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Home >> Mazda >> 2006 >> MX-5 Miata Base >> Repair and Diagnosis >> Engine Performance >> System >> On-Board Diagnostic [Engine Control System] >> DTC P0850 >> Diagnostic Procedure
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Diagnostic Procedure

DTC P0850 DIAGNOSTIC PROCEDURE TABLE

STEP INSPECTION ACTION
1 VERIFY FREEZE FRAME DATA HAS BEEN RECORDED 
  • Has FREEZE FRAME DATA been recorded?
Yes Go to the next step.
No Record the FREEZE FRAME DATA on the repair order, then go to the next step.
2 VERIFY RELATED REPAIR INFORMATION AVAILABILITY 
  • Verify related Service Bulletins and/or on-line repair information availability.
  • Is any related repair information available?
Yes Perform repair or diagnosis according to the available repair information.
  • If the vehicle is not repaired, go to the next step.
No Go to the next step.
3 CLASSIFY HIGH INPUT OR LOW INPUT 
  • Connect the WDS or equivalent to DLC-2.
  • Access CPP/PNP PID.
  • Verify CPP/PNP PID when gear is neutral position.
  • Is CPP/PNP PID always off?
Yes Go to the next step.
No Go to Step 10.
4 INSPECT NEUTRAL SWITCH CONNECTOR FOR POOR CONNECTION 
  • Turn the ignition switch off.
  • Disconnect neutral switch connector.
  • Inspect for poor connection (such as damaged/pulled-out pins, corrosion).
  • Is there any malfunction?
Yes Repair or replace the terminal, then go to Step 14.
No Go to the next step.
5 CLASSIFY NEUTRAL SWITCH OR CIRCUIT 
  • Connect the WDS or equivalent to the DLC-2.
  • Access CPP/PNP PID.
  • Connect a jumper wire between neutral switch terminal 1A and 2A.
  • Is CPP/PNP PID on?
Yes Go to the next step.
No Go to Step 7.
6 INSPECT NEUTRAL SWITCH  Yes Go to Step 14.
No Replace the neutral switch, then go to Step 14.
7 INSPECT NEUTRAL SWITCH GROUND CIRCUIT FOR OPEN CIRCUIT 
  • Inspect for continuity between neutral switch terminal 1A and ground.
  • Is there continuity?
Yes Go to the next step.
No Repair or replace the neutral switch ground circuit for an open circuit, then Go to Step 14.
8 INSPECT PCM CONNECTOR FOR POOR CONNECTION 
  • Turn the ignition switch off.
  • Disconnect the PCM connector.
  • Inspect for poor connection (such as damaged/pulled-out pins, corrosion).
  • Is there any malfunction?
Yes Repair or replace the terminal, then go to Step 14.
No Go to the next step.
9 INSPECT NEUTRAL SWITCH SIGNAL CIRCUIT FOR OPEN CIRCUIT 
  • Inspect for continuity between neutral switch terminal 2A and PCM terminal 1X.
  • Is there continuity?
Yes Repair or replace the wiring harness for an open circuit, then go to Step 14.
No Go to Step 14.
10 INSPECT NEUTRAL SWITCH CONNECTOR FOR POOR CONNECTION 
  • Turn the ignition switch off.
  • Disconnect the neutral switch connector.
  • Inspect for poor connection (such as damaged/pulled-out pins, corrosion).
  • Is there any malfunction?
Yes Repair or replace the terminal, then go to Step 14.
No Go to the next step.
11 CLASSIFY NEUTRAL SWITCH OR CIRCUIT 
  • Connect the WDS or equivalent to DLC-2.
  • Access CPP/PNP PID.
  • Verify that CPP/PNP PID changes from ON to OFF when the neutral switch connector disconnected.
  • Does CPP/PNP PID change from ON to OFF?
Yes Go to the next step.
No Go to Step 13.
12 INSPECT NEUTRAL SWITCH  Yes Go to Step 14.
No Replace the neutral switch, then go to Step 14.
13 INSPECT NEUTRAL SWITCH SIGNAL CIRCUIT FOR SHORT TO GROUND 
  • Inspect for continuity between neutral switch terminal 2A and ground.
  • Is there continuity?
Yes Repair or replace the wiring harness for short to ground, then go to the next step.
No Go to the next step.
14 VERIFY TROUBLESHOOTING OF DTC P0850 COMPLETED 
  • Make sure to reconnect all disconnected connectors.
  • Start the engine.
  • Clear the DTC from the PCM memory using the WDS or equivalent.
  • Drive the vehicle above 30 km/h {19 mph}  and stop vehicle.
  • Depress and release the clutch pedal more than 10 times  during drive cycle.
  • Is the PENDING CODE for this DTC present?
Yes Replace the PCM, then go to the next step.
(See PCM REMOVAL/INSTALLATION .)
No Go to the next step.
15 VERIFY AFTER REPAIR PROCEDURE  Yes Go to the applicable DTC troubleshooting.
(See DTC TABLE  .)
No Troubleshooting completed.