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)
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ISO Keyword Protocol 2000 Serial Data
Regulations require that all automobile manufacturers establish a common communications system. The Catera uses ISO (International Organization for Standardization) Keyword Protocol 2000 serial data. This system utilizes a single wire bi-directional data line between the ECM, the Traction Control Module
(TCM) and the scan tool. With this type of communication, a voltage level of less than 20 percent of B+ on the data line is considered a logic 0. A voltage level that is greater than 80 percent of B+ is considered a logic 1. The message structure is a request and response arrangement that has some similarities to the UART system.