When idling can be continued

Using The M-MDS 

1. Connect the M-MDS to the DLC-2.
2. Warm up the engine.
3. Using the simulation function [VLV_TIMING_DSD_EX], verify that the engine speed fluctuates when the OCV duty value is 100%. (See SIMULATION INSPECTION .) If the engine speed fluctuates, verify the condition of the timing chain assembly (valve timing). If the engine speed does not fluctuate, perform the following inspections.
   1. OCV coil resistance inspection and spool valve operation inspection. (See COIL RESISTANCE INSPECTION .) (See Spool Valve Operation Inspection .)
   2. Inspect the following wiring harnesses and connectors between the OCV and PCM for an open and short circuit.
      • Between OCV terminal A and PCM terminal 1CO
      • Between OCV terminal B and F12 15A fuse, and F12 15 fuse and main relay terminal C
   3. Inspect the oil passage for clogging and leakage.

      Oil passage 

      • Between engine oil solenoid valve and OCV
      • Between OCV and camshaft
      • Oil passage inside camshaft
4. If the inspection items are normal, replace the hydraulic variable valve timing actuator. (See ELECTRIC VARIABLE VALVE TIMING MOTOR/DRIVER REMOVAL/INSTALLATION .)

Without Using the M-MDS 

1. Disconnect the OCV connector.
2. Start the engine and idle it.
   NOTE:

   • When applying battery voltage between the OCV terminals, the positive and negative cables can be connected to either terminal A or B.
3. Verify that the engine idles roughly or stalls when battery voltage is applied between OCV terminals A and B.

   Courtesy of MAZDA MOTORS CORP.

If the engine idles roughly or stalls, verify the condition of the timing chain assembly (valve timing). If the engine does not idle roughly or stall, perform the following inspections.

1. OCV coil resistance inspection and spool valve operation inspection (See COIL RESISTANCE INSPECTION .) (See Spool Valve Operation Inspection .)
2. Inspect the following wiring harnesses and connectors between the OCV and PCM for an open and short circuit.
   • Between OCV terminal A and PCM terminal 1CO
   • Between OCV terminal B and F12 15A fuse, and F12 15 fuse and main relay terminal C
3. Inspect the oil passage for clogging and leakage.

   Oil passage 

   • Between engine oil solenoid valve and OCV
   • Between OCV and camshaft
   • Oil passage inside camshaft
4. If the inspection items are normal, replace the hydraulic variable valve timing actuator. (See ELECTRIC VARIABLE VALVE TIMING MOTOR/DRIVER REMOVAL/INSTALLATION .)