Scan Tool Does Not Communicate With Keyword Data Line

SCAN TOOL DOES NOT COMMUNICATE WITH KEYWORD DATA LINE

CIRCUIT DESCRIPTION
The Keyword protocol utilizes a single wire bi-directional data line between the modules and the scan tool. The message structure is a request and response arrangement. Keyword serial data is used for scan tool diagnostics only. The modules do not exchange data on this circuit. There are two independent Keyword serial data circuits connected to data link connector (DLC) terminals 7 and 12.

Keyword Serial Data to DLC pin 7
- Engine control module (ECM)
- Transmission control module (TCM), if equipped

Keyword Serial Data to DLC pin 12
Electronic brake control module (EBCM)

TEST

Steps 1 - 6:

Steps 7 - 9: