Fault (Trouble) Codes 4/24221, 2422A, 24251 & 24291

1. Raise and support vehicle.
2. With ignition in Drive position, enter ISAT command code 259. The code displayed will be between 80002 and 80020 (0-20 km/h), depending on whether wheel is stationary or being rotated by hand.
3. With a.c. range selected on multimeter, signal can also be measured by connecting probes across pins 30 and 48. Voltage should be approximately 0.1-0.5V a.c. as wheel is rotated by hand.
4. With ignition in Off position and ECU connector disconnected, check sensor winding for continuity by measuring resistance across pins 30 and 48. Resistance should be approximately 1100 ohms.
5. Check leads between sensor and pins 30 and 48 on TC/ABS-system ECU for shorting. Check for poor contact in connectors. Resistance should be as follows:
a. Pin 30 and ground: infinity.
b. Pin 48 and ground: infinity.
6. When testing for short to +12V, voltage should be as follows:
a. Pin 30 and ground: 0V d.c. (indicates no short to 12V).
b. Pin 48 and ground: 0V d.c. (indicates no short to 12V).
7. Ensure left front wheel sensor is properly installed.
8. Ensure sensor wheel is not damaged and is properly installed. Check for play in wheel bearings.
9. Check clearance between sensor and sensor wheel.
10. Ensure ECU pins 1 and 19 are properly grounded.
11. If no fault has been found, test drive vehicle to see if fault code is regenerated. If so, try a known good ECU.