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Gary
Gary, Chevy Technician
Category: Chevy
Satisfied Customers: 16870
Experience:  15 years GM master tech
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Chevrolet Silverado 1500: My 08 Silverado is throwing whole

Customer Question

My 08 Silverado is throwing whole bunch of codes the truck starts up fine and then dies within a few minutes it wont start right away but when I let it sit it will start back up but then it just dies out like its starving for fuel I've checked all the grounds the pump primes fine all the connections are there I'm trying to figure out whether it's the ECM or the fuel pump control module the codes are p0122 p0171 P0174 p0223 p0506 p069e p0231p023f p0606 p064a p1255 p2635
Submitted: 2 years ago.
Category: Chevy
Expert:  Gary replied 2 years ago.
Welcome! My name is ***** ***** I will do my best to assist you with this problem.Ask me about added features such as phone contact anytime if you wish !
if you clear the codes which codes come back first ?
what has been done so far to correct this issue ?
did this problem just come out of the blue one day ?
Customer: replied 2 years ago.
I cleared the codes they came right back checked the connections grounds everything like that everything seems to be connected find all the grounds are fine I haven't changed any parts yet because I don't want to be putting 200 to 300 dollars for a new control module or new ECM in my truck if that's not the problem and it just started yesterday out of the blue
Expert:  Gary replied 2 years ago.
that is a lot of codes and for them all to come right back is very odd
you have 1/2 of the codes stating a FPCM failure and the other 1/2 are throttle control codes which a FPCM would not cause and vice versa
the only place they are related is at the PCM itself
when this truck will not start up can you see if at the FPCM if the red/white and the pink show 12 volts with the key ON ? and the solid black at the FPCM is a good ground ?
Customer: replied 2 years ago.
do I have to disconnect the harness from the control module in order to do that
Expert:  Gary replied 2 years ago.
yes
if those 3 wires check out can you see when cranking it over when it will not start if the dark green / white wire shows a good ground when cranking it over ? or volts when cranking it over ?
Customer: replied 2 years ago.
just to clarify the truck does start up but then after a few seconds or so to a minute of running it shuts off and then I have to wait a minute and then it will start back up
Customer: replied 2 years ago.
but it never run for more than a minute or two
Expert:  Gary replied 2 years ago.
when this truck shuts off and you have to wait a minute or two is there any fuel pressure ?
the problem we have if with those codes for the FPCM being set the FPCM needs to be replaced but that doesn't solve those throttle control codes being set and for those codes all to set at once really steers this issue being a PCM failure
i would like to try to capture when its acting up what that green/white wire is reading for volts when it will not run when cranking it over at the PPCM
that will steer up to the PCM or the FPCM as the next step to replace and reprogram
its very rare to have 2 modules fail like this
Customer: replied 2 years ago.
No fuel pressure according to my basic scanner it just cranks and cranks and when I let it sit for a minute then it turnes back on
Expert:  Gary replied 2 years ago.
can you see what that green/white wire reads for volts at the FPCM when no fuel pressure ?
Customer: replied 2 years ago.
I'm still going to get a bolt tester but what Dthrottle problems be cause by loose connection
Customer: replied 2 years ago.
would the throttle codes because by a loose connector to the throttle body cuz I just pushed the throttle wiring in and it connected fully
Expert:  Gary replied 2 years ago.
usually with those throttle codes either the charging system is low or most common the connection at the throttle body or the gas pedal is a bad connection and usually unplugging both connectors and packing both connectors with dielectric grease then reconnecting both connectors will correct those codes
when this will not start and the green/white wire shows close to 12 volts at it then the FPCM needs to be replaced and the new one MUST be programmed with a scan tool using your trucks VIN number for it to operate correctly as it is a module and needs programming installed in the new module for it to work
Customer: replied 2 years ago.
okay so after hooking up with us there too both the large and the small green and white wires there are 0 volts going to the tester I tried them both ways with the wiring harness ounplugged from the fpcm
Expert:  Gary replied 2 years ago.
there should only be one darkgreen/white wire at the FPCM
that should show 12 volts when cranking it over
Customer: replied 2 years ago.
im partially color blind it looks to me like there's two green and white wires one small one on the interior and one large one on the exterior corner of the part that plugs inI texted both of them and neither one of them are giving me anything and my tester does work
Expert:  Gary replied 2 years ago.
ok when this will not start up and NO green wire at the FPCM is showing any volts when cranking over the PCM would have to be bad
Customer: replied 2 years ago.
question if there aren't any volts at that wire wouldn't it just not start at all cuz it does start like I said and then it just shuts itself off
Expert:  Gary replied 2 years ago.
if no volts at that wire it the FPCM has no signal to run and should not run the fuel pump so no it should run at all
Customer: replied 2 years ago.
I get very mean 5 + volts at the red and white wire nothing at the rest of them but it does start
Customer: replied 2 years ago.
I don't get it
Expert:  Gary replied 2 years ago.
thats really odd
the pink and the red/white should show 12 volts with the key ON and cranking it over
Customer: replied 2 years ago.
I know and I check the tester with the battery and it shows full power on the battery
Customer: replied 2 years ago.
okay I'm getting 11 volts when I go to the red wire and the ground wire but nothing anywhere else the ground I was using was bad on the frame but its at 11 volts with that red wire and then me using the ground as the I believe the black wire
Expert:  Gary replied 2 years ago.
the pink shows NO volts cranking it over ?
Customer: replied 2 years ago.
correct only when I touch the red and the black wires none of the other wires show any volds
Expert:  Gary replied 2 years ago.
lets see if another expert has any ideas
hang on another expert will replay back to you
Customer: replied 2 years ago.
Ok
Customer: replied 2 years ago.
Any ideas
Customer: replied 2 years ago.
?