor or drum. drum.

Crimped brake line or collapsed Replace line or hose. brake hose.

Complaint/Condition: Squeal/Scrape While Not Braking --------------------

Possible Cause(s) Correction(s) ----------------- ------------- Worn linings, wear sensor scraping on Replace linings. rotor (normal).

Loose drum brake component Check drum brake and repair. (spring, lever, adjuster, etc.).

Loose front suspension attachments. Tighten attachments or replace.

Caliper interference with rotor. Check clearance and repair.

Bent or cracked suspension parts. Replace components.

Drum or rotor contacting backing Check clearance and repair. plate or dust shield.

Complaint/Condition: Squeal/Scrape While Braking --------------------

Possible Cause(s) Correction(s) ----------------- ------------- Worn Linings, wear sensor scraping on Replace linings. rotor (normal).

Linings worn out, shoe contacting Replace linings. drum or rotor.

Lack of lubrication on backing plate Lubricate. or on adjuster screw.

Lack of lubrication on caliper sliding Lubricate. surfaces.

Lack of lubrication on brake pedal Lubricate. attachments.

Damage to insulator between disc Replace shoe and linings as needed. brake shoe and caliper piston.

Hot spots or worn surface on drum or Replace rotor or drum. rotor.

Weak hold down springs or worn Replace drum brake springs. drum brake components.

Complaint/Condition: Chatters/Rattles --------------------

Possible Cause(s) Correction(s) ----------------- ------------- Hot spots or worn surface on drum or Replace drum or rotor. rotor.

Rotor or drum out of specifications Replace or refinish rotor or drum. (i.e. lateral runout, parallelism, out of round, etc.).

Lining contaminated with foreign Replace linings. substances.

Linings wearing unevenly. Replace linings.

Bent or loose brake shoes. Replace shoes and linings.

Weak or broken retractor springs. Replace drum brake springs.

Loose brake cable, brake line, or ABS Check cable or line connection and wiring. tighten or replace as needed.

Complaint/Condition: Groans (at/near stop) --------------------

Possible Cause(s) Correction(s) ----------------- ------------- Linings worn out. Replace linings.

Incorrect or damaged lining material. Replace linings.

Hot spots or worn surface on drum or Replace drum or rotor. rotor.

Cracked or bent knuckle or Replace suspension component. suspension parts.

Loose suspension. Tighten suspension or replace.

#### SPECIFICATIONS

mm in.

BRAKE PEDAL TRAVEL 57.0 2.25 Brake pedal travel maximum with 445 N (100 lbs.) force applied to pedal with ignition Off and vacuum assist depleted.

BRAKE DRUMS Runout 0.15 0.006 Inside Diameter 200.0 7.87 Maximum Refinish Diameter 200.6 7.90 Discard Diameter 201.4 7.93

BRAKE ROTORS Lateral Runout 0.060 0.0024 Thickness Variation 0.013 0.0005

FRONT Diameter 250.5 9.86 New Thickness (Nominal) 18.0 0.710 Minimum Thickness After Refinish 16.1 0.633 Discard Thickness 15.8 0.625

REAR Diameter 245.0 9.65 New Thickness (Nominal) 11.0 0.44 Minimum Thickness After Refinish 9.3 0.37 Discard Thickness * 9.0 0.35

* Brake drums and rotors have a discard diameter or thickness dimension cast into them. This is a wear dimension and not a refinish dimension. Any drum or rotor which does not meet the specification should be discarded.

BRAKE LININGS Front Disc Pads New Thickness 11.0 0.43 Discard Thickness 2.0 0.08

Rear Disc Pads New Thickness 9.0 0.35 Discard Thickness 2.0 0.08

Rear Drum Shoes New Thickness 4.0 0.16 Discard Thickness 1.0 0.04

HUB AND BEARING ASSEMBLES Front End Play 0.020 0.001 Lateral Runout 0.040 0.0016

Rear End Play 0.130 0.005 Lateral Runout 0.050 0.002 Radial Runout 0.130 0.005

MASTER CYLINDER BORE DIAMETER 22.2 0.87

CALIPER BORE DIAMETER Front 51.0 2.01 Rear 31.8 1.25

WHEEL CYLINDER BORE DIAMETER 19.0 0.75

MINIMUM VACUUM AT POWER BOOSTER 15 in. Hg.

BRAKE SYSTEM FLUID CAPACITY 0.5 liters 17.0 oz.

CLAIM INFORMATION: To receive credit for this repair, submit a claim through the Saturn Dealer System as follows:

Labor Case Operation Type Description Code Time ---- ----------- ---------- ----- VW Stop Lamp Switch Adjustment T9641 0.2 hrs Check Only

VW Stop Lamp Switch Adjustment - T9642 Check & Adjust and Perform W/0 ABS 1.2 hrs Brake System Inspection With ABS 1.6 hrs (Per Bulletin Procedure)

Add if required: A. To Reface Rotor (One) 0.6 hrs Including: R&R of Rotor B. To Reface Each Additional Rotor 0.5 hrs Including: R&R of Rotor(s) C. To Replace Rotor (Each) 0.2 hrs Front or Rear D. To Reface Rear Drum (One) 0.4 hrs E. To Reface Rear Drum (Both) 0.7 hrs

#### NOTE: For any other required repairs, refer to the appropriate Electronic Saturn Labor Time Guide for the correct operation number and time.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.