Does not have spark at the coils

Tiny
FRANK LOPEZ2
  • MEMBER
  • 2002 NISSAN SENTRA
  • 1.8L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 120,000 MILES
Good evening, is it still necessary to make the resistance test from the ECM and harness connector? Is this also the correct way to check is there is a signal pulse from let's say the crank sensor or the ignition coil connector to the computer? I am thinking I do not have spark at the coils due to having a weak signal because I have power and ground. Thank you.
Friday, October 7th, 2016 AT 10:29 PM

1 Reply

Tiny
AL514
  • MECHANIC
  • 4,127 POSTS
Here is a diagram of the crank and cam sensor wiring. The way you want to start is to check the crank sensor for instance, is check for a pulse with a test light on the red wire at the crank sensor plug itself. Back probe the sensor plug while still plugged in with a T pin or such and while cranking the engine check for a pulse on that red wire. The White wire on that plug is power going to the sensor from the ECM relay(Check for power on this wire as well). The black wire is ground. It is the same for the Cam sensor. No crank signal will cause a No Spark condition. Check at the sensor for a pulse before going and messing with the harness from the ECM.
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Saturday, October 8th, 2016 AT 4:19 AM

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