System Diagnosis

System diagnosis can be accomplished using an appropriate scan tester or a voltmeter. See RETRIEVING CODES. The TCL module monitors several different inputs. If an abnormal input signal occurs, a trouble code is stored in TCL module memory and assigned a trouble code number. Each circuit has its own trouble code number and message. A specific trouble code indicates a particular system failure, but does not indicate that cause of failure is necessarily within system.

A trouble code does not condemn any specific component; it simply points out a probable malfunctioning area. If a trouble code is set, the TCL module will turn on TCL warning light.