Diagnostic Trouble Codes

[pnkmcneil]

2003 DeVille DTS

Service Engine Soon displays on dash. The DTC display lists all of the systems in order. Do I need to "open" a given system such as PCM or RFA to see actual codes? If so, how do I open it? What does a typical error code look like?

[Cadillac Jim]

On the HVAC console, press <Off> and <Pass Warmer> together and hold them for several seconds, until all the dashboard lights and the message display segments come on, then release them. This puts the DIM in the diagnostic mode. It will poll the modules of the car one by one and either display a message such as "NO ACM CODES" or list the codes for that module. An example is

PCM P0389 HISTORY

Your display may vary, such as PC instead of PCM or H instead of History. The important parts are the module being polled (the P in the code), the four numbers, and whether the code is a HISTORY or CURRENT code. A few codes will have something following the code, usually a number; if you see that, write it down too.

As for the messages that sometimes display such as "ICE POSSIBLE," some export models have a message number as well as the message itself. The number can be used in the owners' manual to find the message in the native language of the export country.

[Ranger]

OFF and PASSENGER WARMER buttons do not apply to this year and model. After you enter the diagnostics with the INFO UP and ON/OFF buttons you can get all codes or toggle through the various sections with the INFO DOWN button and then see those codes only. When doing this the ON/OFF button = Yes and the INFO RESET button = no to the prompts.