Test 1A: Identifying Vehicle Communication Problems
Connect scan tool to Data Link Connector (DLC) to retrieve Diagnostic Trouble Codes (DTC) and bus failure messages. If scan tool message is blank, see NO RESPONSE DIAGNOSIS table and proceed to appropriate test number. Disconnect scan tool. Ensure ground circuit has continuity at DLC terminals No. 4 and 5. Ensure 12 volts is present at DLC terminal No. 16. Try another scan tool and/or cable. See NO RESPONSE DIAGNOSIS , BUS FAULT MESSAGES and BUS SYMPTOMS tables and proceed to appropriate test number.
NO RESPONSE DIAGNOSIS
| Problem Module | Test No. | ||
|---|---|---|---|
| Air Bag Control Module (ACM) | 2A | ||
| Automatic Temperature Control (ATC) | 3A | ||
| Body Control Module (BCM)(1) | 4A | ||
| Anti-Lock Brake Module | 5A | ||
| Mechanical Instrument Cluster (MIC) | 6A | ||
| Memory Heated Seats (MHS) | 7A | ||
| Overhead Traveler Information System (OTIS) | 8A | ||
| Powertrain Control Module (PCM) | 9A | ||
| Radio | 10A | ||
| Sentry Key Immobilizer (SKIM) | 11A | ||
| Transmission Control Module (TCM) | 12A | ||
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BUS FAULT MESSAGES
| Fault Messages | Test No. |
|---|---|
| BUS SHORT TO BATTERY | 13A |
| BUS SHORT TO GROUND | 14A |
BUS SYMPTOMS
| Symptom Messages | Test No. |
|---|---|
| Odometer Displays NO BUS | 15A |
| No Fused Ignition Switch Output To BCM | 16A |