What would cause my 12v pink power wire running to my icm and ignition coil to be powerless?

Tiny
BUBBY46.DA
  • MEMBER
  • 1996 CHEVROLET S-10
  • 147 MILES
Hi I have a 1996 chevy s10 truck/ with a 4.3l v6 vortec. A few months ago the batterey, the alternator, and the fuel pump were all replaced to succesfully get the truck running. Witch it did for a short time. The truck ran great with no issues for a few days. One night we started it to show a friend, the next morning the truck was dead. We tried and tried to get it started but no matter what we tried it would not start. So we moved on to doing some basic diagnostics and came to the conclusion that we did not have any spark or fuel. So we proceeded to replace the ignition coil, ignition control module, crankshaft sensor, and the distributor cap. And still we have nothing. No spark and no fuel. So I got a little more in depth in testing and proceded to test the pink 12v power wire leading to the ignition module and ignition coild neither have any power going to when key is on position and when cranking engine.I am at a loss please help me diagnos this problem so that I can proced to fix it thanks. My name is drew.
Thursday, October 4th, 2012 AT 8:44 PM

10 Replies

Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
Hi Drew, I would check the the ECM/IGN fuse # 10 (20 A) in instrument panel fuse block for power. Here is a guide to help. If it does not have power I would test the ignition switch because it sounds like it went bad. Here are the ignition system and engine wiring diagrams so you can see how the system works.

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

Check out the diagrams (Below). Please let us know what happens.
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Thursday, October 4th, 2012 AT 9:06 PM
Tiny
BUBBY46.DA
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I checked all fuses in fuse pannel and all is well, where is my Ecm located at and what is the function of this part? Thank you
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Thursday, October 4th, 2012 AT 9:29 PM
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
ECM is the engine computer, the brain of the engine operating system.

I gather you have used a meter to test the fuse. What you need to test next would be the power supply to the fuse (# 10) with ignition switch turned. Both ends of fuse must have battery voltage.
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Thursday, October 4th, 2012 AT 10:12 PM
Tiny
BUBBY46.DA
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Ok I will do so thanks, also is there a way that I could possibilly check to see if truely is my ecm? I was informed by a rep at autozone that there is a way to check if my ecm is working correctly or not please verifiy. If there is such a way how would I go about doing it thank you.
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Thursday, October 4th, 2012 AT 10:19 PM
Tiny
BUBBY46.DA
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I checked the powere supply to the fuse with ignition switch on and it checked out.
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Thursday, October 4th, 2012 AT 10:21 PM
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
If you have battery voltage at the fuse, it would mean there is a break in the wire circuit between the fuse and the ICM, etc.
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Thursday, October 4th, 2012 AT 10:29 PM
Tiny
BUBBY46.DA
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Thanks for the diagrams for the wiring because I found out is was the igitions witch that was bag once I replaced it everything started working. I love this site.
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Thursday, October 4th, 2012 AT 10:35 PM
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
Glad you could get it fixed, that kind of problem can be tough. Please use 2CarPros anytime we are here to help
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Thursday, October 4th, 2012 AT 11:20 PM
Tiny
MSWITHROW76
  • MEMBER
  • 1 POST
  • 1994 CHEVROLET S-10
  • 300,000 MILES
I have a 1994 Chevy S10 with a V6 Vortec 4.3. It is not a fuel injected motor. I am having spark issues. I tested to see if power was going to and coming out of the coil and there was only 0.12 volts going into the coil and no volts going to the ignition control module. Any idea?
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Tuesday, December 4th, 2018 AT 1:41 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
You suppose to have battery voltage at the coil positive terminal that voltage is too low-check wiring back to the ignition switch-start here
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Tuesday, December 4th, 2018 AT 1:42 PM (Merged)

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