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Should they be fused?

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Old Dec 23, 2012 | 07:26 PM
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Default Should they be fused?

Should these wires be fused?

The hot wires to the relays activating the FANS and ECM? I suspect no...but not sure.

Last edited by badazz81z28; Dec 23, 2012 at 07:31 PM.
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Old Dec 23, 2012 | 07:48 PM
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Look at a factory wiring diagram they will be fused. Fan will be 40-50amp, Ecm 10-20amp
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Old Dec 23, 2012 | 08:04 PM
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The fan schematic is in the first post, in this link, and has the fuse size.

https://ls1tech.com/forums/conversio...chematics.html
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Old Dec 23, 2012 | 08:51 PM
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I'm having a hard time reading that diagram...You are both referring to the relay activating power and not the main power right? These 12V wires are for activating the solenoids, not powering the components. Still say they need to be fused?
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Old Dec 23, 2012 | 09:08 PM
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Yes they are fused
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Old Dec 23, 2012 | 09:15 PM
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I took a look at the diagrams again. Its a good thing...Looks like the Fan Relays are wired always HOT with a 10 amp fuse.

I didn't see anything for the ignition switch...The power to the relay to turn the ECM on. This 12V wire powers the relay to ground. It does not power the ECM
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Old Dec 24, 2012 | 05:41 AM
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Originally Posted by badazz81z28
I took a look at the diagrams again. Its a good thing...Looks like the Fan Relays are wired always HOT with a 10 amp fuse.

I didn't see anything for the ignition switch...The power to the relay to turn the ECM on. This 12V wire powers the relay to ground. It does not power the ECM
Look at the other schematics. There is one that has the fuse sizes for the ECM, also.
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Old Dec 24, 2012 | 11:05 AM
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I think I will fuse it anyways, but according to that schematic it doesn't looked fused. In my harness that relay I keep referring to as the ECM is actually acting as the Power-train ignition in the PSI harness to start the whole system.
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Old Dec 24, 2012 | 05:56 PM
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Then the wire you will be triggering the relay from is likely already fused before the ignition switch
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Old Dec 24, 2012 | 07:00 PM
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The wire coming from the pcm is just a ground trigger
It does not get a fuse.

The fuse is on the hot activation side of the Relay... its part of a group of ignition on hot wires
The fan master power has a fuse on the always hot from battery power That connects to pin 87 of the relay
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Old Dec 24, 2012 | 08:33 PM
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Originally Posted by soundengineer
The wire coming from the pcm is just a ground trigger
It does not get a fuse.

The fuse is on the hot activation side of the Relay... its part of a group of ignition on hot wires
The fan master power has a fuse on the always hot from battery power That connects to pin 87 of the relay
Yes, the wires in question are the Hot 12V sources for relay activation. With my harness from PSI I have to hook these up.
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Old Dec 24, 2012 | 08:39 PM
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I'm not sure of how your harness is built, but it sounds like you are either saying it is built incorrect, or they did t give any instructions for termination...

Add a fuse in-between your ignition hot 12v activation wire and the relay, and use the pcm to trigger the ground side of the coil on the relay(pin 85 or 86)
Pin 30 is connected to the chassis ground, and pin 87 is connected to a Fuse and your main power source for the fans.

Last edited by soundengineer; Dec 27, 2012 at 05:20 PM.
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Old Dec 24, 2012 | 08:43 PM
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Also, you can make a main junction point for all of your ground activated relays so that you can use one fuse, and branch off to all your relays.
But that only works for relays that are ground activated.
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Old Dec 24, 2012 | 09:24 PM
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Originally Posted by soundengineer
I'm not sure of how your harness is built, but it sounds like you are either saying it is built incorrect, or they did t give any instructions for termination...

Add a fuse in-between your ignition hot 12v activation wire and the relay, and use the pcm to trigger the ground side of the coil on the relay(pin 85 or 86)
Pin 30 is connected to the chassis ground, and pin 87 is connected to a Duse and your main power source for the fans.
That is what I did. The relay coil itself does not draw much current, maybe 200 milli-amps. So I put a 5 amp fuse in the 12V power circuit for each relay to be on the safe side.
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