How to Troubleshoot Circuits at the ECM/PCM Connectors

NOTE: The ECM/PCM overwrites data and monitors the EVAP system for about 40 minutes after the ignition switch is turned to LOCK (0), or the engine start/stop button is pressed to select the OFF mode. Jumping the SCS line after turning the ignition switch to LOCK (0), or pressing the engine start/stop button to select OFF mode cancels this function. Disconnecting the ECM/PCM during this function, without jumping the SCS line first, can damage the ECM/PCM.

Jump the SCS line with the HDS.
Disconnect ECM/PCM connectors A, B, and C.
NOTE: ECM/PCM connectors A, B, and C have symbols (A=□, B=Δ, C=◦) embossed on them for identification.

Fig 1: Identifying ECM/PCM Connectors A, B And C
Courtesy of AMERICAN HONDA MOTOR CO., INC.
When diagnosis/troubleshooting is done at the ECM/PCM connector, use the terminal test port (A) above the terminal you need to check.

Fig 2: Identifying Terminal Test Port Of ECM/PCM Connector
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Connect one side of the patch cord's terminals (A) to a commercially available digital multimeter (B), and connect the other side of the terminals (C) to a commercially available banana jack (Pomona Electronics Tool No. 3563 or equivalent) (D).

Fig 3: Identifying Patch Chord's Terminals, Multimeter, Banana Jack And Terminals
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Gently contact the pin probe (male) at the terminal test port from the terminal side. Do not force the tips into the terminals.
NOTE:
- For accurate results, always use the pin probe (male).
- To prevent damage to the connector terminals, do not insert test equipment probes, paper clips, or other substitutes. Damaged terminals cause a poor connection and an incorrect measurement.
- Do not puncture the insulation on a wire. Punctures can cause poor or intermittent electrical connections.