B1540

Fig.24 Code B1540: Boost Pressure Control Valve, No Voltage Supply Open Circuit:

Fault symptom
ABS warning lamp on, no ABS function.

Condition
- If three or more valves lack voltage supply.
- If the internal voltage relay is out of order.
- The electronic control module lacks a +30 voltage supply (connector pins 17 and 18).

Diagnostic procedure
1 +30 voltage supply check
- Remove the electronic control module connector. Take a voltage measurement at the electronic control module sensor connector. Connect the voltmeter
- between pin 17 and B+ = <0.5 V
- between pin 18 and B+ = <0-5 V

Are the voltage ratings OK?
YES - Continue with point 2.
NO - Check and possibly rectify the wiring between pin 17 and 18 of the electronic control module and the MAXI 2 fuse. If the wiring is correct, continue fault diagnosis in "Power supply +30". Electrical Diagrams

2 Final inspection
- Erase the diagnostic trouble code.
- Carry out the driving cycle, drive the car with various load and engine speeds for 5 minutes.
- Read the diagnostic trouble code.

Is the diagnostic trouble code stored?
YES - Continue on "Test Procedure Prior To Replacing ECM"
NO - The diagnostic procedure performed is right or the fault is of intermittent character.