Diagnostic Trouble Code Output Format

The EEC system communicates service information by way of Diagnostic Trouble Codes (DTC). These DTCs are two digit numbers representing Diagnostic Test Mode (DTM) results.

Diagnostic Trouble Codes are transmitted on the Self Test Output (STO) line or the Data Link Connector (DTC). Diagnostic Trouble Codes are in the form of timed pulses, read by the technician on a scan tool, analog voltmeter, or Malfunction Indicator Lamp (MIL).

Code Cycle Break:

CODE CYCLE BREAK
The time between code cycles is 4.0 seconds (time the light is off).

First Digit Of Service Code (Tens Position) During One Cycle:

FIRST DIGIT OF SERVICE CODE (TENS POSITION) DURING ONE CYCLE
Digits in the tens position of the warning code represents the number of times the light is on 1.2 seconds during one cycle. Note that the light goes off for 1.6 seconds between long and short pulses.

Second Digit Of Service Code (Ones Position) During One Cycle:

SECOND DIGIT OF SERVICE CODE (ONES POSITION)
Digit in the ones position of the warning code represents the number of times the light is on 0.4 seconds during one cycle.