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Es250 Ground Circuits

  1. Ensure ignition is off. Disconnect connectors from ECU. Remove locks so ECU connectors can be easily backprobed. See Figure. Reconnect ECU connectors.
  2. Using an ohmmeter, check for continuity to ground on ECU terminals E1, E01 and E02. See Figure. Resistance should be zero ohms. If resistance is not zero ohms, repair open to ground.
  3. Using a DVOM, touch negative lead of voltmeter to a good ground. Touch positive lead of voltmeter to each ground terminal. With vehicle running, voltmeter should indicate less than one volt. If voltmeter reading is greater than one volt, check for open, corrosion and loose connection on ground lead.
NOTE: For testing LS400 power circuit, refer to ECU POWER SOURCE CIRCUIT, BACK-UP POWER SOURCE CIRCUIT and TERMINAL TE1 & TE2 CIRCUIT diagnosis charts at end of article. See CIRCUIT DIAGNOSIS CHARTS .
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