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Home >> Mazda >> 2002 >> Tribute LX, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 35 (Automatic Transmission - Diagnosis [GF4A-El]) >> Diagnostic Tests >> DTC P1780: O/D Off Switch Circuit Shorted To Ground Or Open >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2002 Mazda 626 and 2001 Mazda 626. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform continuous memory, KOEO and KOER self-tests to confirm DTC P1780 exists. Turn ignition switch to OFF position. Disconnect O/D OFF switch connector and check connector for damage, pulled out terminals or corrosion. Repair as necessary. If connector is okay, inspect O/D OFF switch continuity. See O/D OFF SWITCH  under COMPONENT TESTS. If O/D OFF switch is okay, go to next step. If O/D OFF switch is faulty, replace O/D OFF switch.
  2. Check for continuity between chassis ground and O/D OFF switch harness connector terminal "B". See Figure. If continuity does not exist, disconnect PCM connector and check for damage, pulled out terminals or corrosion. Repair as necessary. If PCM connector is okay, go to next step.
  3. Check for continuity between O/D OFF switch harness connector terminal "A" and PCM harness connector terminal No. 29. See Figure and Figure . If continuity does not exist, repair open in affected circuit. See WIRING DIAGRAMS . If continuity exists, check for continuity between chassis ground and O/D OFF switch harness connector terminal "A". See Figure. If continuity exists, repair short to ground in affected circuit between O/D OFF switch and PCM. See WIRING DIAGRAMS . If continuity does not exist, check connectors, terminals and wiring harnesses for intermittent concern. Go to next step.
  4. Road test vehicle, ensuring transaxle shifts smoothly through all gears. Go to next step.
  5. Bring vehicle to a gradual stop. Perform self-test on PCM and ensure serviced DTC does not repeat. If serviced DTC resets, repeat previous step. If serviced DTC resets again, replace PCM.
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