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Symptom Troubleshooting Index

When the vehicle has one of these symptoms, check for a diagnostic trouble code (DTC) with the HDS. If there is no DTC, do the diagnostic procedure for the symptom, in the sequence listed, until you find the cause.

Symptom Diagnostic procedure Also check for
Engine will not start (MIL works OK, no DTCs set)
  1. Test the battery (see BATTERY TEST ).
  2. Test the starter (see STARTER PERFORMANCE TEST ).
  3. Check the fuel pressure (see FUEL PRESSURE TEST ).
  4. Troubleshoot the fuel pump circuit (see FUEL PUMP CIRCUIT TROUBLESHOOTING ).
  • Low compression
  • No ignition spark
  • Restricted exhaust system
  • Intake air leaks
  • Locked up engine
  • Broken timing belt
  • Fuel contamination
Engine will not start (MIL comes on and stays on, no DTCs set) Troubleshoot the DLC circuit (see DLC CIRCUIT TROUBLESHOOTING ).
  • No power to ECM/PCM
  • No ground to ECM/PCM
MIL comes on and stays on, or never comes on at all, no DTCs set Troubleshoot the MIL circuit (see MIL CIRCUIT TROUBLESHOOTING ).  
Engine will not start (MIL works OK, no DTCs set, immobilizer indicator stays on or flashes) Check the immobilizer system:
  
Engine starts but stalls immediately (MIL works OK, no DTCs set, immobilizer indicator stays on or flashes) Check the immobilizer system:
  
Engine is hard to start (MIL works OK, no DTCs set)
  1. Test the battery (see BATTERY TEST ).
  2. Check the fuel pressure (see FUEL PRESSURE TEST ).
  3. Clean the throttle body (see THROTTLE BODY CLEANING ).
  • Low compression
  • Intake air leaks
  • Fuel contamination
  • Weak spark
  • Low fuel pressure
Cold fast idle too low (MIL works OK, no DTCs set)
  1. Do the ECM/PCM idle learn procedure (see ECM/PCM IDLE LEARN PROCEDURE ).
  2. Check the idle speed (see IDLE SPEED INSPECTION ).
  3. Clean the throttle body (see THROTTLE BODY CLEANING ).
  
Cold fast idle too high (MIL works OK, no DTCs set)
  1. Do the ECM/PCM idle learn procedure (see ECM/PCM IDLE LEARN PROCEDURE ).
  2. Check the idle speed (see IDLE SPEED INSPECTION ).
  3. Do the throttle position learning check (see THROTTLE BODY TEST ).
 Intake air leaks
Idle speed fluctuates (MIL works OK, no DTCs set)
  1. Do the ECM/PCM idle learn procedure (see ECM/PCM IDLE LEARN PROCEDURE ).
  2. Check the idle speed (see IDLE SPEED INSPECTION ).
  3. Do the carbon accumulation check (see THROTTLE BODY TEST ).
  4. Troubleshoot the A/C signal circuit (see A/C SIGNAL CIRCUIT TROUBLESHOOTING ).
  • Incorrect valve timing or clearance adjustment
  • Intake air leaks
After warming up, idle speed is below specification without load (MIL works OK, no DTCs set)
  1. Troubleshoot the alternator FR signal circuit (see ALTERNATOR FR SIGNAL CIRCUIT TROUBLESHOOTING ).
  2. Do the carbon accumulation check (see THROTTLE BODY TEST ).
 Incorrect valve adjustment
After warming up, idle speed is above specification without load (MIL works OK, no DTCs set)
  1. Troubleshoot the alternator FR signal circuit (see ALTERNATOR FR SIGNAL CIRCUIT TROUBLESHOOTING ).
  2. Inspect the APP sensor (see APP SENSOR SIGNAL INSPECTION ).
 Intake air leaks
Low power (MIL works OK, no DTCs set) Check the fuel pressure (see FUEL PRESSURE TEST ).
  • Low compression
  • Incorrect camshaft timing
  • Incorrect engine oil level
  • Exhaust restriction
Engine stalls (MIL works OK, no DTCs set)
  1. Do the ECM/PCM idle learn procedure (see ECM/PCM IDLE LEARN PROCEDURE ).
  2. Check the fuel pressure (see FUEL PRESSURE TEST ).
  3. Check the idle speed (see IDLE SPEED INSPECTION ).
  4. Troubleshoot the brake pedal position switch signal circuit (see BRAKE PEDAL POSITION SWITCH SIGNAL CIRCUIT TROUBLESHOOTING ).
  • Intake air leaks
  • Faulty harness and sensor connections
Difficult to refuel (MIL works OK, no DTCs set)
  1. Check the fuel vent tube between the EVAP canister and the fuel tank.
  2. Check the fuel tank vapor recirculation tube between the fuel pipe and the fuel tank.
  3. Replace the fuel tank:
Malfunctioning gas station filling nozzle
Fuel overflows during refueling (No DTCs set) Replace the fuel tank.
 Malfunctioning gas station filling nozzle
Fuel cap warning message stays on (MIL works OK, no DTCs set) Troubleshoot the fuel cap warning message system (see FUEL CAP WARNING MESSAGE SYSTEM TROUBLESHOOTING ).  
HDS does not communicate with the ECM/PCM or the vehicle Troubleshoot the DLC circuit (see DLC CIRCUIT TROUBLESHOOTING ). Correct HDS software
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