Can this be?

[BWGuy]

OK. I thought I was pretty sure I could tell if a crank sensor was working or not, but now I'm not sure.

So, my Brother in Law's vehicle quits, cranks but won't start, and we check for spark on a couple of plugs&coils and nothing.

Checked the relevant fuses and such, and they're all good.

Plugged in a PC that can talk to ECM, and while cranking, I get a good RPM value of around 220 revs on my computer (from the ECM), so I figure the crank sensor must be working. JUST TO BE SURE, though, I disconnect the crank sensor and crank the engine again and verify the RPM shows "0". Then plug it back in and crank some more and we've got RPM at 220 or so again.

Long story short, I check a bunch of other stuff and then come to the best guess that the timing belt may have slipped, 'cause the internet says if the cam sensor signal doesn't agree well enough with the other cam sensor and/or crank sensor, then the ECM refuses to send ignition signal to the igniters.

Since a local shop had changed his timing belt about a month ago and the work was still under warranty, I told Brother in Law to take it back to them, which he does.

Bing bang boom, they say the problem was the crank sensor, so they charge him $270 for tow, diagnosis, and part n labor for sensor.

So, is this possible? Can a crank sensor be sending a good enough signal to the ECM that it can convert to believable RPM value, but still be bad enough that it would prevent spark?

[fishsticks]

Totally possible.

220 seems low for cranking RPM, but in truth I've never measured.