B448 Low Refrigerant Pressure

BCM Code B448:

Low Refrigerant Switch Circuit:

CIRCUIT DESCRIPTION:
The BCM monitors certain system inputs for an indication of low refrigerant charge. The BCM monitors the normally closed A/C refrigerant switch at pin "3D2." The status of the A/C refrigerant switch is checked prior to compressor engagement. If the return voltage to the BCM indicates the switch is open, the compressor will not be allowed to engage and a Code B448 will be set in diagnostics. Additionally, the CCDIC will switch to ECON mode and the "LOW A/C REFRIGERANT, A/C COMPRESSOR OFF" message will be displayed.

TEST DESCRIPTION: Test numbers refer to circled numbers on the diagnostic chart.

1. Checks current state of A/C refrigerant switch.
2. Checks circuits to A/C refrigerant switch.
3. Checks refrigerant system pressure.
4. Checks for restriction in refrigerant system.
5. Checks for intermittent short/open.