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

Test E

PINPOINT TEST E: NO POWERTRAIN CONTROL MODULE (PCM) STANDARD CORPORATE PROTOCOL (SCP) NETWORK COMMUNICATION


Test E1-E3:






Normal Operation
The PCM communicates with the modules through the standard corporate protocol (SCP) communications network. Circuits 4-RE8 (GY) and 5-RE8 (BU) receive and transmit data from the PCM to the modules. Degraded SCP performance occurs if one bus line is open, shorted to ground or voltage, or if one but not all termination resistors are lost.

Possible Causes
- circuits 4-RE8 (GY) and/or 5-RE8 (BU) shorted to ground or open
- PCM C175a
- DLC C251
- PCM