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ECM Power And Ground Circuit Check: Troubleshooting

NOTE:
  • Before performed troubleshooting, be sure to read the Precautions of ECM Circuit Inspection.
  • When measuring circuit voltage, resistance and/or pulse signal at ECM connector, connect the special tool to ECM and/or the ECM connectors referring to INSPECTION OF ECM AND ITS CIRCUITS .
DTC TROUBLESHOOTING CHART

Step Action YES NO
1  Circuit fuse check 
  1. Disconnect connectors from ECM with ignition switch turned OFF.
  2. Check for proper connection to ECM connector at "E23-1", "E23-2", "E23-3", "E23-8", "E23-16", "C37-39", "C37-58", "C37-59", "C37-73", "C37-80" and "C37-81" terminals.
  3. If OK, check "RADIO" fuse and "IG COIL" fuse for blowing.

Are "DOME" fuse and "IG COIL" fuse in good condition? 		 Go to Step 2. Replace fuse (s) and check for short in circuits connected to fuse (s).
2  Power supply circuit check 
  1. Measure voltage between "E23-1" terminal of ECM connector and body ground.

Is voltage 10 - 14 V? 		 Go to Step 3. "WHT" wire is open circuit.
3  Ignition signal check 
  1. Turn ignition switch to ON position.
  2. Measure voltage between "E23-8" terminal of ECM connector and body ground.

Is voltage 10 - 14 V? 		 Go to Step 4. "BLK/WHT" or "BLK/YEL" wire is open circuit.
4  Main relay circuit check 
  1. Turn ignition switch to OFF position.
  2. Check "FI" fuse (1) in fuse box No. 2 for blowing.
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  1. 3) If OK, measure voltage between "E23-16" terminal of ECM connector and body ground.

Is voltage 10 - 14 V? 		 Go to Step 5. Go to Step 9.
5  Main relay circuit check 
  1. Connect connectors to ECM with ignition switch turned OFF.
  2. Turn ignition switch to ON position.
  3. Measure voltage between "E23-16" terminal of ECM connector and body ground.

Is voltage 0 - 1 V? 		 Go to Step 7. Go to Step 6.
6  ECM ground circuit check 
  1. Turn ignition switch to OFF position.
  2. Disconnect connectors from ECM.
  3. Measure resistance between each "C37-39", "C37-58", "C37-59", "C37-73", "C-37-80" and "C37-81" terminals of ECM connector and body ground.

Is resistance 1 Ω or less? 		 Substitute a known-good ECM and recheck. "BLK/ORN" or "BLK/YEL" wire is open or high resistance circuit.
7  Main relay circuit check 
  1. Disconnect connectors from ECM with ignition switch turned OFF.
  2. Using service wire, ground "E23-16" terminal of ECM connector and measure voltage between each "E23-2" and "E23-3" terminals of ECM connector and body ground.

Is voltage 10 - 14 V? 		 Go to Step 11. Go to Step 8.
8  Main relay circuit check 
  1. Remove main relay (1) from fuse box No. 2. Expand image
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  1. 2) Check for proper connection to main relay connector at "BLU/BLK" and "BLK/RED" wire terminals.
  2. 3) If OK, measure resistance between each "E23-2" and "E23-3" wire terminals of ECM connector and "BLU/BLK" wire terminal of main relay connector.

Is resistance 1 Ω or less? 		 Go to Step 9. "BLU/BLK" wire is open circuit or high resistance circuit.
9  Main relay circuit check 
  1. Remove main relay from fuse box No. 2 with ignition switch turned OFF.
  2. Measure voltage between "BLK/RED" wire terminal of main relay connector and body ground.

Is voltage 10 - 14 V? 		 Go to Step 10. "BLK/RED" wire is open circuit.
10  Main relay check 
  1. Check main relay referring to ENGINE AND EMISSION CONTROL SYSTEM RELAY INSPECTION .

Is main relay in good condition? 		 "BLU" wire is open or high resistance circuit. Replace main relay.
11  Sensor 5 V power source circuit check 
  1. Connect connectors to ECM with ignition switch turned OFF.
  2. Turn ON ignition switch, measure each voltage between "E23-12", "C37-45" and "C37-49" terminal of ECM connector and vehicle body ground.

Is each voltage 4 - 6 V? 		 ECM power and ground circuit is in good condition. Go to Step 12.
12  Sensor 5 V power source circuit check 
  1. Disconnect connectors from ECM, TP sensor, MAP sensor, A/C refrigerant pressure sensor (if equipped with A/C) and EVAP leak check module with ignition switch turned OFF.
  2. Measure each resistance between "E23-12", "C37-45" and "C37-49" terminal of ECM connector and vehicle body ground.

Is each resistance infinity? 		 Check internal short circuit of TP sensor, MAP sensor, A/C refrigerant pressure sensor (if equipped with A/C) and/or EVAP leak check module. "GRY/RED" and/or BLK" wire is shorted to ground circuit.
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