No power to the coil packs

Tiny
ADAM TOWNSEND
  • MEMBER
  • 2003 CHEVROLET SUBURBAN
  • 5.7L
  • V8
  • 4WD
  • AUTOMATIC
  • 257,000 MILES
I've changed crank shaft sensor as well as the cam shaft sensor and tested all the fuse and computer with the test light
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Thursday, September 9th, 2021 AT 6:24 PM

4 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

I need to confirm the engine size. The 5.7L wasn't offered on this vehicle in 2003, only the 5.3L and the 4.8L. Please confirm that for me so I know which schematics to review.

Now, in general, this is really not a difficult system. Power is supplied at each coil via a fuse when the key is in the start or run position. To complete the circuit and actuate the coil pack, the PCM provides a ground path at a specific time. So, if we are not getting power at all to the coils (usually a pink wire on each connector at coils) and the fuse which supplies the power is good and has power both to it and from it, there has to be an open in the power supply.

Let me know which engine you have so I can take a look through schematics and provide the correct info to you.

One last thought. If you are getting power to the coils but no spark, there is a common issue with a common ground for all coil packs, so let me know that as well.

Take care,

Joe
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Thursday, September 9th, 2021 AT 7:23 PM
Tiny
ADAM TOWNSEND
  • MEMBER
Okay, cool. I'm sorry it's 5.3 and I have used the test light with the wiring harness with the key forward and the ground wire is grounded but there is no power coming from the wiring harness with the test light and no spark from the spark plug wires with the attempt to start and won't turn over?
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Thursday, September 9th, 2021 AT 7:31 PM
Tiny
ADAM TOWNSEND
  • MEMBER
Also I've used a diagnostic test and there's no codes coming up!
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Thursday, September 9th, 2021 AT 7:48 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

Do me a favor. If each black wire on each coil pack connector has continuity to ground, then I need you to specifically check the pink wire for power. Each coil will have a pink wire. So, once you turn the key to the on position, they all should have power.

If there is power to all pink wires (use a test light) and you have uninterrupted continuity to ground, then we need to check the connector at the PCM.

I attached the entire wiring schematic below. I highlighted all wiring related to the coils (at least I hope I didn't miss any). Take a look at them and you'll be able to identify how it works. Without seeing the schematic, it's rough.

If you again find there is no power to the pink wires at each coil, reconfirm the fuses inj1 and inj2 in the under hood fuse box are good. Also, make sure they have power to them and from them. Here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Let me know what you find.

Joe

See pics below.

Note: The schematic is 5 pages long. I had to cut each page in half to make them readable for you. I did overlap them so you can follow from one to the next. Again, the highlighted wires are related to the coils. The last pic shows the fuses I need to be checked.
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Thursday, September 9th, 2021 AT 8:49 PM

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