2004 GMC Yukon Denali 6.0 crank no start

[Frankie1074]

I have a 2004 GMC Yukon Denali 6.0 with crank no start with codes P0335 and P0342, while checking the crank sensor I notice that I'm not getting
the 12 volt reference from the PCM, check the wiring for shorts found none, unplug the C1 connector and put 12 volts battery voltage from the battery + terminal thru a fuse and I get 12 volts, try different PCM and have the same issue, the only way I can start the Yukon is running 12 volts thru the battery but it has a long crank before starting and the only code remaining is P0342, this happen after the shop change the engine, also check all the powers and grounds on the PCM all are good, it's not my shop but I'm helping this shop finding the issue, any suggestions on what else can be the issue.

P.S. One thing I notice is that the anti-theft light come with the KOEO after about a minute of been off, I don't know if this has anything to do with it or
not, I'm still checking on that.

 

[Fless]

The Cam signal is not required for the engine to run, but not having it can cause a long crank time. (A CASE relearn can correct this if both cam and crank sensors are online.)

If the PCM is generating 12v on C1 pin 2, but there's no corresponding voltage at the crank sensor harness, there may be a compromised wire. Instead of supplying voltage from the battery for the Lt Grn wire, can you bypass it with an overlay for a test? Or is that what you effectively did?

If so, have all of the PCM & IGN fuses been verified as good in the fuseboxes? Fuse legs good, with good pin tension?

It could also be that the 12v from the PCM is being pulled down by another sensor circuit (many times the 12v supply in the PCM feeds several sensors), so unplugging the cam sensor -- if that's what's causing it -- might let it start (maybe with a long crank or second try). I don't know which other sensors would be supplied 12v by the PCM; perhaps better diagnostic info would tell.

Engine Controls Diagram 7 — 2004 GMC Yukon/Denali 2WD V8-6.0L VIN U Service Manual | Operation CHARM

Detailed repair manual for the 2004 GMC Yukon/Denali 2WD V8-6.0L VIN U.

charm.li

 

[Fless]

I have a 2004 GMC Yukon Denali 6.0 with crank no start with codes P0335 and P0342, while checking the crank sensor I notice that I'm not getting
the 12 volt reference from the PCM, check the wiring for shorts found none, unplug the C1 connector and put 12 volts battery voltage from the battery + terminal thru a fuse and I get 12 volts, try different PCM and have the same issue, the only way I can start the Yukon is running 12 volts thru the battery but it has a long crank before starting and the only code remaining is P0342, this happen after the shop change the engine, also check all the powers and grounds on the PCM all are good, it's not my shop but I'm helping this shop finding the issue, any suggestions on what else can be the issue.

P.S. One thing I notice is that the anti-theft light come with the KOEO after about a minute of been off, I don't know if this has anything to do with it or
not, I'm still checking on that.

Any update on this?

 

[rockola1971]

Typically when the anti theft is actively trying to keep you from stealing your own vehicle the light will flash. Our generation of PASSLOCK anti theft does NOT keep the engine from cranking. It allows the engine to crank and then start and run 5-10 seconds before fuel pump is cutoff. Id go ahead verify you have fuel pressure during engine crank. This is very likely electrical related. Has this vehicle had this problem since you got it back from engine installer? How did you get vehicle home? Are you sure you have the right generation 6.0 installed?

What on earth does this mean? "the only way I can start the Yukon is running 12 volts thru the battery"