Pinpoint Test R : Front HALFSHAFT Speed Sensor

Refer to All Wheel Drive (AWD) for schematic and connector information.

Normal Operation and Fault Conditions

The front halfshaft speed sensor is a 2 wire variable reluctance sensor that measures the speed of the front differential ring gear. The AWD module provides a 9 volt reference signal on the FASS+ circuit (pin 7).

DTC Fault Trigger Conditions

DTC	Description	Fault Trigger Condition
AWD C0633: 14	Front Half Shaft Speed Sensor: Circuit Short To Ground Or Open	This DTC sets if the AWD module detects an open or short to ground in the front halfshaft speed sensor FASS+ circuit (pin 7).
AWD C0633: 17	Front Half Shaft Speed Sensor: Circuit Voltage Above Threshold	This DTC sets if the AWD module detects voltage on the FASS- circuit (pin 6). This could be caused by a short to power in the front halfshaft speed sensor circuits.
AWD C0633: 86	Front Half Shaft Speed Sensor: Signal Invalid	This DTC indicates the AWD module has determined a plausibility fault exists with the front halfshaft speed sensor. This may be caused by RFI induced in the speed sensor harness or a mechanical fault of the front axle disconnect actuator, intermediate shaft, or front differential.
AWD C0633: A1	Front Half Shaft Speed Sensor: System Voltage	This DTC sets if the AWD module detects either low or high voltage on the FASS+ circuit (pin 7).

Possible Sources

FASS+ circuit open, short to ground, or short to power
FASS- circuit short to power
Front halfshaft speed sensor
Vehicle harness

R1 REVIEW CONTINUOUS MEMORY DTC (DIAGNOSTIC TROUBLE CODE)
- Using a diagnostic scan tool, perform the continuous memory self-test.
Was DTC C0633: 86 the only DTC set?

Yes GO to R7

No GO to R2

R2 CHECK FOR VOLTAGE TO FRONT HALFSHAFT SPEED SENSOR

Disconnect the front halfshaft speed sensor C1990.

Inspect harness connector for damage. Verify terminals are not splayed, damaged, or pushed out of the connector.

Ignition ON.

Measure:

Positive Lead	Measurement / Action	Negative Lead
Refer to C1990-2	Courtesy of FORD MOTOR COMPANY	Ground

Is the voltage approximately 9 volts?

Yes

GO to R3

GO to R5

R3 CHECK SIGNAL RETURN CIRCUIT FOR AN OPEN CIRCUIT

Disconnect AWD module C3841.

Inspect harness connector for damage. Verify terminals are not splayed, damaged, or pushed out of the connector.

Measure:

Positive Lead	Measurement / Action	Negative Lead
Refer to C1990-1	Courtesy of FORD MOTOR COMPANY	Refer to C3841-6

Is the resistance less than 3 ohms?

Yes

GO to R4

No	REPAIR the open circuit.

R4 CHECK SIGNAL RETURN CIRCUIT FOR A SHORT TO VOLTAGE

Ignition ON.

Measure:

Positive Lead	Measurement / Action	Negative Lead
Refer to C1990-1	Courtesy of FORD MOTOR COMPANY	Ground

Is any voltage detected?

Yes	REPAIR the short to voltage.

No	INSTALL a new front halfshaft speed sensor. REFER to: Front Halfshaft Speed Sensor .

R5 CHECK FASS+ CIRCUIT FOR AN OPEN CIRCUIT

Disconnect the AWD module connector C3841.

Measure:

Positive Lead	Measurement / Action	Negative Lead
Refer to C1990-2	Courtesy of FORD MOTOR COMPANY	Refer to C3841-7

Is the resistance less than 3 ohms?

Yes

GO to R6

No	REPAIR the open circuit.

R6 CHECK FASS+ CIRCUIT FOR A SHORT TO GROUND

Ignition OFF.

Measure:

Positive Lead	Measurement / Action	Negative Lead
Refer to C1990-2	Courtesy of FORD MOTOR COMPANY	Ground

Is the resistance greater than 10, 000 ohms?

Yes	INSTALL a new AWD module. REFER to: All-Wheel Drive (AWD) Module .

No	REPAIR the short to ground.

R7 INSPECT FRONT HALFSHAFT SPEED SENSOR FOR DAMAGE
- Ignition OFF.
- With the transmission in NEUTRAL, position the vehicle on a hoist. REFER to: Jacking and Lifting .
- Disconnect the front halfshaft speed sensor electrical connector C1990.
- Inspect the front halfshaft speed sensor and harness connector for abrasions, broken connector tabs or water intrusion.
Is the front halfshaft speed sensor and harness connector OK?

Yes GO to R8

No INSTALL a new front axle speed sensor. REFER to: Front Halfshaft Speed Sensor .

R8 INSPECT FRONT HALFSHAFT SPEED SENSOR MOUNTING
- Check and installed the halfshaft speed sensor seated properly.
Is the front halfshaft speed sensor properly torqued and secure in the housing?

Yes GO to R9

No INSTALL a new front axle speed sensor. REFER to: Front Halfshaft Speed Sensor .

R9 VERIFY ALL WIRING CONNECTIONS
- Ignition OFF.
- Disconnect AWD module C3841.
- Disconnect all in-line connectors between the AWD module and the front halfshaft speed sensor.
- Using a good light source, inspect all disconnected electrical connectors for the following:
  - corrosion - install new connector or terminal and clean the module pins.
  - damaged or bent pins - install new terminals or pins.
  - pushed-out pins - install new pins as necessary.
  - spread terminals - install new terminals as necessary.
Are the connectors free of corrosion, damaged pins, bent pins, pushed-out pins and spread terminals?

Yes GO to R10

No REPAIR the connector or terminals. Refer to OEM GROUND DISTRIBUTION for schematic and connector information.

R10 CHECK FOR CORRECT AWD (ALL-WHEEL DRIVE) MODULE OPERATION

Connect all AWD module system electrical connectors.

Make sure all connectors seat and latch correctly.

Operate the system and determine if the concern is still present.

Yes	CHECK OASIS for any applicable TSBs. If a TSB exists for this concern, DISCONTINUE this test and FOLLOW the TSB instructions. If no TSBs address this concern, INSTALL a new AWD module, REFER to: All-Wheel Drive (AWD) Module . .

No	The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. ADDRESS the root cause of any connector or pin issues.