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
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)
TROUBLE CODE DISPLAY
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.