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Crank no start? CRANK NO START I HAVE 12V TO CRANK AND CAM SENSOR?

Tiny
LOUD_8.1VORTEC
  • MEMBER
  • 2003 CHEVROLET SILVERADO
  • 8.1L
  • V8
  • 4WD
  • AUTOMATIC
  • 155,000 MILES
Hello,

I have 62 PSI of fuel pressure and I have sparks and also a good compression 190 PSI the only one is that I have pulses of only 6 volts to injectors with no resistance in the wires between injectors and PCM. All truck fuses and relays are okay. The crank and cam sensor are new. The truck has worked some miles with no problem. I already changed the BCM, and I did relearn procedure for the vats (pass lock) etc. And I didn’t have any security light, but I suspect that this is because a similar problem happened to me when changing BCM more I scanned it and there is a non-communication code between BCM and i/p and PCM. But yet I managed to make it run despite this problem last fall so here it is.
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Wednesday, January 25th, 2023 AT 1:09 PM

27 Replies

Tiny
LOUD_8.1VORTEC
  • MEMBER
  • 20 POSTS
  • 2003 CHEVROLET SILVERADO
  • 8.1L
  • V8
  • 4WD
  • AUTOMATIC
  • 180,000 MILES
Okay, I have an 8.1 Vortec then it’s been one and a half years since it didn’t start because it had injectors to do, but it was starting and 6 months ago. I tried to start i, it started for like 5 seconds holding the accelerator and a rough then it turned off and week went by I tried to start it and after 20 key cycle it started rough like 3 seconds holding the accelerator then it no longer starts since jai 62 PSI of continuous fuel pressure 12v to coil piece new: spark plug, coil, spark plug wire, air filter, fuel, fuel filter. Injector. I have 12v to crank and cam sensor and to crank signal jai 5v I don’t know if it’s normal I think it’s 10v but. I need help, it has to start. I think it’s the computer that’s not sending the 5v signal to the coil because I didn’t have time to see if I’ve has spark. The only code appeared because it’s not the right BCM but yet it started super well with it suddenly no because I’m changing the interior to make it luxurious LTversion brief. Grounds are good no resistance. The only dtc code is p0711-p0722-p0732-and full of other code that makes no sense and I have:u1041u1096 yet when I installed the BCM there was no code and it started super well and it is not a problem of pass lock because it is already programmed I do not have the code in the dash I do not have the symptoms of it.
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Thursday, January 26th, 2023 AT 12:00 PM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,536 POSTS
The crank sensor gets 5 volts, and the coil gets 12 volts. Can I ask if the security light is flashing when you try to crank the engine over? If so, you can try to follow this guide to reset it:

https://www.2carpros.com/articles/how-to-reset-a-security-system

Next, we need to check for spark, this video will help:

https://youtu.be/baq_aEWNQ0Y

If it has spark, please see if the engine will run on starting fluid.

This guide can help as well:

https://www.2carpros.com/articles/car-not-running-advanced

Also, you can try a hard reboot which is done by removing the negative side of the battery, with the cable loose from the negative side of the battery, hold it to the positive terminal for 1 minute this will discharge the memory capacitors in the BCM and PCM allowing the system to reboot.

Please go over these guides and report back.
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Thursday, January 26th, 2023 AT 12:00 PM (Merged)
Tiny
LOUD_8.1VORTEC
  • MEMBER
  • 20 POSTS
That is not the pass lock security. I’ll try starting fluid and see if I have spark. Tomorrow my Noid injector tester arrive so I’ll check if I've injector pulse, but I have a question for you the Noid tester does it light on with 12v only cause I’ve seen that injector can receive only 6 volt. So don’t enough of voltage to pulse and start the vehicle if is the case what cause that low voltage the ground is solid. How to check the voltage with multimeter the voltage at injector.
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Thursday, January 26th, 2023 AT 12:00 PM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,536 POSTS
Remove the injector connector and test for 12 volts using a voltmeter.

Here is a guide that can help:

https://www.2carpros.com/articles/how-to-test-a-fuel-injector

The PCM grounds the injector it triggers the injector valve.

