Chrysler Caravan/Voyager/Town n Country 1984-1995

Diagnosis and Testing


See Figures 1, 2, 3, 4, 5, 6, 7 and 8

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Fig. Fig. 1: DRB-II Fault Messages-Bendix ABS System 10

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Fig. Fig. 2: ABS controller-60 pin connector-pin identification

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Fig. Fig. 3: System schematic: Normal driving brakes off-Bendix ABS System 10

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Fig. Fig. 4: System schematic: Normal driving brakes applied-Bendix ABS System 10

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Fig. Fig. 5: System schematic: ABS braking-hold pressure-Bendix ABS System 10

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Fig. Fig. 6: System schematic: ABS braking-Decay pressure-Bendix ABS System 10

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Fig. Fig. 7: System schematic: ABS braking-Build pressure-Bendix ABS System 10

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Fig. Fig. 8: ABS System wiring schematic-Bendix ABS System 10


This brake system uses hydraulic accumulators which, when fully charged, contain brake fluid at very high pressure. Before disconnecting any hydraulic lines, hoses or fittings be certain that the accumulator pressure is completely relieved. Failure to depressurize the accumulators may result in personal injury and/or vehicle damage.

Certain components within the ABS system are not intended to be serviced or repaired individually. Only those components with removal and installation procedures should be serviced.
The accumulator contains high pressure nitrogen gas to assist in pressurizing the system. The gas pressure is maintained even after fluid pressure in the system is reduced. Never puncture or attempt to disassemble this component.
Do not use rubber hoses or other parts not specifically specified for the ABS system. When using repair kits, replace all parts included in the kit. Partial or incorrect repair may lead to functional problems and require the replacement of components.
Lubricate rubber parts with clean, fresh brake fluid to ease assembly. Do not use lubricated shop air to clean parts; damage to rubber components may result.
Use only DOT 3 brake fluid from an unopened container.
If any hydraulic component or line is removed or replaced, it may be necessary to bleed the entire system.
A clean repair area is essential. Always clean the reservoir and cap thoroughly before removing the cap. The slightest amount of dirt in the fluid may plug an orifice and impair the system function. Perform repairs after components have been thoroughly cleaned; use only denatured alcohol to clean components. Do not allow ABS components to come into contact with any substance containing mineral oil; this includes used shop rags.
The Controller Anti-lock Brakes (CAB) is a microprocessor similar to other computer units in the vehicle. Ensure that the ignition switch is OFF before removing or installing controller harnesses. Avoid static electricity discharge at or near the controller.

  1. Turn the ignition switch OFF and leave it OFF during repairs unless specifically directed otherwise. Alternately, the negative battery cable may be disconnected; it must remain disengaged throughout the repairs.
  3. Firmly apply and release the brake pedal a minimum of 40 times, using at least 50 lbs. (222 N) of pedal force.
  5. The pedal feel will become noticeably harder when the accumulator is completely discharged. Once this is felt, apply the brake pedal forcefully a few additional times. This will remove all hydraulic pressure from the system.
  7. Do not turn the ignition switch ON or reconnect the battery cable after depressurizing the system unless service procedures specifically require it or all service operations have been performed.

After the reserve pressure is depleted, the fluid level in the reservoir may rise above the MAX fill mark. This is normal; the reservoir will not overflow unless the system was overfilled to begin with.

  1. Always wear safety goggles when disconnecting lines and fittings.


Diagnosis of the ABS system consists of 3 general steps, performed in order. The visual or preliminary inspection is always required before any other steps are taken. A functional test drive is performed to confirm the existence of a problem. The functional test will indicate the need for specific diagnostic tests to be performed.

Some diagnostic tests will require the ignition being left ON for a period of time. This could lead to lowered battery voltage and erroneous voltage readings within the system. Unless the battery is known to be in sound condition, connect a slow-charger to the battery when performing extended testing.

