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Reading the Cadillac Onboard Diagnostic Codes

If you have a problem, why not ask the Cadillac what's wrong?

Question markOne wonderful feature of most Cadillacs, including the Deville / DTS, the Seville / STS, and the Catera / CTS up to 2003, and the Allante, is the availability of onboard diagnostics.
By pressing a set key sequence on the dash, the Cadillac will display any trouble codes, warnings, or watch conditions being monitored by any of the various control systems.  These trouble codes are called Diagnostic Trouble Codes (DTC), and are shown by system. 
You can reset the codes using the onboard diagnostics, and in some cases make changes to the way that the vehicle operates.  This article addresses the basics of how to get in to the system, back out of the system, and use some of the info found there.  Please see the How-To section for more information.

DTC display; 1998-2004 Seville and 2000-2005 Deville

by JimD

Use the 3 switches located to the right of the Driver Information Center (DIC) to activate and respond to the OBD prompts on the DIC.

INFO RESET  =  NO     
INFO DOWN  or  INFO UP   =  manual toggle

Ignition ON, acknowledge any warning messages; press ON/OFF and INFO UP  together for 2 to 3 seconds. Everything in front of you lights up for 4 or 5 seconds, then you will see:

Display  shows "ALL?"

Answering YES will display "ALL CODES?"
Answering YES will run automatic test sequence and display codes, if any. Systems and codes will scroll faster than I am able to read them and write them; not to worry.
"ALL CLEAR CODES?" will display at the end of the automatic test.  If you are satisfied you have the information you need,  answer YES to clear/erase all error codes.
Answering  "ALL?" with INFO DOWN will toggle systems test manually in order.
Answering  "ALL?" with INFO UP will toggle system test manually in reverse order.
Press INFO RESET to reset DIC to "ALL?" to start again.
Ignition OFF to exit.

 SYSTEMS: (as of 1998)

ABS (Antilock Brake System)
AMP (Amplifier)
DDM (Door Driver Module)
DIM (Dash Integration Module)
IPC (Instrument Panel Cluster)
IPM (Instrument Panel Module)
IRC (Integrated Radio Module)
PCM (Powertrain Control Module)
RFA (Remote Function Actuation)
RIM (Rear Integration Module)
SDM (Sensing and Diagnostic Module) Includes airbag crash data. Under RF seat of Seville.
VTD (Vehicle Theft Deterrent)
MSM (Memory Seat Module)
TTM (Tilt/Telescoping Module)
RSS (Road Sensing Suspension)

DTC display 1989-2000:

1. Turn the ignition switch ON. [Bruce notes: interestingly, the engine can be on or off]

2. On the cars up to 1995, on the Climate Control panel, press the OFF and WARM buttons simultaneously.

    On the 96/97, push the OFF button and the top (warmer) end of the PASS rocker switch.

    For 99 Deville, Turn the ignition switch to ON. Simultaneously press the following buttons until all VF display segments (IPC and CCP) are illuminated:
    The digital IPC, the climate control center (CCC) OFF and warmer (RED) buttons
    The analog IPC, the climate control panel (CCP) OFF and PASS warmer (up arrow) buttons

    On the 98-2000, there seems to be some discussion:

        GM ESI CD version:

  • 1) Turn the ignition on, engine off. 2) Press the RESET button to acknowledge any warning messages present 3) Press the OPTIONS button on the driver information center and hold 4) While pressing the OPTIONS button, press the FUEL button 4 times within a 10 second 
    period.  System will first enter automatic display mode followed by manual display mode.

    Willy Spenser writes how to really do it for the 98+:
  • With the ignition key on, running or not makes no difference, press the on/off and info^(info/up) buttons for the DIC at the same time for about 2-3 seconds and release. It should then be itn the DTC check mode. Use the on/off button to select,when it
    lists a question,i.e CODES?...,press on/off button to select that. The codes for each system will now appear if there are any. Otherwise it will say NO RSS, NO PCM,ETC... Use the reset info button to return or go back to the previous selection. When it asks you CLEAR CODES?...press the on/off button to clear them IF YOU WANT THEM CLEARED, if no, press reset info repeatedly until you exit. You can also exit by turning the ignition switch off.
    This should work on '98 and up Sevilles.

3. Hold the buttons depressed until all display segments on the CC/DIC and instrument Panel Cluster (IPC) illuminate. On 1992 models, a separate combination panel houses both the ECC and DIC. On 1993-1994 models, the DIC is part of the instrument panel cluster.

4. After the segment check, the diagnostic trouble codes will be displayed. Each trouble code consists of the system identifier, a three-digit code identifier and the current or history identifier. If no codes are present for a system, a NO X CODE or NO X DATA message will be displayed.

  • E -- ECM trouble code
  • P -- PCM trouble code
  • C -- Current trouble code
  • H -- History trouble code
  • NO X CODE -- No code present (X represents the system)
  • NO X DATA -- Communication lines are not operating (X represents the system)
2003 CTS:
For the 2003 CTS Non-Nav, turn on the ignition without starting the car. Push in the F1 and the F6 function keys on the radio at the same time.
For the 2003 CTS with Nav, Press the BAND button and the bottom NAV button to the left of the display, then release.
Does not work on 2004+ models, which require a code reader.


The segment check is the illumination of the IPC, CCP, and DIC to verify that all segments of the liquid crystal displays [The display is actually florescent, not liquid crystal, but the GM text says LCD] are working. Only the turn signal indicators do not light during this check. Diagnosis should not be attempted unless all segments appear, as this could lead to misdiagnosis. If any portions or segments are inoperative, the faulty component should be replaced.


When the system is placed into the Diagnostic Mode, the lighting elements on the climate control panel are used as status lights for various components. The mode of operation is determined by the light being ON or OFF. The use of each lighting element is different in ECM or BCM mode. For example, in the ECM mode the word OFF on the CCP will light to indicate a rich condition sensed by the left oxygen sensor input. In BCM mode, the same light is ON when the BCM commands the air inlet valve to the recirculate position.


After diagnostics is entered, any fault codes stored in computer memory will be displayed. For 1992 systems, codes may be stored or the ECM, BCM or SIR systems. For 1993-1994 the system has been expanded to include codes for the PCM, IPC, ACP, SIR, TCS, and RTD systems The Instrument Panel Cluster (IPC) replaces the BCM for 1993-1994 models, but serves the same purpose. ACP, SIR, TCS, and RTD stand for Air Conditioning Programmer, Supplemental Inflatable Restraint, Traction Control System, and Real Time Dampening, respectively. We will only deal with Engine control malfunctions here.

Each trouble code consists of the system identifier (E for ECM or P for PCM), a three-digit code identifier and the letter C or H to indicate current or history codes. If no codes are present for a system, a NO X CODE message will be displayed, with X representing the system.

On 1992 models, the RESET/RECALL button on the DIC will terminate diagnostics and return the vehicle to normal operation. For 1993+, depress the AUTO button on the ECC panel to return to normal operation.

List of 1999 DTC Codes
List of 2003 DTC Codes

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