Checking engine control module (ECM) ground terminals

Fig 1: Identifying Ignition OFF Position

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Fig 2: Identifying Connector

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Fig 3: Connecting Control Unit

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• Ignition off.
• Engine speed (RPM) sensor disconnected.
• Check engine control module (ECM) connector and ground terminals 31/32 and 31/33 for contact resistance and oxidation and remedy according to Contact resistance and oxidation .
• Control module connected.

  Connect an ohmmeter between engine speed (RPM) sensor connector terminal 2 (engine control module (ECM) side) and ground.

  Fig 4: Identifying Injector Terminals

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  Fig 5: Identifying Ohms Display

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The ohmmeter should read approximately 0 Ω. 

• OK 

  Refer to Checking signal cable resistance to ground 

• NOT OK 

  Refer to Checking for an open-circuit