Visual Inspection

Before diagnosing an apparent ABS problem, make absolutely certain that the normal braking system is in correct working order. Many common brake problems (dragging lining, seepage, etc.) will affect the ABS system. A visual check of specific system components may reveal problems creating an apparent ABS malfunction. Performing this inspection may reveal a simple failure, thus eliminating extended diagnostic time.

  1. Depressurize the system.
  3. Inspect the brake fluid level in the reservoir.
  5. Inspect brake lines, hoses, master cylinder assembly, brake calipers and cylinders for leakage.
  7. Visually check brake lines and hoses for excessive wear, heat damage, punctures, contact with other parts, missing clips or holders, blockage or crimping.
  9. Check the calipers and wheel cylinders for rust or corrosion. Check for proper sliding action if applicable.
  11. Check the caliper and wheel cylinder pistons for freedom of motion during application and release.
  13. Inspect the wheel speed sensors for proper mounting and connections.
  15. Inspect the tone wheels for broken teeth or poor mounting.
  17. Inspect the wheels and tires on the vehicle. They must be of the same size and type to generate accurate speed signals. Check also for approximately equal tire pressures.
  19. Confirm the fault occurrence with the operator. Certain driver induced faults, such as not releasing the parking brake fully, will set a fault code and trigger the dash warning light(s). Excessive wheel spin on low-traction surfaces, high speed acceleration or riding the brake pedal may also set fault codes and trigger a warning lamp. These induced faults are not system failures but examples of vehicle performance outside the parameters of the CAB.
  21. The most common cause of intermittent faults is not a failed sensor but a loose, corroded or dirty connector. Incorrect installation of the wheel speed sensor will cause a loss of wheel speed signal. Check harness and component connectors carefully.

Functional Check

If the visual inspections do not lead to resolution of the problem, the test drive, or functional check must be preformed. Keep in mind that the vehicle being driven, may have a problem affecting its braking ability; check the brakes at a very low speed in a safe location before beginning an extended drive. A recommended method of testing and test driving for an ABS fault is:

  1. Turn the ignition ON without starting the engine. Wait until both the BRAKE and ANTI-LOCK warning lights turn off. This will allow the pump to charge the system; if either or both warning lamps do not go off, proceed to Step 3.
  3. Turn the ignition switch OFF for 15 seconds.
  5. Start the engine. Wait for displays to achieve normal operation.
  7. Place the shift lever in P . Using a full pedal stroke, slowly depress the brake pedal and release it.
  9. Drive the vehicle carefully for a short distance. Achieve a speed of at least 20 mph (32 km/h); bring the vehicle to a full stop then accelerate to at least 20 mph (32 km/h).
  11. If either the BRAKE or ANTI-LOCK warning lamps comes on, a fault has been detected by the CAB and, in most cases, a fault code has been entered into the memory.

Intermittent Faults

Most intermittent faults are caused by loose or faulty connections or wiring. Always check suspect circuits for poor mating of connector halves, improperly formed or damaged terminals. Any sign of corrosion or entry of foreign matter within a connector shell is cause for suspicion.

Most of the system faults will cause the ABS system to be disabled for the entire ignition on-off cycle. These are termed latching faults; in this case the warning lamp(s) will remain illuminated, even if the problem self-corrects during operation. There are some conditions which will allow the ABS function to be restored during a driving cycle; if one of these non-latching conditions exists and then ceases to exist, the warning lamp(s) will go off. When diagnosing a complaint of intermittent warning lamp illumination, investigate the following causes:

Low system voltage. Once the CAB detects the correct voltage, the ABS function will be restored.
Low brake fluid level. Once the fluid level sensor reads a normal level, system function is restored.
Low accumulator pressure. May occur after long or hard stopping or as a result of riding the brake pedal. Once correct minimum pressure is achieved, the system is restored.
Any interruption of power to either the CAB or the hydraulic assembly. Check the main power circuits, relays, fusible links and all related wiring.

Diagnostic Mode

Connect the DRB II or equivalent tester, according to instructions furnished with the tool. The system will enter diagnostic mode and prompt the operator through the assorted system checks and tests.