Help LQ4 camshaft position sensor code p0343
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Help LQ4 camshaft position sensor code p0343 My ls swap truck had went into water motor had water flushed it all out removed heads cleaned it put all back together bought new wire harness new computer new crank and cam sensor cam plug is getting 12v when motor is on but takes forever to turn on and back fires when it’s plugged in but when unplugged it turns on quick I don’t know what els to do I’m thinking it’s cam but I’m not sure
If you bought non-OEM sensors, not kidding I'd bet there's a full 30% chance it's bad out of the box. Something's going on with quality of these parts post-covid, as cheap as I am I still go for the OEM because of what I've seen.
But I think that code is "signal high" on the cam sensor, Id throw a scope on the signal lead at the PCM and see what's what. I'd try to use the PCM's ground to see the signal as the PCM does. Should be a nice long squarewave that switches once every crank 360 if i recall correctly. It only tells the computer which of the two strokes it's on. Could be bad ground or wire shorted or...?
Actually, that signal is so long and unpronounced you could probably use a voltmeter to troubleshoot while turning the engine by hand. Should be high for 360 degrees of crank then low for 360 degrees of crank.
But I think that code is "signal high" on the cam sensor, Id throw a scope on the signal lead at the PCM and see what's what. I'd try to use the PCM's ground to see the signal as the PCM does. Should be a nice long squarewave that switches once every crank 360 if i recall correctly. It only tells the computer which of the two strokes it's on. Could be bad ground or wire shorted or...?
Actually, that signal is so long and unpronounced you could probably use a voltmeter to troubleshoot while turning the engine by hand. Should be high for 360 degrees of crank then low for 360 degrees of crank.
Last edited by mk3cn4; Sep 26, 2023 at 09:38 PM.
