DDC Tester Check
The Diesel Diagnostic Check (DDC) Tester (J-34750) is used to check the ECM's ability to detect a fault and set a trouble code. The mode selector assists diagnostics if no code is set.
This test verifies that the DDC tester is operating properly.
NOTE:
The following step numbers refer to the numbers in the accompanying flow chart(s).
- Checks to see if tester is supplied with 12 volts, and if ALCL circuit is grounded or faulty. Normally, when connection is made to ALCL, the Check Engine light (CEL) in the tester should glow.
- When ignition is turned "on", the CEL should remain on. If CEL goes off, ECM may be shorted internally.
NOTE:
When using the DDC tester in any diagnostic mode (3.9K or 10K), the CEL will flicker. This is normal. When switching from a diagnostic mode to Normal or Ground, the CEL will glow steadily for 10 seconds, then go off. This is the normal ECM reset time.