No Start Issues

 

ECU Related Issues

Communication Issues?

Check communication with the following ECU’s:

  • ECM/PCM
  • TCM (e.g. park/neutral position signal, …)
  • Anti – Theft ECUs (Immobilizer, Steering Lock, BCM…)
  • Air Bag module (e.g. ‘Crash Signal’ on [Land Rover, Volvo, Mercedes])
    • 📝 No Start | Crash Signal Crash Signal | 2015 Mercedes C350
      • Xentry  → Engine ECU  → Adaptations  → “start disabled due to crash event”
      • This will lift the lock …you may get an error saying it hasn’t completed, ignore it as it has done it (DK)
  • ABS Module
    • On some cars (e.g. 2007 Volvo S80), no communication with the ABS module will result in a no start condition
    • On other cars, ABS can be a part of immobilizer system (e.g. 2019 Honda Accord)
  • Radio Transceiver
    • 📝 No Start | Radio Transceiver Disconnected | 2014 Ford Fusion
      • With radio transceiver module car won’t start and ignition won’t turn on. Its located on headliner.

See also ➱ No Communication with the ECU Troubleshooting Guide

 

Intended Start Prevention?

  • Anti – Theft Related  (Immobilizer)
    • Key Programming, Security Components Matching, Aftermarket Alarm Interference, Remote Shut-off Devices, etc.
  • Safety Related
    • TCM
      • Transmission codes might cause a no-start
      • Park/Neutral Position Switch signal (tells ECM if transmission is in PARK).
    • Air Bag module (e.g. ‘Crash Signal’ on [Land Rover, Volvo, Mercedes])
    • ABS
      • On some cars (e.g. 2007 Volvo S80), no communication with the ABS module will result in a no start condition
      • On other cars, ABS can be a part of immobilizer system (e.g. 2019 Honda Accord)
    • Fail-Safe Mode
      • Hold brake pedal and start button for a minute (e.g. 08′ Prius)
      • Check codes in ECM and TCM
  • Emissions Related
    • DEF (Diesel Exhaust Fluid, e.g. AdBlue)
      • If the DEF system has malfunction, it might start a countdown of remaining starts. That is when you are expected to fix the problem. If not fixed, car will stop starting. Dealer usually has a scan tool option (for a last chance DEF repair) to reset it for another 5 or so starts. If you run out of starts then, you might need to buy a brand new ECM.
    • Exhaust Gas Temperature Sensor codes (e.g. Ford Diesel)
    • Bad/Disconnected Coil might cause a no-start (e.g. 07′ Toyota Sienna)

 


Ignition & Timing

  • ➱ Ignition Troubleshooting
  • ➱ Timing Troubleshooting
    • CKP and CMP sensors signals or their correlation.
    • Note that ECM might not give a code about wrong timing (e.g. 14′ Ford Focus, …)
    • Timing belt or Chain [Loose/ Jumped/ Broken]

Testing: 

 

Air/Fuel Ratio Miscalculation

  • ECT (Engine Coolant Temperature Sensor).
    • ECM uses Engine Coolant Temperature sensor in calculation of air/fuel ratio.
    • 07′ Toyota Sienna. Unplugged ECT can cause a no start.
  • O2 Sensor
    • 15′ Focus 2.0 GDI. Car failed to start (almost started), but felt like it lacked fuel. After the front O2 has been disconnected, started right up.
  • High Side Fuel Pressure Rail Sensor 
    • 2013 Scion FRS. Start and stall scenario. Disconnected front O2, started, but stalled on pressing the gas pedal. After a while it stopped starting at all. After “High Side Fuel Pressure Rail Sensor”  replacement, everything started to work properly.
    • 2013 Jetta TDI

 

Fuel Delivery

Testing:

  • Fuel Pressure Test.

 

Restricted Air Flow

  • Extremely dirty air filter
  • Clogged exhaust

Testing:

  • Visual Inspection of the air filter
  • Intake Manifold Vacuum Test
  • Exhaust Back Pressure Test

 

Mechanical (internal)

  • Low Compression
    • Blown head gasket
      • Note, compression test is inconclusive!  It can have good compression on all cylinder with coolant leaking. Check coolant level, or ask customer he refilled coolant.
    • Bent con rod, worn piston rings
    • Intermittent compression?
  • Seized engine

Testing:

  • Visual Inspection of spark plugs
  • Compression Test
  • Cylinder Leak Down Test

 

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