Test 3: Wheel Speed Sensor Signal Problem

NOTE: DTC 29 may set when vehicle is towed, raised or steering wheel is held at full lock continuously.

Ensure tires are proper size, tire pressure is correct and tires are not excessively worn. Repair or replace as needed.
Ensure wheel sensor bolts and tone wheel bolts are tight. Tighten as needed. See TORQUE SPECIFICATIONS . Go to next step.
Measure sensor to tone wheel air gap around entire wheel. Gap should be .035-.055" (.9-1.4 mm) on front wheels and .028-.047" (.7-1.2 mm) on rear wheels. If gap is too small, use Spacer (26755AA000) to increase gap to specification. If gap exceeds specification, remove spacer(s) and replace tone wheel or faulty wheel speed sensor. When gap is set, go to next step.

If an oscilloscope is not available, go to step 6). If an oscilloscope is available, raise and support vehicle with wheels off of ground. Turn ignition off. On Forester models, connect oscilloscope to appropriate connector terminals at bulkhead connector B100, located at top left corner of dash. See Figure . See CHECKING ABS SENSOR SIGNAL USING OSCILLOSCOPE (FORESTER) table. On Impreza models, connect oscilloscope to appropriate connector terminals at bulkhead connector B100, located at top left corner of dash, and 12-pin wiring harness connector F55, located behind instrument cluster. See Figure . See CHECKING ABS SENSOR SIGNAL USING OSCILLOSCOPE (IMPREZA) table. On Legacy models, connect oscilloscope to appropriate connector terminals at bulkhead connector B100, located at top left corner of dash, and 8-pin wiring harness connector F1, located at top left corner of dash. See Figure . See CHECKING ABS SENSOR SIGNAL USING OSCILLOSCOPE (LEGACY) table.

CHECKING ABS SENSOR SIGNAL USING OSCILLOSCOPE (FORESTER)

DTC

⁽¹⁾⁽²⁾ B100 Terminals No.

9 & 22

11 & 24

1 & 12

3 & 14

⁽¹⁾	See Figure .

⁽²⁾	Second terminal listed is to be connected to oscilloscope ground lead.

CHECKING ABS SENSOR SIGNAL USING OSCILLOSCOPE (IMPREZA)

DTC

⁽¹⁾⁽²⁾ Connector (Terminals No.)

B100 (5 & 14)

B100 (7 & 16)

F55 (6 & 7)

F55 (1 & 2)

⁽¹⁾	See Figure .

⁽²⁾	Second terminal listed is to be connected to oscilloscope ground lead.

CHECKING ABS SENSOR SIGNAL USING OSCILLOSCOPE (LEGACY)

DTC

⁽¹⁾⁽²⁾ Connector (Terminals No.)

B100 (12 & 13)

B100 (3 & 4)

F1 (5 & 4)

F1 (2 & 1)

⁽¹⁾	See Figure .

⁽²⁾	Second terminal listed is to be connected to oscilloscope ground lead.

NOTE: This test procedure when completed, may set DTC 29.

On all models, turn ignition on. Observe oscilloscope while rotating each wheel, depending on trouble code. Voltage reading on oscilloscope should be .12-1.00 volt (AC waveform). If voltage is not as specified or waveform is erratic, go to next step. If voltage and waveform is as specified, go to step 8).
Check sensor and tone wheel for damage or contamination. Clean, repair or replace as needed. Go to next step.
Check hub runout. If runout is less than .002" (.05 mm), go to next step. If runout is .002" (.05 mm) or more, replace hub.
Turn ignition off. Reconnect all connectors. Erase memory. Recheck for trouble codes. If same trouble code returns, replace ABSCM/HU. If other trouble codes exist, go to proper test procedure. If no trouble codes exist, problem was a temporary poor contact. Check harness and connectors.