Test 1A - Identifying Vehicle Communication Problems
Connect scan tool to Data Link Connector (DLC) to retrieve 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 terminal No. 4. Ensure 12 volts exists at DLC terminal No. 16. Try another scan tool and/or cable. See BUS FAULT MESSAGES table and proceed to appropriate test number.
BUS FAULT MESSAGES
| Fault Messages | Test No. |
|---|---|
| BUS SHORT TO BATTERY | TEST 4A |
| BUS SHORT TO 5 VOLTS | TEST 5A |
| BUS SHORT TO GROUND | TEST 6A |
| BUS (+) & BUS (-) SHORTED TOGETHER | TEST 7A |
| NO TERMINATION | TEST 8A |
| BUS BIAS LEVEL TOO LOW | TEST 9A |
| BUS BIAS LEVEL TOO HIGH | TEST 9A |
| NOT RECEIVING BUS MESSAGES CORRECTLY | TEST 10A |
| NO BUS BIAS | TEST 11A |
| BUS (+) OPEN | TEST 12A |
| BUS (-) OPEN | TEST 12A |
| BUS (+) & BUS (-) OPEN | TEST 12A |
NO RESPONSE DIAGNOSIS
| Problem Module | Test No. |
|---|---|
| Air Bag Control Module | TEST 2A |
| Powertrain Control Module | TEST 3A |
| Central Timer Module | TEST 13A |
| Compass Mini-Trip System | TEST 14A |