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Home >> Geo >> 1996 >> Prizm Base, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Circuit Tests >> Circuit Test B2-4 - No Communication From Data Link Connector >> Diagnosis & Repair

Diagnosis & Repair

  1. Connect scan tool to DLC. Turn ignition on. If scan tool powers up, go to next step. If scan tool does not power up, go to step 3).
  2. Disconnect scan tool. Using a test light connected to ground, probe terminal No. 2 of DLC. See Figure. If test light does not come on, go to step 4). If test light comes on, go to step 5).
  3. Using a test light connected to ground, probe terminal No. 16 of DLC. If test light comes on, go to step 6). If test light does not come on, go to step 7).
  4. Using a test light connected to battery positive, probe terminal No. 2 of DLC. If test light does not come on, go to step 8). If test light comes on, go to step 9).
  5. Check serial data circuit (Black wire) for short to power between DLC terminal No. 2 and PCM. Repair as necessary. If wire is okay, replace PCM. Retest system.
  6. Using a test light connected to battery positive, probe terminals No. 4 and 5 of DLC. If test light comes on at both terminals, scan tool is faulty. If test light does not come on at both terminals, repair open in DLC ground circuits.
  7. Check for blown OBD-II fuse (7.5-amp). If fuse is okay, repair open or short to ground in DLC battery feed circuit (White wire) between DLC and ignition switch. Retest system.
  8. Check for open in Black wire between DLC terminal No. 2 and PCM. Repair as necessary. If wire is okay, reconnect scan tool to DLC. If scan tool communicates with PCM, system is okay at this time. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK . If scan tool does not communicate with PCM, go to step 10).
  9. Check Black wire for short to ground between DLC terminal No. 2 and PCM. Repair as necessary. If wire is okay, replace PCM. Retest system.
  10. Connect scan tool to another vehicle and check operation. If scan tool works properly, replace PCM. Retest system. If scan tool does not work properly, scan tool is faulty.
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