How to check starter and ECM wire with diagram?

Thanks Steve!
When turned the key on III position, dash boar lights all turned on. I attached video. Several days ago I could shift gear from neutral to parking, but today the gear was locked I could not move from parking position to neutral.
When turned on engine the starter crack sound is very weak, alternator moved second, and engine could not start.

When P0302 and P0303 codes appeared, I replaced spark plugs and coils. But the codes were still pop out. Then, I suspected fuel injectors may be problem, and tested their resistances with multi meter, but four injectors showed all similar resistance around 11.04 Ohm.

I did an injector circuit power test using the voltmeter negative side connected to the negative side of the battery. Key on at III position without start engine, positive end probe both sides of injector wiring connector. The voltage showed all zero on all four injector wires, indicating circuit was disconnected. So, I need to check the wires and connectors.

And I tested the engine starter, with voltmeter set 12V, connected on both battery ends, and checked voltage changes when key on starting position. There was voltage decrease from 12.7V to 10 v, indicating starter may be OK. But starter crack sound is very weak when turned key to the start position. And could not start engine.

So, I want to check the wires to starter and to ECM. I got diagrams from former your technician, but I could not identify the real parts and locations, and how to test wire, etc,
I tested fuse boxes but could not find broken fuse.
Thanks a lot for your help and instruction!

No. The Battery voltage was 13.25 v after charging freshly, but it could not start engine. Crank sound is weak on starter that couldn’t start up engine. Circuit to injectors to starter and ECM is needed check.

Yes. That’s right. I need a detailed circuit diagram with parts name on it and follow it to check circuit. May you provide detail protocol how to check circuit from better to circuit and from the circuit to ECM? And detection methods. Connection parts and in circuit. The difficulty for me is that I can read diagram, but don’t know where is parts, location, and where to check the connection. Thanks for your help!

Hi Steve!

Thanks a lot for your many precious instructions and help!
I replaced the spark plugs, coil packs, and fuel injectors, detected voltages, voltage down, resistance, and checked fuses, and all plug wires. Now no code, and with cycle relearning drive activated five inactivated functions on OBD-II auto scanner. And got through inspection and renewed registration.
The new problem now is that fuel trims lean, ST FTRM1 (%) was -0.85(%), and LT FTRM1 (%) WAS -14.0(%), and after cleared codes, there was no freeze frame stored, no freeze frame events detected.
With lean fuel trim data, car was powerless than before, and hard to increase speed from start to 40 mph, after then, it was no problem increase from 40 mph to 70 mph on the highway.

How to fix the problems practically by myself?

When I check injectors wire and looked at bases of each injectors I found #2 and #3 injector bases were not tightly inserted to the base, and the bottom of injectors very dirty covered with dirty debris and oils fixed round of injector bottom as images attached. Sb had touched the injectors. The injector leak and contamination as well as congested injectors may be the error sources. Therefore, I replaced the two problematic two injectors with OEM honda parts, OEM ignitioin coils and OEM spark plugs. Great recommendation I will check with fuel pressure.

I detected resistance on the two new injectors and two old injectors, and found all four injectors have the same resistance.

Where is fuel pressure sensor location for honda accord 2009? Is it necessary to test its function? Where to connect a fuel pressure meter?