DESCRIPTION & OPERATION
| WARNING | Vehicles are equipped with air bag supplemental restraint system. Before attempting any repairs involving steering column, instrument panel or related components, see SERVICE PRECAUTIONS and DISABLING & ACTIVATING AIR BAG SYSTEM in appropriate AIR BAG RESTRAINT SYSTEMS article. |
| CAUTION | When battery is disconnected, vehicle computer and memory systems may lose memory data. Driveability problems may exist until computer systems have completed a relearn cycle. See COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION before disconnecting battery. |
There are 2 data lines that can be accessed with a scan tool. The 800 circuit is the PCM data line. It allows the PCM, inflatable restraint diagnostic energy reserve module (SDM), trip computer (Gran Prix), CJ2 model HVAC control and Electronic Brake Control Module (EBCM) to communicate by transmitting data. The 835 circuit is the data line that the radio and HVAC communicates on. The theft deterrent module will ground the 728 circuit if it malfunctions. A scan tool can be connected to the DLC, allowing the scan tool to communicate with the 2 data lines. System operations can then be monitored for diagnostic purposes.
COMPONENT LOCATIONS
| Component | Location |
|---|---|
| Data Link Connector (DLC) | Below Driver's Side Of Instrument Panel |
| Diagnostic Energy Reserve Module (SDM) | Below Front Passenger Seat. (Scheme 1) |
| Electronic Brake Control Module (EBCM) | Behind Driver Side Of Instrument Panel, Left Side Of Mag Bracket. (Scheme 2) |
| HVAC Control | Center Of Instrument Panel |
| Powertrain Control Module (PCM) | Driver Side Of Engine Compartment, Forward Of Strut Tower. (Scheme 3) |
| Radio | Center Of Instrument Panel |
| Theft Deterrent Module | Behind Passenger Side Of Instrument Panel, Above Instrument Panel Compartment. (Scheme 1) |
| Trip Computer (Grand Prix) | Driver Side Of Instrument Cluster. (Scheme 1) |
| C100 (36 Terminals) | Passenger Side Of Dash, Behind Strut Tower. (Scheme 4) |
| G201 | Behind Instrument Panel, On Passenger Side Of Brake Pedal Bracket. (Scheme 2) |
| S211 (Lumina & Monte Carlo) | Instrument Panel Harness, Near C202 Breakout |
| S211 (Grand Prix) | Instrument Panel Harness, Near Instrument Panel Breakout |
| S211 (Regal) | Engine Harness, Near EBCM Breakout |
| S211 (Cutlass Supreme) | Instrument Panel Harness, Near Radio Breakout |
| S225 (CJ2 HVAC) | Instrument Panel Harness, Near Radio Breakout |
| S237 (Lumina & Monte Carlo) | Instrument Panel Harness, Near Instrument Panel Compartment Lamp Breakout |
| S237 (Cutlass Supreme & Grand Prix) | Instrument Panel Harness, Near Radio Breakout |
| S237 (Regal) | Instrument Panel Harness, Near C200 Breakout |
COMPONENT LOCATIONS
Scheme 1
Scheme 2
Scheme 3
Scheme 4
PRELIMINARY INSPECTION
Visually inspect for obvious signs of mechanical and electrical damage. Inspect for blown fuses and damaged relays. Inspect for loose or corroded connections, damaged wiring harnesses and/or switches. Check for a broken or partially broken wire inside insulation, which could cause system malfunction but prove good in a continuity/voltage check with system disconnected. These circuits may be intermittent or resistive when loaded and should be checked by monitoring the voltage drop with the system under load. Ensure any aftermarket electronic equipment is properly installed. If fault is found, repair as necessary.
PCM DATA LINE
- If all components are not accessible with a scan tool, check for an open in circuit 800 between DLC terminal "M" and splice S237. See «WIRING DIAGRAMS»(/chevrolet/lumina/i-1989-2001/remont/communication-devices/#data-link-communications-system) .
- If a single component is not accessible with a scan tool, check for an open in circuit 800 between S237 and the component. If the wire is good, see «DATA LINE DIAGNOSIS»(/chevrolet/lumina/i-1989-2001/remont/communication-devices/#data-link-communications-system__data-line-diagnosis) under SYSTEM TESTS article.
ENTERTAINMENT & COMFORT DATA LINE
- If all components are not accessible with a scan tool, check the Dark Green 835 circuit wiring for an open between the DLC connector terminal "J" and S225. See «WIRING DIAGRAMS»(/chevrolet/lumina/i-1989-2001/remont/communication-devices/#data-link-communications-system) .
- If only a single component cannot be accessed with a scan tool, check for an open in the 835 circuit between the component and S225. Repair wiring as necessary. If no fault is found, go to «DATA LINE DIAGNOSIS»(/chevrolet/lumina/i-1989-2001/remont/communication-devices/#data-link-communications-system__data-line-diagnosis) under SYSTEM TESTS.
CONNECTOR IDENTIFICATION
To identify Data Link Connector (DLC) terminals (Scheme 5)
Scheme 5
DATA LINE DIAGNOSIS
For data line diagnosis, refer to flowchart. (Scheme 6)and (Scheme 7).
