Wiring for Dummies -101 ... Need advice !!
 

Posted this on the main forum page - thinking it might get some additional info here on the LSX page

I do not know what else to call this post other than that.....

I need some advice / guidance on how to understand wiring

Trying to understand relays - how they paly a part - is the fuse panel sufficient enough or is their another in-line fuse needed in situations ??

What I have
1- New Painless complete wire harness
2- PSI LS3/6L80e Wire Harness
3-Duel Electric Fan setup
4-Aermotive Stealth 340 In tank Fuel Pump

Lets just start with Fuel pump - I thought that would be easy enough but I'm confused - both the Painless and PSI harness have wires for fuel pump. Do I run the hot wire from the fuel pump to the Painless harness ? Is that my "fused" connection -- then I run the PSI Fuel pump wire to the same terminal on the Painless harness?

Fan - same situation - have a spot on the Painless harness for fans but then the PSI Harness Diagram also has two separate wires for fan control. Then when I look up the Spal wiring diagram it shows fuses and relays - how do i separate what is needed and what is not ?

Re: Wiring for Dummies -101 ... Need advice !!
 

some info from the PSI manual and the Painless one

Re: Wiring for Dummies -101 ... Need advice !!
 

Use the control from one harness or the other. I would recommend using the fuel pump and fan control from the PSI harness. The commands will come from the ECM. You will get the prime cycle and any other features to shut off fuel pump in needed situations. PSI fuel pump output is from a relay, wires from that relay can go directly to fuel pump. Think circuit is fused at 30 amps.

The output for fans on the PSI harness (low fan/high fan} are triggers to ground for relays. Relays must be used as the circuit cannot handle the current draw of fans. How you wire the relays for fans is another thing. There are threads that talk about the subject in this forum.

Re: Wiring for Dummies -101 ... Need advice !!
 

Run your fuel pump and fans off the psi harness.. it should already have fuse and a relay for the fuel pump in it.. the fan relays are seperate and need mounted closer to the fans... I assume the painless harness is for the truck.. all you'll need from it a constant 12v and a switch on/crank 12v.l

Re: Wiring for Dummies -101 ... Need advice !!
 

Here is one of the threads I was remembering https://67-72chevytrucks.com/vboard/...d.php?t=835546 about fan in a/c as well.

Re: Wiring for Dummies -101 ... Need advice !!
 

In regards to the relay and fuse locations - do either the fuse or the relay's need to be closer to the actual fan or pump or can I mount them hidden out of sight - like under my dash ?

Re: Wiring for Dummies -101 ... Need advice !!
 

Thanks Richard for that link - even though it adds more confusion in my head it made me think that I'm running a Vintage Air kit so I will need to consider the AC portion when I'm wiring in the fans as well

Re: Wiring for Dummies -101 ... Need advice !!
 

The fuel pump really is in the psi fuse block...itll be fine there.. the relays for the fans, they told me the closer to the fans the better..I mounted mine on the inner fender..been over 15yrs and had no issues with either

Re: Wiring for Dummies -101 ... Need advice !!
 

I'll try to give you a run down of how I did mine.

I ordered battery cables from "batterycablesusa.com" for

Battery Ground to Engine Block (BC#1)
Battery Positive to a junction (BC#2) like this - https://12voltconnection.com/product...ount-red-black
From that junction ordered a cable to go to the starter. (BC#3)
I also ordered a cable to go from the alternator to the starter. (BC#4)

Coming off that junction block. I ran another short cable from batterycablesusa.com(BC#5) to this 150a circuit breaker: https://www.autozone.com/starting-ch...-150/32369_0_0

1. From 150a circuit breaker, I ran a wire to the factory junction block on truck. (Via Fuseible Link like factory) Not sure if your painless wiring harness utilizes this.

2. From 150a circuit breaker. I ran to my FAN relay box( I made my own, but I'll link you to some premade.)
This is the cheapest I could find - https://bp-automotive.com/product/du...fan-relay-kit/
Seems to be wired like POST #5 in this thread - http://67-72chevytrucks.com/vboard/s...d.php?t=784937
This is a nice way to hook them up because your fans are not running full speed when on low and both fans are running, not just one.
Here's a more expensive one that is similar to what I built - https://ceautoelectricsupply.com/pro...ative-trigger/
I have vintage air also, but did not connect the fans to the AC and have not had a problem in Texas(granted I haven't driven it very much). But, usually the engine gets warm enough to engage the fans so it doesn't really matter the AC isn't doing it.

3. (For Fuel Pump) From 150a circuit breaker I ran a 10ga wire to a circuit breaker like this - https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
(you will find a circuit breaker like this on your vintage air harness also) I put this up front on the side of the battery tray, like the junction block and the 150a.
From this circuit breaker, I ran 10ga wire to the relay in the PSI harness. The PSI harness is prewired for this relay, you just need to connect 10ga wire from the battery and from the fuel pump.

4. From the 150a, I also connected the vintage air harness. I reworked it to keep the 30a circuit breaker they include right up close to the battery like I had done with the fuel pump (EDIT to take out 'relay') circuit breaker.


I looked at the Painless wiring instructions, I would disregard anything they have for the fan since you are using the LS computer to control the fans.

I also think you should disregard anything they have for the alternator for the same reason, you are using the LS computer to control it. As long as you have the main lead run back to the battery(via the starter is what I did, that is similar to LS factory wiring) it will work fine. I'm not sure how this will effect the gauge in the truck. I'll see if I can dig into the painless instructions and see.

Fuel pump is all connected to the PSI harness and you only need to power it. 10ga from battery to PSI relay and 10ga from PSI relay to pump.

