How to Troubleshoot Circuits at the ECM/PCM Connectors

NOTE: The ECM/PCM overwrites data and monitors the EVAP system for about 30 minutes after the ignition switch is turned to ACC (I) or LOCK (0). Jumping the, SCS line after turning the ignition switch to ACC (I) or LOCK (0) 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
Courtesy of AMERICAN HONDA MOTOR CO., INC.
When diagnosis/troubleshooting is done at an ECM/PCM connector, use the terminal test port (A) above the terminal you need to check.

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

Fig 3: Connecting Patch Cord Terminals To Commercially Available Digital Multimeter
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Gently contact the pin probe (male) at the 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 as they can damage the terminals. 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.