Written: June - July, 2023

Diagnosing a "crank/no-start"

• First of all, will it crank? If not, that is another game entirely.
• Turn key to on, watch if "service engine" icon lights up at least briefly.
• Turn key to on, listen for fuel pump to run for 1 second (KOEO prime).
• Crank vehicle and watch tachometer.
• Basic principles - do we have both fuel and spark?

Note: the 1 second fuel pump run thing is called KOEO prime (Key on, Engine off). There is often "schrader valve" to check for fuel delivery (along with a place to hook up a fuel pressure meter). KOER by the way is "key on, engine running".

More lingo. PCM versus ECM. An ECM is an engine control module. A PCM is a "powertrain control module" and is basically and ECM with functionality to control the transmission added.

Note that the crankshaft position sensor may be ignored during cranking (starting the engine). This would explain on my Tacoma why the tachometer reads 0 RPM during cranking. It would seem that the tachometer is a display driven entirely by the ECM and does not display raw RPM information.

The following 90 minute video by Mr. Schrodinger is much better than his timing belt videos that I gave links to above. He avoid blowing off steam and venting on his watchers and gives a nice display of clear thinking and deductive troubleshooting.

• Honda Civic, cranks, no start