Diesel Diagnostic Check - Tester Check
This check determines if the ECM is capable of detecting a fault in the DEC system. Prior to any diagnostics, correct operation of the tester must be verified.
NOTE:
The following step numbers refer to the numbers in the accompanying flow chart(s).
- This step checks to see if the tester is supplied with 12 volts. With power cord installed, light should glow.
- This step determines if the ALDL circuit is grounded or faulty. When the tester is connected to the ALDL connector, the "CHECK ENGINE" light (CEL) should remain on.
- When ignition is turned on, the CEL should remain on. If not, ECM may be shorted internally. The normal ECM reset time is 10 seconds. Therefore, when the tester is used during diagnostics, the CEL will flicker when function knob is rotated.