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Thursday, January 26th, 2023 AT 12:00 PM (Merged)
Tiny
LOUD_8.1VORTEC
  • MEMBER
  • 20 POSTS
Okay, I just wanted to be sure concerning testing injector. I checked yesterday I have spark no injector pulse 0v with ground at injector harness with the switch at on. 12v with the battery ground so no short in injector harness. And I have spark 62 PSI fuel pressure and I don’t have the pass lock light when cranking.
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Thursday, January 26th, 2023 AT 12:00 PM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,536 POSTS
The injector pulse works off off ground to you must have the test light on the power side of the battery. The power side stays on when the key is on.
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Thursday, January 26th, 2023 AT 12:00 PM (Merged)
Tiny
LOUD_8.1VORTEC
  • MEMBER
  • 20 POSTS
I have no ground crtl from the pcm but I get 12v cause if I put neg of my multimeter on neg of my battery I get 12v. I have crank cam maf signal good ground 12v no passlock security light on what it could be. In more this truck 1 1/2 years ago was running perfect and this truck is a project so he haven’t see the road in 5 years so what can it be if the sensor or good and changed the bcm about a year ago it wasn't the right one but I haven't got any code and he was running good. And 6 month ago that hell has begun crank no start no injector pulse but have 62psi fuel pressure and got spark. So how can he not start one day pow like this. I don't have a scope but I've done every this and he pass I just don't have the neg pulse to injector
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Thursday, January 26th, 2023 AT 12:00 PM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,536 POSTS
It sounds like the PCM is out, I would do a CAN scan to see what's going on and confirm the failure. You can get a CAN scanner (Controller Area Network) from Amazon for about $36.00.

Here is a video to show you how:

https://youtu.be/u-4syLc-ifQ

and

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Amazon CAN scanner link for about $35.00.

https://amzn.to/3R9lJ60

Here is how to change out the PCM in the images below. You can get a rebuilt unit by searching Google or eBay. Check out the images (below). Please let us know what happens.

Images (Click to make bigger)
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Thursday, January 26th, 2023 AT 12:00 PM (Merged)
Tiny
LOUD_8.1VORTEC
  • MEMBER
  • 20 POSTS
How can it be my PCM if my has running about 24 hours in 3 years seriously I’ve another Silverado with 350100km on it with stock PCM and it work perfectly I’m sure it’s another thing the PCM decide to not ground pulsing the injector.
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Thursday, January 26th, 2023 AT 12:00 PM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,536 POSTS
Yep, me too, does it have spark? But no injector pulse?
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+1
Thursday, January 26th, 2023 AT 12:00 PM (Merged)
Tiny
LOUD_8.1VORTEC
  • MEMBER
  • 20 POSTS
No injector pulse and no spark.
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Thursday, January 26th, 2023 AT 12:00 PM (Merged)
Tiny
LOUD_8.1VORTEC
  • MEMBER
  • 20 POSTS
12v to injector just no gnd signal from PCM without short in wires between them.
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Thursday, January 26th, 2023 AT 12:00 PM (Merged)
Tiny
LOUD_8.1VORTEC
  • MEMBER
  • 20 POSTS
No pass lock security light on.
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Thursday, January 26th, 2023 AT 12:00 PM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,536 POSTS
This means the injector drive inside the PCM is bad or you have a shorted ignition coil which is common which will shut the ignition driver down as well. I would disconnect all if the coils and test for 12 volts and a grounding trigger. Let me know please.
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-1
Thursday, January 26th, 2023 AT 12:00 PM (Merged)
Tiny
LOUD_8.1VORTEC
  • MEMBER
  • 20 POSTS
I get spark, just its the ground injector pulse I’m not getting?
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Thursday, January 26th, 2023 AT 12:00 PM (Merged)
Tiny
LOUD_8.1VORTEC
  • MEMBER
  • 20 POSTS
Can you help me think about it PCM goes bad while the truck has running like 12 hours in 3 years it’s impossible and I want a fisable solution.
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Thursday, January 26th, 2023 AT 12:01 PM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,536 POSTS
Let's try to unplug all of the injectors and ignition coils to see if you can get the PCM to come back and trigger the injectors or coils. If one of these is shorted it will cause the PCM to stop working.
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Thursday, January 26th, 2023 AT 12:01 PM (Merged)
Tiny
LOUD_8.1VORTEC
  • MEMBER
  • 20 POSTS
You’re telling me that by unplugging the injectors and coils this will get my ground pulse back on my injectors.
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Thursday, January 26th, 2023 AT 12:01 PM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,536 POSTS
It may, if the coils are shorted inside an injector or coil it will cancel out the PCM signal.
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Thursday, January 26th, 2023 AT 12:01 PM (Merged)
Tiny
LOUD_8.1VORTEC
  • MEMBER
  • 20 POSTS
Seriously, I’m getting spark but an inside coil short first how can inside of the coil without running I know an engine sitting for a while can wear a bit but not much like this and can you put another mechanic in this case because it has been two weeks of searching and no solution.
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Thursday, January 26th, 2023 AT 12:01 PM (Merged)

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