That's what I did underhood for those 4 main systems. Don't get me started on Dakota Digital and Cruise Control as well as Vintage Air wiring under the dash and the vintage air valve under the hood.

Re: Wiring for Dummies -101 ... Need advice !!
 

I want to add a little bit about the fans. Any of those relay setups I link will require the Blue and Green (Fan 1 and Fan 2 trigger wire) from the PSI harness, as well as switched power to function. I put my fan relays on the core support behind the battery. I don't believe there is a good location to get switched power in that area, so you need to extend it there from somewhere else. I picked mine up at the fuse box. Maybe the painless kit has a lead on the engine side you could use.

I extended switched power, the blue and green from the psi, and the blue wire from the Vintage Air Binary switch and the wiring for the Vintage Air heater valve up to below the battery tray and broke everything off from there.

Re: Wiring for Dummies -101 ... Need advice !!
 

Thanks Jason - this helps a ton

I do have a few questions

1- what's the overall purpose of the 150A circuit breaker
2- the fuses for the Fuel pump and the fans should be as close to the battery as possible I assume.
3- do you have any pictures of your setup?

Re: Wiring for Dummies -101 ... Need advice !!
 

1. The 150a circuit breaker is not needed. I have used it more like 'disconnect' than anything. I seriously doubt I have a wire connected to it that wouldn't burn up before the breaker popped.

2. Yes, as close to the battery as possible. I even took the same stance with the breaker for the Vintage Air, even though their harness would have put it pretty far away. Note I used a circuit breaker for the Fuel pump, like the Aeromotive harness - https://aeromotiveinc.com/product/30...mp-wiring-kit/

3. I'll try to post some separately. It's kind of hard to photograph because it's on the side of the battery tray by the fender. I thought I had some pictures of it before I put the fender on, but couldn't find any.

Re: Wiring for Dummies -101 ... Need advice !!
 

http://67-72chevytrucks.com/gallery/...ttery_tray.jpg

Here's one that I was able to find. The battery is not installed and that's the positive cable dangling on the left side. Then the junction block, fuel pump breaker and then the 150a breaker.

Not installed yet is the vintage air breaker, which I put down lower on the side of the tray.

Re: Wiring for Dummies -101 ... Need advice !!
 

Here's some shots, I tipped the battery out to get a picture of the fuse/relay enclosure and the maxi fuse mounted below it, that I used for fans.

Edit: 3rd picture is completely upside down...but that is the vintage air circuit breaker.

Re: Wiring for Dummies -101 ... Need advice !!
 

Here's an edit made to my above explanation...

4. From the 150a, I also connected the vintage air harness. I reworked it to keep the 30a circuit breaker they include right up close to the battery like I had done with the fuel pump (EDIT to take out 'relay') circuit breaker.

---------
My fuel pump relay is attached to the PSI harness under the seat of my truck and the circuit breaker is on the side of the battery tray.

Re: Wiring for Dummies -101 ... Need advice !!
 

Regarding relay location for fans- As long as relays and wire are rated for needed amperage. Location should not matter much. Maybe make an adjustment if routing to back of truck and back to front. Fuse should always be located close to power if meant to protect wire. If just to protect device it can be right next to it.

Re: Wiring for Dummies -101 ... Need advice !!
 

Thanks Jason and Richard - this really helps a lot. Hopefully this weekend I get some time to start mapping out wire routing and locations

Re: Wiring for Dummies -101 ... Need advice !!
 

Jason -

1- where did you get your relay box - I see some on Amazon but am worried if they will allow for 10 gauge wire - they seem to be more in line with 16 - 20 gauge wire

2- In regards to the fuel pump - the PSI relay is not fuse protected so I will need to add a fuse. Assume that I should run a power wire off the battery - into a 30 amp fuse - then to the relay - then out of the relay to the pump ?

Re: Wiring for Dummies -101 ... Need advice !!
 

like this

Re: Wiring for Dummies -101 ... Need advice !!
 

For the fuel pump. I said above I used a circuit breaker, like is used in the aeromotive wiring kit.

-----3. (For Fuel Pump) From 150a circuit breaker I ran a 10ga wire to a circuit breaker like this - https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
(you will find a circuit breaker like this on your vintage air harness also) I put this up front on the side of the battery tray, like the junction block and the 150a.
From this circuit breaker, I ran 10ga wire to the relay in the PSI harness. The PSI harness is prewired for this relay, you just need to connect 10ga wire from the battery and from the fuel pump.
------
Note I used a circuit breaker for the Fuel pump, like the Aeromotive harness - https://aeromotiveinc.com/product/30...mp-wiring-kit/

Re: Wiring for Dummies -101 ... Need advice !!
 

Alright, my Amazon link doesn't work?

Here it is
https://www.amazon.com/gp/product/B07B934QV1/

Re: Wiring for Dummies -101 ... Need advice !!
 

I'm trying to come up with where I got all the pieces parts for the relay enclosure.

I thought you were going to use the PSI fan harness? I was going to recommend against that in your other thread, but never did. There are some nice pre-wired ls fan relay setups like the one from BP Automotive that I link above. These use 3 relays that run the BOTH fans half speed on LOW and both fans full speed on high.

Re: Wiring for Dummies -101 ... Need advice !!
 

Perfect - Thanks Jason

I'm still looking for a way to house all the circuit breakers and relays that will be bunched together - haven't see anything so far but I'm going to keep looking

Re: Wiring for Dummies -101 ... Need advice !!
 

I have ordered the PSI fan harness but would like to keep those two relays, the Painless alternator fuse. the AC fuse, fuel pump circuit breaker all in one nice location ( hidden in a weatherproof enclosure would be nice. Just so when you pop the hood you dont see all those items

Re: Wiring for Dummies -101 ... Need advice !!
 

here are some thoughts