Hummer H3. Manual - part 632

Left Rear Wheel Speed Sensor Circuit

DTC C0050

Right Rear Wheel Speed Sensor Circuit

Diagnostic Fault Information

DTC C0035-C0050

Circuit/System Description

The wheel speed sensor receives a 12-volt power supply voltage from the electronic brake
control module (EBCM) and provides an output signal to the EBCM. As the wheel spins, the
wheel speed sensor sends the EBCM a DC square wave signal. The EBCM uses the frequency of
the square wave signal to calculate the wheel speed.

Conditions for Running the DTC

C0035-C0050

The ignition is ON.

Ignition voltage is greater than 9 volts.

IMPORTANT: Always perform the Diagnostic System Check - Vehicle prior to

using this diagnostic procedure.

Circuit

Short to

Ground

Open or

High

Resistance

Short to
Voltage

Signal

Performance

Left Front Sensor Signal

C0035

Left Front Sensor Low
Reference

C0035

Right Front Sensor Signal

C0040

Right Front Sensor Low
Reference

C0040

Left Rear Sensor Signal

C0045

Left Rear Sensor Low Reference

C0045

Right Rear Sensor Signal

C0050

Right Rear Sensor Low
Reference

C0050

2007 Hummer H3

2007 BRAKES Antilock Brake System - H3

Vehicle speed is greater than 10 km/h (6 mph) is required to detect rolling wheel speed
failures.

Conditions for Setting the DTC

C0035-C0050

An erratic signal output of the wheel speed sensor is detected.

A short to voltage, open or ground is detected on the wheel speed sensor signal circuit.

A open or short to ground in the wheel speed sensor circuit supply voltage.

Wheel speed sensor power supply is less than 7.6 volts.

A missing wheel speed sensor signal

Action Taken When the DTC Sets

The EBCM disables the Antilock Brake System (ABS)/Traction Control System
(TCS)/Vehicle Stability Enhancement System (VSES) for the duration of the ignition cycle.

ABS indicator turns ON.

Driver information center (DIC) displays the ABS FAULT message.

Stability Caution indicator turns on.

DIC displays the SERVICE STAB SYS message.

DIC displays the TRACTION FAILED message.

If both rear wheel speed DTCs are set, the dynamic rear proportioning (DRP) is disabled
and the Brake Warning indicator turns ON.

Conditions for Clearing the MIL/DTC

The condition for setting the DTC is no longer present and the DTC is cleared with a scan
tool.

The EBCM automatically clears the history DTC when a current DTC is not detected in 100
consecutive drive cycles.

An ECE 13 response may occur. If an ECE 13 response is present the vehicle must be
operated at a speed greater than 15 km/h (9 mph) to turn off the ABS warning lamp.

Diagnostic Aids

If 2 or more wheel speed sensors are inoperative diagnose each wheel speed sensor individually.

If the customer comments that the ABS indicator is ON only during moist environmental

2007 Hummer H3

2007 BRAKES Antilock Brake System - H3

conditions: rain, snow, vehicle wash, etc., inspect the wheel speed sensor wiring for signs of
water intrusion. If the DTC is not current, clear all DTCs and simulate the effects of water
intrusion by using the following procedure:

1. Spray the suspected area with a 5 percent saltwater solution. To create a 5 percent saltwater

solution, add 2 teaspoons of salt to 8 fl. oz. of water (10 g of salt to 200 ml of water).

2. Test drive the vehicle over various road surfaces, bumps, turns, etc., above 40 km/h (25

mph) for at least 30 seconds.

3. If the DTC returns, replace the suspected wheel speed sensor or repair the wheel speed

sensor wiring.

4. Rinse the area thoroughly when completed.

Reference Information

Schematic Reference

Antilock Brake System Schematics

Connector End View Reference

Antilock Brake System Connector End Views

Electrical Information Reference

Circuit Testing

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Connector Repairs

Scan Tool Reference

Scan Tool Data List

Circuit/System Verification

With scan tool installed drive the vehicle in a straight line at a speed greater than 10 km/h (6
mph), all wheel speed sensors should read the same speed.

Circuit/System Testing

Note: It is recommend that Component Testing is performed before Circuit Testing when
diagnosing wheel speed sensors.

2007 Hummer H3

2007 BRAKES Antilock Brake System - H3

Note: Performing Circuit Testing with EBCM connector disconnected and key on will cause U
codes to set. Clear DTCs after performing the test.

1. With the ignition OFF, Disconnect the wheel speed sensor connector. Ignition ON, Measure

for voltage above 7.5 V on the wheel speed sensor signal circuit.

If voltage is below 7.5 check for a short to ground, open or replace EBCM.

2. Ignition OFF, disconnect the EBCM connector. With the EBCM connector disconnected

and the ignition ON, measure for 0 volts between the wheel speed sensor signal circuit or
the wheel speed sensor low reference circuit and ground at the EBCM connector.

If over 0 volts, repair short to voltage in the wheel speed sensor signal circuit or the
wheel speed sensor supply voltage circuit.

3. With the ignition OFF and the wheel speed sensor harness disconnected, Measure for

infinite ohms of resistance between ground and the wheel speed sensor signal and the wheel
speed sensor low reference circuit from the EBCM connector.

If less than infinite ohms, repair short to ground in the sensor signal or the low
reference circuit.

4. Measure for infinite ohms of resistance between the wheel speed sensor signal circuit and

the wheel speed low reference circuit at the EBCM connector.

If less than infinite ohms, repair short between the wheel speed sensor signal circuit
and the wheel speed sensor low reference circuit.

If all circuits test normal replace the suspect wheel speed sensor.

Component Testing

1. ignition OFF, disconnect the wheel speed sensor connector. Measure for 12 volts on the

wheel speed sensor signal circuit.

If the If voltage is below 7.5 check for a short to ground, open or replace EBCM.

2. At the wheel speed sensor, connect a 3 Amp fused jumper wire between wheel speed sensor

low reference terminal and the low reference terminal of the wheel speed harness connector.
Set-up a DMM to measure current flow (mA/A). Connect the positive terminal of the DMM
to the wheel speed sensor signal terminal at the wheel speed sensor harness connector and
the negative lead to the wheel speed sensor signal terminal of the wheel speed sensor. Spin
the wheel very slowly. Measure for 4-8 mA on the low reading and 12-16 mA on the high
reading.

If the low amperage output of the wheel speed sensor signal circuit is below 4 mA or
above 8 mA replace the wheel speed sensor.

If the high amperage output of the wheel speed sensor signal circuit is below 12 mA or
above 16 mA replace the wheel speed sensor.

2007 Hummer H3

2007 BRAKES Antilock Brake System - H3

Content .. 630 631 632 633 ..