Antilock Braking System (ABS)

DTC 34: Left Rear Wheel Speed Sensor Circuit Open Or Shorted To Ground/Battery (Part 1 Of 3):

DTC 34: Left Rear Wheel Speed Sensor Circuit Open Or Shorted To Ground/Battery (Part 2 Of 3):

DTC 34: Left Rear Wheel Speed Sensor Circuit Open Or Shorted To Ground/Battery (Part 3 Of 3):

DTC 34 Left Rear Wheel Speed Sensor Circuit Open Or Shorted To Ground/Battery (For ABS With VES Only):

CIRCUIT DESCRIPTION
As a toothed ring passes by the wheel speed sensor, changes in the electromagnetic field cause the wheel speed sensor to produce a sinusoidal (AC) voltage signal whose frequency is proportional to wheel speed. The magnitude of this signal is directly related to wheel speed and the proximity of the wheel speed sensor to the toothed ring, often referred to as the air gap.

DTC WILL SET WHEN
DTC 34 can be set anytime after the Antilock Braking System (ABS) enable relay has been commanded "ON." The relay is commanded "ON" during the three second bulb check.

ACTION TAKEN
A malfunction DTC is stored, Antilock Braking System/Variable Effort Steering (ABS/VES) is disabled and the ABS warning lamp is turned "ON."

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. Checks wheel speed sensor circuitry for proper resistance values.
2. Checks for a short to ground in the wheel speed sensor circuitry.
3. Checks for a short to voltage in the wheel speed sensor circuitry.
4. Ensures malfunction was not due to physical damage of the circuitry.
5. Checks for a short to voltage in the wheel signal low circuit.
6. Checks for a short to voltage in the wheel signal high circuit.
7. Checks for high resistance in the wheel signal high circuit.
8. Checks for high resistance in the wheel signal low circuit.
9. Checks for proper resistance to the wheel speed sensor.
10. Checks for a short to ground in the wheel signal high circuit.
11. Checks for a short to ground in the wheel signal low circuit.
12. Checks for a short to ground in the rear ABS harness.
13. Checks for a short to ground in the wheel speed sensor.

DIAGNOSTIC AIDS
An "Intermittent" malfunction is most likely caused by a poor connection, rubbed through wire insulation, or a wire that is broken inside the insulation.

The frequency of the malfunction can be checked by using the enhanced diagnostic function of the Tech 1.

If the customer's comments reflect that the ABS amber warning lamp is "ON" only during moist environmental changes, (rain, snow, vehicle wash) all wheel speed sensor circuitry should be thoroughly inspected for signs of water intrusion. Use the following procedure. Spray down the suspected area with 5% salt water solution (two teaspoons of salt to 12 oz. of water). Drive vehicle above 24 km/h (15 mph) for at least 30 seconds. If DTC returns immediately, replace suspected harness.

Any circuitry, that is suspected as causing the intermittent complaint, should be thoroughly checked for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wiring connections or physical damage to the wiring harness.

Resistance of the wheel speed sensor will increase with an increase in sensor temperature.

When replacing a wheel speed sensor, inspect the sensor terminals and harness connector for corrosion and/or water intrusion. If evidence of corrosion or water intrusion exists, replace wheel speed sensor harness.

If wheel speed sensor harness shows evidence of water intrusion, inspect wheel speed sensor for water intrusion. If water intrusion is evident, replace wheel speed sensor.