HELP - Only Starts with Camshaft Sensor Disconnected

[Geotrash]

See the link below and scroll down to the second diagram (Engine Data Sensors - 5-volt and Low Reference). Dead center is the Camshaft Position sensor and it shows the wire colors for the 5v Ref #1 (D-BU) and the ground (BN). That 5V Ref is shared by a few sensors on the left side of the diagram, but from different ECM pins.

Electrical Diagrams — 2007 Chevrolet Suburban 4WD V8-5.3L Service Manual | Operation CHARM

Detailed repair manual for the 2007 Chevrolet Suburban 4WD V8-5.3L.

charm.li

Thank you, Steve. You saved me from digging.

 

[evanw0920]

See the link below and scroll down to the second diagram (Engine Data Sensors - 5-volt and Low Reference). Dead center is the Camshaft Position sensor and it shows the wire colors for the 5v Ref #1 (D-BU) and the ground (BN). That 5V Ref is shared by a few sensors on the left side of the diagram, but from different ECM pins.

Electrical Diagrams — 2007 Chevrolet Suburban 4WD V8-5.3L Service Manual | Operation CHARM

Detailed repair manual for the 2007 Chevrolet Suburban 4WD V8-5.3L.

charm.li

Thanks, will try this out and get back to y'all.

 

[Fless]

Thanks, will try this out and get back to y'all.

I hope it helps. Seems like a short or lost ground on a circuit like that would set some kind of code.

 

[evanw0920]

I hope it helps. Seems like a short or lost ground on a circuit like that would set some kind of code.

Hey guys, finally got the new sensors in to no avail. I did test the wires and there was 5v. Still just cranks but doesn't start unless I unplug the sensor. Still no codes either.

Is the only other possibility an issue with the ECU?

I did check the timing chain and it hasn't jumped timing.

 

[evanw0920]

A couple of updates.


We have replaced the ECU, as another issue came up with the throttle body, which the new ECU did fix. Sadly, it did not fix the no-start unless cam sensor is unplugged issue.

Still just a crank, no-start condition.

Still not getting any codes

Is there anything specific that we should check or recheck, to hopefully fix this issue?

Thanks in advance.

 

[Fless]

Has a successful CASE relearn been done with the new ECU?

 

[evanw0920]

Has a successful CASE relearn been done with the new ECU?

Yes, it has.

 

[evanw0920]

Hello everyone, just a couple more useful updates.

We replaced the Fuel Pump - originally replaced it in 2023 but replaced it again as it was under warranty and we wanted to see what happened.

After replacing the fuel pump, it actually started multiple times with the sensor plugged in, but then it stopped working again with it plugged in ??

 

[evanw0920]

Zero Compression on Cylinder 3 as well.