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Discussion Starter #1
I currently have a gen 3 LQ4, and am thinking about switching over to a gen4 58x engine. I have a holley dominator and the LS1 specific holley engine harness. Is there any way to modify my harness to work with a 58x engine? Is it as simple as extending the cam sensor wires up front and swapping the pigtail for the crank sensor? Are the 58x and 24x crank sensors wired the same but just have a different output? I'd prefer to modify my harness vs buying a new LS2/3 harness if possible.

Thanks!
 

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Look at the differences in the wiring diagrams on your software.

If I recall, it's not a simple "extend the wires and install a new plug end the same as the 24x one". Something about one system uses 12v and the other is 5v. I don't remember exactly.
 

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As said, the factory 58x crank and cam sensors run off the 5v ref wire and the Holley 58x harness is wired accordingly. Some sensors that are designed for 5v can be damaged at higher voltages. If it was me I'd power these with 5v. I know others use 12v however on 58x applications, maybe some others can comment.

Other than that extend the cam and swap crank pigtail. Knock sensors are completely different.
 

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Discussion Starter #4
As said, the factory 58x crank and cam sensors run off the 5v ref wire and the Holley 58x harness is wired accordingly. Some sensors that are designed for 5v can be damaged at higher voltages. If it was me I'd power these with 5v. I know others use 12v however on 58x applications, maybe some others can comment.

Other than that extend the cam and swap crank pigtail. Knock sensors are completely different.
Thanks for the reply, Doug.

So if I re-wire the crank sensor plug to an existing 5v reference out of the dominator instead of the 12 volt, it should be all good?

I'm not currently running knock sensors, but if I do, i'll cross that bridge when I get there :)
 

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Thanks for the reply, Doug.

So if I re-wire the crank sensor plug to an existing 5v reference out of the dominator instead of the 12 volt, it should be all good?

I'm not currently running knock sensors, but if I do, i'll cross that bridge when I get there :)
We just did the same swap (well, using a 58x wheel in a gen 3 motor though) and yes, the 58x sensor is only 5v volts, where as the 24x was 12v.

As long as your Holley has the options in the ecm to change to run the 58 tooth wheel easily than I say go for it. One less thing to worry about.
 

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so on the same subject if I'm swapping from a gen3 block with rear cam sensor to a gen4 front timing cover setup, does anything need to be changed other than the length of the wires?
 

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I'm curious to know what you ended up doing on your setup.
Should not be that difficult. I'm scratch building a Holley harness, only problem I've found is the shields for the O2 and cam/ ignition pickups is not properly documented in the diagrams. Since I have a TBI Holley HP harness, I had to open it up and look at those points.

The diagrams are otherwise "there."
 
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