2014 Chevy Cruze ltz 1.4 turbo Crank no start with exhaust cam sensor plugged in

2014 Chevy Cruze 1.4 turbo 

Crank no start with exhaust cam sensor plugged in but starts with it unplugged.... But wait there's more 5 volts on reference AND signal wire with it unplugged..... Beating my head in on this one I unplugged every sensor I could reach and still 5 volts on both wires even cleaned and checked grounds by headlight next to pcm still 5 volts...... Rechecking some things on Mitchell right now but I am real close to calling a pcm. Not sure about fans being 5 volts pwm or not so looking that up. I did check wiring integrity and wires are not shorted to one another as I took the whole harness apart today. 

So things I will be checking tonight in wiring diagrams are 
1 anything that has a 5 volt ref going to it that goes to pcm for a signal2 any grounds I missed for pcm3 fan control 5 volt or not....
4 witches, pixies, fairies and leprechauns hiding doing magical things
Oh and fyi this is a rebuilt titled vehicle and has had a engine put in that is overheating as well ( guess they missed a thermostat to replace lol or this engine was bad from the salvage yard lol)

Also cam sensor is working like it should unless I missed something which could be the case. Any ideas welcome


Alex

The weird part is with that sensor unplugged I still have 5 volts on signal wire for exhaust cam and intake cam sensor signal wire with them unplugged after engine is started I can plug it back in and it will stay running and it also has a good waveform which is the puzzling part

I'll have to recheck but with engine running I get a good waveform 0-5 volt square wave

ok facepalm missed one crucial tid bit apparently the signal circuit has 4.8-5 volts key on engine off so with sensor unplugged that would/should be there. putting my dunce cap on now going to sit in the corner.... helps to read on a laptop than a phone.... so yeah bad cam sensor...

Why do you think the sensor is bad when it generates a good signal after being plugged in after you start the engine? Does it also generate a valid signal when
it stays plugged in during the crank/no start event? If so, you may want to look at cam timing...

Pierce or backprobe the 5 volt reference wire with the sensor plugged in. If you have 5 volts it’s not pulling the voltage down. 2nd the reluctor ring could of slipped on the cam itself

Hey juergen,

I was half awake with the last response so yes that is a valid point and I will check that out.

Very true Cheryl

code was a p0365 so I will look into that as a precaution.

Can I ask what your crank sensor is doing when the cam is plugged in? They generally run on the same reference ckt. Does the pcm see it cranking, should be able to see either the tach or on a scan tool.

Pcm sees it cranking, good wave form, ckp counts increment. Circuits are separated entirely all the way back to pcm.

As you now know, this is a normal signal bias voltage with the sensors unplugged.
Now on to the problem, it is a no start unless the exhaust cam is unplugged. What codes did you have before you started unplugging and testing sensors?
When I have seen a problem like this, it was a correlation problem with the cam/crank sensors. As in jumped timing belt/chain or as Cheryl said, a slipped tone ring. I would think you would have had some correlation codes but maybe not.

Here are the codes it had before I checked anything.

Engine
P0137 | HO2S Circuit Low Voltage Sensor 2 (Symptom 00) - Test Failed Since DTC Clear, Test Not Passed Since Power Up.
P015B | HO2S Delayed Response Rich To Lean Sensor 2 (Symptom 00) - Test Failed Since DTC Clear, History DTC, Test Not Passed Since Power Up.
P0299 | Engine Under Boost (Symptom 00) - Test Failed Since DTC Clear, History DTC, Test Not Passed Since Power Up.
P0365 | Exhaust Camshaft Position Sensor Circuit (Symptom 00) - Current DTC, Test Not Passed Since DTC Cleared, Test Failed Since DTC Clear, History DTC, Test Not Passed Since Power Up, Warning Indicator Requested.

Airbag
B1325 | Control Module Power Circuit Voltage Below Threshold (Symptom 03) - History DTC.
U0184 | Lost Communication With Radio (Symptom 00) - History DTC, Test Not Passed Since Power Up.

Body Control Module
B1517 | Battery Voltage Voltage Below Threshold (Symptom 03) - Test Failed Since DTC Clear, History DTC, Test Not Passed Since Power Up.
B3883 | License Plate Lamp Circuit Short To Battery (Symptom 01) - Test Failed Since DTC Clear, History DTC.
B3883 | License Plate Lamp Circuit Short To Ground (Symptom 02) - Test Failed Since DTC Clear, History DTC.
B3883 | License Plate Lamp Circuit Open Circuit (Symptom 04) - Test Failed Since DTC Clear, History DTC.
C0755 | Right Front Tire Pressure Sensor Too Few Pulses (Symptom 29) - Current DTC, Test Failed Since DTC Clear, History DTC, Test Not Passed Since Power Up, Current DTC Since Power Up.
U0168 | Lost Communication With Keyless Entry Control Module (Symptom 00) - Test Failed Since DTC Clear, History DTC, Test Not Passed Since Power Up.

Keyless Entry
B3120 | Keyless Entry Antenna 2 Short To Battery Or Open (Symptom 05) - Current DTC, Test Not Passed Since DTC Cleared, Test Failed Since DTC Clear, History DTC, Test Not Passed Since Power Up.

Tire Pressure Monitor
B1517 | Battery Voltage Voltage Below Threshold (Symptom 03) - Test Failed Since DTC Clear, History DTC.
B3883 | License Plate Lamp Circuit Short To Battery (Symptom 01) - Test Failed Since DTC Clear, History DTC.
B3883 | License Plate Lamp Circuit Short To Ground (Symptom 02) - Test Failed Since DTC Clear, History DTC.
B3883 | License Plate Lamp Circuit Open Circuit (Symptom 04) - Test Failed Since DTC Clear, History DTC.
C0755 | Right Front Tire Pressure Sensor Too Few Pulses (Symptom 29) - Current DTC, Test Failed Since DTC Clear, History DTC, Test Not Passed Since Power Up, Current DTC Since Power Up.
U0168 | Lost Communication With Keyless Entry Control Module (Symptom 00) - Test Failed Since DTC Clear, History DTC, Test Not Passed Since Power Up.

As you can see no correlation codes etc even though it has a laundry list of issues though most were from owner trying to figure out what was preventing the car from starting.

current reviewing waveforms as I took quite a few so hopefully I find something will post a pic in the morning.

If it were me I’d still find a known good cam crank relationship on iatn check anyway to rule it out for good. Will the sensor bolt on from intake to exhaust? Maybe try swapping them?

wrote:

If it were me I’d still find a known good cam crank relationship on iatn check anyway to rule it out for good. Will the sensor bolt on from intake to exhaust? Maybe try swapping them?

agree 100%

When you clear codes, does it continue to set the exhaust cam sensor fault?

Alrighty then after going through 20 plus waveform files I caught it messing up once

What’s it look like when it messes up? Drop out? Stuck high?

Sticks high and low tried posting a pic but keeps bringing up mimi file error it's a jpg file

Make sure your not dropping the 5 volts or ground. Use 3 channels on the scope or just 2. One hooked to 5 volt ref and ground and other to signal

Hardtopdr2, the whole mimi error has been cropping up recently. I've found that using PNG instead of JPG gets around it. Sorry for the hassle.