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

Overdrive Ratio

Overdrive Ratio Error Circuit:





The overdrive ratio is determined from input speed and engine speed.

When TCC is engaged in 4th gear, if there is more than a 200 rpm difference between engine speed and input speed for at least two seconds, code 68 will set.

While code 68 is set, the following fail-safe actions will be taken:
^ Inhibit 4th Gear
^ Inhibit TCC Operation
^ Use Default Value for Pressure (force motor duty cycle)
^ Assume Drive 4 Shift Pattern

The system will recover on the next ignition cycle.