Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)

Or, hide this message: temporarily or permanently

Hardware Limited Operation Strategy

HLOS - HARDWARE LIMITED OPERATION STRATEGY
HLOS is a PCM function. HLOS provides minimal engine operation should the PCM stop functioning correctly. All modes of self-test are not functional and electronic hardware is in control of system.

HLOS allowable output functions:
- Spark output controlled directly by PIP signal.
- Fixed fuel pulse width synchronized with PIP signal.
- Fuel pump energized.
- Idle speed control output signal functional.

HLOS disabled outputs to default state:
- EGR solenoids
- No converter lock-up.