Troubleshooting table
- Make
- Alfa Romeo
- Model
- 155 Factory Service Manual
- Year
- 1992–1998
- Section
- Troubleshooting using the self-diagnosis function › Troubleshooting table
The self-diagnosis function with which this system is equipped makes a rapid identification of the faulty components possible by following the indications given by a FLASHING CODE which is actuated in the following way:
- connect the line of pin A, connector T1 to ground (LTB- WHT)
- provide power to the ABS control unit N51 (key-operated supply)
- read the sequence of impulses which appear on the "ABS malfunction" warning light located on the instrument panel C10:
- code "12" will appear three times to indicate correct operation: If this does not occur, carry out test A
• the codes of the stored errors will appear (each repeated three times): carry out the test indicated in the following table
• code "12" will appear another three times to indicate the end of the sequence
NOTE: To reset the stored codes, disconnect the line of pin A, connector T1 and actuate the ignition switch 20 times (or use the ALFA ROMEO Tester)
TROUBLESHOOTING TABLE
| CODE | MALFUNCTION | SEE TEST |
|---|---|---|
| 12 | Beginning and end of diagnosis Control unit anomaly and self-diagnosis | A |
| No code | 16 Faulty front left solenoid valve (VL) | Check solenoid valve impedance (1.5+2.5 Ω) and the connections between control unit and solenoid valve; If necessary replace the solenoid valve |
| 17 | Faulty front right solenoid valve (VR) | Check solenoid valve impedance (1.5+2.5 Ω) and the connections between control unit and solenoid valve; If necessary replace the solenoid valve |
| 18 | Faulty rear (HA) solenoid valve | Check solenoid valve impedance (1.5+2.5 Ω) and the connections between control unit and solenoid valve; If necessary replace the solenoid valve |
| 19 | Faulty safety relay | B |
| 25 | Incorrect number of teeth on phonic wheel | Replace the affected phonic wheel (see "REPAIR MANUAL-MECHANICAL UNITS" - Group 22) |
| 35 | Faulty pump motor | C |
| 37 | Faulty brake switch (H3) | D |
| 39 | Faulty front left sensor (L29) | Check sensor impedance (approximately 1 KΩ); replace it if necessary. Carry out successive test E. |
| 41 | Front left sensor (L29) not connected | E |
| 42 | Faulty front right sensor (L28) | Check sensor impedance (approximately 1 KΩ); replace it if necessary. Carry out successive test F. |
| 43 | Front right sensor (L28) not connected | F |
| 44 | Faulty rear left sensor (L31) | Check sensor impedance (approximately 1 KΩ); replace it if necessary. Carry out successive test G. |
| 45 | Rear left sensor (L31) not connected | G |
| 46 | Faulty rear right sensor (L30) | Check sensor impedance (approximately 1 KΩ); replace it if necessary. Carry out successive test H. |
| 47 | Rear right sensor (L30) not connected | H |
| 48 | Insufficient voltage | I |
| 55 | Faulty electronic control unit | Replace the control unit, located in N51 |
AUTOMATIC CHECKING UPON IGNITION:
when the vehicle is started the "ABS malfunction" warning lamp located on the instrument panel will come on for approximately 2 secs., and will then go out indicating that the system is operating correctly.
If the lamp stays on, carry out diagnosis using the flashing code as shown above.
If the warning lamp does not come on, carry out test A.
Parts & tools for this job For 1992 Alfa Romeo 155
- TOOLOBD2 scannerSearch: OBD2 scanner
- TOOLDigital multimeterSearch: automotive digital multimeter
- TOOLBack-probe test leadsSearch: back probe test leads
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