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Home >> Mazda >> 2002 >> Tribute LX, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 27 (Engine Controls - Self-Diagnostics - 2.5L) >> Diagnostic Tests >> DTC P0850: Neutral Switch Input Circuit Malfunction >> Diagnosis & Repair Procedure

Diagnosis & Repair Procedure

WARNING: This page is about a different car, the 2002 Mazda 626. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ensure FREEZE FRAME DATA has been recorded. Check for related service bulletins. Repair as necessary and go to next step.
  2. Start engine. Using scan tool, check NDSFLG V PID data. Move shift lever between Neutral and other positions while observing NDSFLG V PID data. NDSFLG V PID should indicate about zero volts when shift lever is in Neutral position and 5 volts when shift lever is in any other position. If NDSFLG V PID is as specified, problem is intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article. If NDSFLG V PID indicates about 5 volts continuously, go to next step. If NDSFLG V PID indicates about zero volts continuously, go to step  5 .
  3. Turn ignition off. Disconnect neutral switch connector. Check for loose, damaged or corroded connector terminals. Repair as necessary, and go to step  7 . If connector terminals are okay, go to next step.
  4. Turn ignition on. Measure voltage between ground and neutral switch harness connector terminal "A" (Light Green/Black wire). If about 5 volts is present, go to next step. If about 5 volts is not present, repair open in Light Green/Black wire between neural switch and PCM. See WIRING DIAGRAMS article. Repair as necessary and go to step  7 .
  5. Turn ignition off. Using scan tool, check NDSFLG V PID data. Connect a fused jumper wire between neutral switch connector terminals. If NDSFLG V PID changes from about zero to about 5 volts, go to next step. If NDSFLG V PID does not change, repair open in Black/Yellow wire between neutral switch and PCM. See WIRING DIAGRAMS article. Repair as necessary and go to step  7 .
  6. Check for continuity between neural switch connector terminals while moving shift lever in and out of Neutral. If continuity is present with shift lever in Neutral position and is not present with shift lever out of Neutral position, go to next step. If continuity is not as specified, replace neutral switch and go to next step.
  7. Reconnect all connections. Start engine. Clear DTCs. See CLEARING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. Drive vehicle at speeds less than 16 MPH. Move shift lever through all gear positions, including Neutral. Check for DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. If DTC P0850 is present, replace PCM and go to next step. See REMOVAL, OVERHAUL & INSTALLATION article. On vehicles equipped with immobilizer system, reprogram ignition key identification numbers. See COMPUTER RELEARN PROCEDURES - IMPORT article in GENERAL INFORMATION. If DTC P0850 is not present, go to next step.
  8. Perform DTC confirmation procedure. See DTC CONFIRMATION PROCEDURE  under SELF-DIAGNOSTIC SYSTEM. Check for DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. If any other DTC is present, go to appropriate test.
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