PLEASE HELP! 1999 Yukon crank no start

JP907ATB

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Hello i am working on a friends 99’ Yukon. A few days ago it was running rough and stalling, changed the fuel filter and air filter and was running like a top. A few days later truck died after going through carwash, and am currently in a crank no start situation. I have scanned codes there are no global obd2 codes, but there are 40 codes coming up in the pcm under gmc oem enhanced. I have verified fuel pressure via manual gauge on shrader valve on fuel lines top of motor. 60psi prime and 62psi while cranking. I pulsed the injectors and saw in even 9-10psi drop on each injector. I beleive this isn’t a fuel issue because i can’t get the truck to fire at all even with a shot of either in the intake. I have tried changing the mass air flow sensor, crankshaft sensor and camshaft sensor with no change. I have pulled wiring harnesses apart and cleaned them and applied dieeltric grease to them. I cleaned up all the grounds i could find and used copper anti seize on them. And still crank and no start and 40 pcm codes that will not clear. I’m starting to wonder if the ecm/pcm shit the bed?? Other then that i am running out of ideas.
The codes are:
P0101 mass air flow sensor performance
P0106 manifold absolute pressure sensor performance
P0107 map sensor circuit low voltage
P0108 map sensor circuit high voltage
P0121 throttle position sensor circuit insufficient activity
P0125 engine coolant temp insufficient for closed loop fuel control
P0131 heated o2 sensor circuit low voltage bank 1 sensor 1
PO132 heated o2 sensor circuit high voltage bank 1 sensor 1
P0133 heated o2 sensor slow response bank 1 sensor 1
P0134 HO2S circuit insufficient activity bank 1 sensor 1
P0135 HO2S heater performance bank1 sensor 1
P0137 HO2S circuit low voltage bank 1 sensor 2
P0138 HO2S circuit high voltage bank 1 sensor 2
P0140 HO2S circuit insufficient activity bank 1 sensor 2
P0141 HO2S heater performance bank 1 sensor 2
P0151 HO2S circuit low voltage bank 2 sensor 1
P0152 HO2S circuit high voltage bank 2 sensor 1
P0153 HO2S slow response bank 2 sensor 1
P0154 HO2S corcuit insufficient activity bank 2 sensor 1
P0155 HO2S heater performance bank 2 sensor 1
P0157 HO2S circuit low voltage bank 2 sensor 2
P0158 HO2S circuit high voltage bank 2 sensor 2
P0160 HO2S circuit insufficient activity bank 2 sensor 2
P0161 HO2S heater performance bank 2 sensor 2
P0171 fuel trim system lean bank 1
P0172 fuel trim system rich bank 1
P0174 fuel trim system lean bank 2
P0175 fuel trim system rich bank 2
P0300 engine misfire detected
P0325 pcm knock sensor circuit
PO327 knock sensor low voltage
P0336 CKP sensor a circuit performance
P0337 CKP sensor circuit low duty cycle
P0338 CKP sensor circuit high duty cycle
P0339 CKP sensor circuit intermittent
P0340 camshaft position sensor circuit
P0341 CMP sensor performance
P0401 EGR flow insufficient
P0404 EGR open position performance
P0405 EGR position sensor circuit low voltage
There is also a pass lock code that comes up twice it shows the same code as current and as in the history
C0472 steering hand wheel speed sensor circuit

I am pretty stumped here and leaning towards a new ecm/pcm. I find it hard to beleive all of these sensors could fail at once. If anyone has any input i would greatly appreciate it.
 

exp500

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What are your Spark test results? Test at coil and at Distributor. Your fuel pressure is low. 62-66 at key on by the book. Ecm replacement is rare on these models. Check fuses.
Clear your codes but share the passlock code with us.
 

Joseph Garcia

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Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving sage advice from the knowledgeable folks on this Forum, and others will chime in.

As indicated above, my first guess would be an issue in the ignition system. How did the distributer cap and rotor look (assuming that your year still had them)?
 
OP
OP
J

JP907ATB

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What are your Spark test results? Test at coil and at Distributor. Your fuel pressure is low. 62-66 at key on by the book. Ecm replacement is rare on these models. Check fuses.
Clear your codes but share the passlock code with us.
Well i just pulled one plug on cylinder 1 and checked for spark while cranking, i had spark on that plug so i figured it was sending spark to others.
 

89Suburban

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Maybe the antiseize is hurting your metal to metal contacts? Did you put that on before or after assembling?
 
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JP907ATB

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Maybe the antiseize is hurting your metal to metal contacts? Did you put that on before or after assembling?
Copper anti seize will lot interfere with the ground connections. I use it on all my rigs and it also helps them keep a good ground over time keeping water and dirt out
 
OP
OP
J

JP907ATB

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Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving sage advice from the knowledgeable folks on this Forum, and others will chime in.

As indicated above, my first guess would be an issue in the ignition system. How did the distributer cap and rotor look (assuming that your year still had them)?
I pulled the plug out of cylinder 1 and looked for spark while cranking, i figured if i had spark there the other plugs would be getting spark as well
 

OR VietVet

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Yes, sounds like a spark problem and possible ecm related. If you pull all plugs I would bet the are fuel fouled and need replaced. I would check all grounds again and make sure you have clean tight metal on metal connections.

 
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J

JP907ATB

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Yes, sounds like a spark problem and possible ecm related. If you pull all plugs I would bet the are fuel fouled and need replaced. I would check all grounds again and make sure you have clean tight metal on metal connections.

Any ideas where the ecm/pcm grounds at? Also if i had spark on at least one plug wouldn’t it atleast try to fire off a little? I can’t get it to do anything even with a snort of either it just cranks for days
 

OR VietVet

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I wish I did know all the grounds locations. They go from front to back and side to side. Unless someone here has a manual for this year truck or you are on AllDatadiy.com or another knowledge source, I would have to just check it out all over the rig.

You said it died going thru a car wash and that is key. Water got in somewhere for sure.
 

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