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DTC U2151: Navigation Display Serial Data High/Low Circuit: Testing

WARNING: This page is about a different car, the 2001 Cadillac Seville. However, it is still accessible from the selected car via links, so may be relevant.
  1. If navigation system diagnostic system check has been performed, go to next step. If navigation system diagnostic system check has not been performed, perform NAVIGATION SYSTEM DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM.
    2. NOTE: Communications circuits are not at a constant steady voltage level.
  2. Turn ignition switch to OFF position. Disconnect Navigation Display Head (NDH) 32-pin harness connector. NDH is located in overhead console. Turn ignition switch to RUN position. Measure voltage between ground and NDH harness connector terminals C12 (Red wire) and D12 (Brown wire), individually. See Figure . Ignoring polarity, voltage should be 2-3 volts at both terminals. If voltage is not as specified, go to next step. If voltage is as specified, go to step  6 .
  3. Inspect Red wire and Brown wire for an open, short to ground, short to voltage or shorted together between NDH harness connector and navigation data processor. If problem does not exist, go to next step. If problem exists, repair Red wire and/or Brown wire as necessary. After repair, go to step  8 .
  4. Inspect Navigation Module (NAV) harness connector for poor connections. If problem does not exist, go to next step. If problem exists, repair NAV harness connector as necessary. After repair, go to step  8 .
  5. Replace NAV, then go to step  8 .
  6. Inspect NDH harness connector for poor connections. If problem does not exist, go to next step. If problem exists, repair NDH harness connector as necessary. After repair, go to step  8 .
  7. Replace NDH, then go to next step.
  8. Using scan tool, clear DTCs. Turn ignition switch to OFF position. Disconnect scan tool. Open and close driver's door to cancel retained accessory power mode. DO NOT operate any system for 2 minutes. Turn ignition switch to RUN position. Wait 20 seconds, then connect scan tool. Using scan tool, retrieve DTCs. If DTC resets, repeat test beginning at step  2 .
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