After completing an LS swap, engine power reduce message turned on?

Tiny
FRANK GUERRA
  • MEMBER
  • 1998 CHEVROLET SILVERADO
  • 5.3L
  • V8
  • 2WD
  • AUTOMATIC
  • 12,500 MILES
I did a ls swap into my truck listed above 1500. I got it to start, then I gave it gas then I saw a message reading engine power reduce. I read that it's going to be the throttle body. So I took it off an put another on, that I had that I knew it worked. Installed it and started it up. I didn't see it. I gave it gas then it popped up again. Now let me say I do not have the full exhaust on yet. So, I only have the front 2 02 sensors, and my old connector isn't working and it was at first. I have checked the grounds, and it looks good, but I am going to double check. Thank you for taking the time to read this
Monday, August 26th, 2024 AT 10:14 PM

9 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,347 POSTS
No problem, lets run the codes to see which ones are stored that way we can go in the right direction on fixing it. This guide can help:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Can I ask if you changed the PCM and wiring harness asl well? Do you have a throttle cable or is it he newer "fly by wire" setup?

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Tuesday, August 27th, 2024 AT 10:15 AM
Tiny
FRANK GUERRA
  • MEMBER
  • 8 POSTS
The wire harness is the same. Well, the whole truck harness is the same. I have the donor truck next to the truck that I put the engine if. It is dbw, an as for as the PCM it is not the one that came with it.I.I couldn't afford to take it to get the vat off so I use a PCM off of another LS dbw engine that I had in the garage that the PCM vats was off. The engine is the same to the t. And I don't know if I mentioned it is reading battery is not charging. An I haven't ran the exhaust all the way yet. But the O2 are hook up.
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Wednesday, August 28th, 2024 AT 6:52 PM
Tiny
FRANK GUERRA
  • MEMBER
  • 8 POSTS
Sorry I forgot to say. It did throw codes probably 7 to 8. Like 101 102 I forgot what the other ones were. So I started checking a few things. Found a few wires that got cut so I cut them solder and heat shrink them. Added a couple more grounds. Then my OBD2 wasn't working. Solved that problem. Change fuse out. Today I started the truck and ran it hit the gas real fast and it went into limp mode reduce engine power. Put scanner p1518. An that was it.
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Wednesday, August 28th, 2024 AT 7:06 PM
Tiny
KEN L
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So, did you change the throttle body out for a cable style? How did you get around the fly by wire throttle body? The P1518 code is related to the throttle actuator control (TAC) module.
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Thursday, August 29th, 2024 AT 10:01 AM
Tiny
FRANK GUERRA
  • MEMBER
  • 8 POSTS
  • 1998 CHEVROLET SILVERADO
  • 5.3L
  • V8
  • 2WD
  • AUTOMATIC
  • 12,500 MILES
I have install a ls out of a 03 Chevy Silverado an put it in a 98. Now I have taken out all the wire harness from the 98 an installed the harnesses from the 03.I know I know I didn't have too but I did. Everything is hooked up an when I turn the key I have nothing but the sound of the throttle body. How should I diagnosed the problem.I have the donner truck next to me. It's been a while since I did this the last one I did I put in a Dodge Dakota.
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Thursday, August 29th, 2024 AT 10:02 AM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,347 POSTS
So, the engine does not crank over? or does it crank over but not run? Please go over this guide and report back so I can help you:

https://www.2carpros.com/articles/car-cranks-but-wont-start

Also, can I ask if the security light is flashing? Please go over this guide and get back to us.

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Thursday, August 29th, 2024 AT 10:02 AM (Merged)
Tiny
FRANK GUERRA
  • MEMBER
  • 8 POSTS
Ok I got it running now. An it's throwing a reduce engine power. But sir I have posted this problem twice on here. Sorry for that. Dont want to waste your time when someone is helping me on another post. Ty sir
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Thursday, August 29th, 2024 AT 10:02 AM (Merged)
Tiny
FRANK GUERRA
  • MEMBER
  • 8 POSTS
Okay. Update. I was using another PCM I had but I put the original one back in and it stopped the message. I thought I had to take it to get the vat off. But I found out how to take it off by just turning the key on the on position for three times for ten minutes. Qn it works. Thank you.
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Saturday, August 31st, 2024 AT 4:23 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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Glad you could get it fixed, thanks for letting us know. Please use 2CarPros anytime we are here to help.
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Saturday, August 31st, 2024 AT 4:38 PM

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