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

Coolant Temperature Override Switch

Fig. 23 EGR CTO switches:

This switch, Fig. 23, is located on the left side of the engine block on 6-258 engines.
When coolant temperature is below the specified rating of the CTO switch, there is no vacuum signal to the EGR system. The switch opening temperature is 85° F for switch with white body, 115° F for switch with black body or paint dab and 160° F for switch with yellow body or paint dab.