P0481 code on 2000 trans am
Thread Starter
Teching In
Joined: Aug 2022
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P0481 code on 2000 trans am Hey everyone, I've looked at the variety of threads here about p0481 and tried all the solutions people said and still couldn't come up with anything...
ive bench tested the Rad fans,
both fans come on low when driving as they are supposed to.
After driving for a bit eventually 481 comes up. I've tried swapping relays from position to position and test lighted and multi metered at that C100 connection
I thought it was the blue wire under relay 2 possibly with a **** connection, so I ran a new wire and code still comes up.
I'm not very good with electrical, but on connection J(dark green) I think on c100 connector going to the relay side I get 12v. I got nothing on the blue one. Which is the one I cut and ran a new wire as I had read that was supposed to show 12v.
I'm pulling whats left of my hair out. I testsd the relays and they seem to be doing what they are supposed to so my only thought is something is shorting out. I don't believe it's pcm related but i had a hard time understanding the testing side of the c100 to the pcm from what I read.
I am about to consider just running a manual fan switch and see about putting in the diodes or whatever to make the code not show.
Any insight would be greatly appreciated.
ive bench tested the Rad fans,
both fans come on low when driving as they are supposed to.
After driving for a bit eventually 481 comes up. I've tried swapping relays from position to position and test lighted and multi metered at that C100 connection
I thought it was the blue wire under relay 2 possibly with a **** connection, so I ran a new wire and code still comes up.
I'm not very good with electrical, but on connection J(dark green) I think on c100 connector going to the relay side I get 12v. I got nothing on the blue one. Which is the one I cut and ran a new wire as I had read that was supposed to show 12v.
I'm pulling whats left of my hair out. I testsd the relays and they seem to be doing what they are supposed to so my only thought is something is shorting out. I don't believe it's pcm related but i had a hard time understanding the testing side of the c100 to the pcm from what I read.
I am about to consider just running a manual fan switch and see about putting in the diodes or whatever to make the code not show.
Any insight would be greatly appreciated.
Thread Starter
Teching In
Joined: Aug 2022
Posts: 5
Likes: 1
Remember the pcm gives the ground to close the relay contacts. Check the cooling fan3 relay. It must have 5 connectors on it not 4. Diagram
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From: Dade City, Fl.
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Thread Starter
Teching In
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Will update once I recieved and installed.
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Teching In
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So update to anyone curious. I believe it was just the blue wire running from relay 2 to the c100 pack on the passenger side I just cut it and ran a new wire, at some point I'll try to pull the old one out. But everything is functioning properly. I also replaced all 3 relays just in case. So hopefully it helps someone else!
