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ECM 1 blows immediately after key is turned over

Tiny
ROBBIEMORRIS44
  • MEMBER
  • 1989 CHEVROLET S-10
  • 4.3L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 400,000 MILES
Any suggestions? It happened all of a sudden, only thing done differently was running a 450 watt power inverter to charge my drill batteries.
Wednesday, January 9th, 2019 AT 5:35 AM

11 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good morning,

Where are getting power from for the inverter?

I would start by disconnecting the fuel pump at the pump and see if the fuse still blows. that is the most common issue for this fuse failing.

https://www.2carpros.com/articles/how-to-check-wiring

Roy
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Wednesday, January 9th, 2019 AT 5:54 AM
Tiny
ROBBIEMORRIS44
  • MEMBER
  • 13 POSTS
I replaced the pump about six months ago. All the grounds and everything clean well before replacing. Could I disconnect the relay on the firewall? Thank you for your time.
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Wednesday, January 9th, 2019 AT 6:37 AM
Tiny
ROBBIEMORRIS44
  • MEMBER
  • 13 POSTS
I was using the cigarette lighter. New battery, starter, fuel pump, and alternator. When I got the truck it has a 40 amp inline fuse from the alternator to the battery? Not factory and not sure why it's there.
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Wednesday, January 9th, 2019 AT 6:44 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
What does the fuse feed? That does not make sense since alternator output is much greater than 40 amps.

Also, get out of the lighter and run a new line from the fuse box directly that has nothing else in the circuit.

Roy

Yes to the relay and see if it still blows.

Roy
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Wednesday, January 9th, 2019 AT 6:53 AM
Tiny
ROBBIEMORRIS44
  • MEMBER
  • 13 POSTS
Roy, I have unplugged everything, but the knock sensor on passenger side and still blows it.
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Wednesday, January 9th, 2019 AT 9:03 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
What about the ECM? That fuse also feeds power to the ECM.

Roy
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Wednesday, January 9th, 2019 AT 9:04 AM
Tiny
ROBBIEMORRIS44
  • MEMBER
  • 13 POSTS
ECM? The fuse that's blowing is ECM 1.
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Wednesday, January 9th, 2019 AT 9:06 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Yes, that is the engine control module

it has a couple of feeds and that is one of them.

It is behind the glove box. You access it from under the dash and it pulls down.

Roy

Roy
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Wednesday, January 9th, 2019 AT 9:13 AM
Tiny
ROBBIEMORRIS44
  • MEMBER
  • 13 POSTS
Okay, everything is unplugged and it's still blowing them. Could it be the ignition switch?
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Wednesday, January 9th, 2019 AT 9:48 AM
Tiny
ROBBIEMORRIS44
  • MEMBER
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Thank you for your help sir.
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Wednesday, January 9th, 2019 AT 9:52 AM
Tiny
ASEMASTER6371
  • MECHANIC
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I doubt it but it definitely is a wiring harness issue.

you need to look at the harness especially under the hood. look around anything hot.

https://www.2carpros.com/articles/how-to-check-wiring

Roy
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Wednesday, January 9th, 2019 AT 10:22 AM

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