The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - Wiring for Dummies -101 ... Need advice !!

**Jason Banks** · 12-12-2022, 01:15 PM

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.

12-12-2022, 01:15 PM	#9
Jason Banks Senior Member Join Date: Dec 1999 Location: TX Posts: 1,670	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. Last edited by Jason Banks; 12-12-2022 at 06:08 PM.