fuse/relay block on reworked harness

[bigmoe]

I sent my harness out to be reworked to the guy Brendan at LT1swap.com recommends. It will be a while before my truck is back from paint and I get the engine installed. (08 Gen 4 5.3) I pulled the harness out to have a look and it looks like he did a really nice job. I find it odd though that there are no fuses installed and they are not labelled. The wire ends are labelled: 12v, 12v, 12v keyed, fuel pump, and fan +. I tried checking continuity from each of those wires to the fuse locations and got nothing (probably because the relays have to be activated?). I've emailed the guy but got no response so far. Any ideas how I can figure out the fuses? I assume the relays are main, fan and fuel pump. It would be nice if they were labelled too.

[Gregski]

I really don't like how he combines so many components onto one fuse, here's how Brandon makes his, so see if this helps they look the same

Fuse Block and OBD2 Port Wiring Information

[weedoublewide]

Originally Posted by bigmoe

I sent my harness out to be reworked to the guy Brendan at LT1swap.com recommends. It will be a while before my truck is back from paint and I get the engine installed. (08 Gen 4 5.3) I pulled the harness out to have a look and it looks like he did a really nice job. I find it odd though that there are no fuses installed and they are not labelled. The wire ends are labelled: 12v, 12v, 12v keyed, fuel pump, and fan +. I tried checking continuity from each of those wires to the fuse locations and got nothing (probably because the relays have to be activated?). I've emailed the guy but got no response so far. Any ideas how I can figure out the fuses? I assume the relays are main, fan and fuel pump. It would be nice if they were labelled too.

If you pull the relay's and look on the underside of the relay, it should have numbers.

On one relay block, your 12V+ key'd will be landed on PIN 30.
On that same block, the fuel pump will go to Pin 87 ( this is your output that turns on your fuel pump)
On that same block, The fuel pump control goes to pin 86.
Pin 85 goes to ground

On the other relay block:
Pin 85 goes to ground again.
Pin 30 will be 12V+
Pin 86 will be your 12V+ Key'd
and Pin 87 is what feeds your fuse block.

Now your fuse block will consist of your fuel injectors, mass air flow sensor, TAC module, O2 sensors and etc.

It's had to tell which fuse powers what because it depends on how he spliced the wires together.

I mean you could go all the way to the connector and ohm it to the fuse and that would tell you what's what.

double

[bigmoe]

Originally Posted by Gregski

I really don't like how he combines so many components onto one fuse, here's how Brandon makes his, so see if this helps they look the same

Fuse Block and OBD2 Port Wiring Information

He makes them the same as the LT1swap.com tutorial but added an extra relay for a fan for me.

[Gregski]

Originally Posted by bigmoe

He makes them the same as the LT1swap.com tutorial but added an extra relay for a fan for me.

Yes I meant I didn't like how Brandon at LT1swap.com did it, which this guy followed. I prefer to keep my Injectors on two separate fuses for example one fuse for the Odd ones and the second for the Even ones, like the factory did it.

[Daaaanz67]

Originally Posted by Gregski

Yes I meant I didn't like how Brandon at LT1swap.com did it, which this guy followed. I prefer to keep my Injectors on two separate fuses for example one fuse for the Odd ones and the second for the Even ones, like the factory did it.

Just FYI, I did the same as you with the injectors and separate fuses. (Like factory). I had a problem where my truck completely shut off and would not start. After checking everything with fuel spark etc., I could not get the truck to start. It had everything that was necessary for an engine to run. It wasn’t until I did an individual injector fire test that I discovered that the even side injectors were not firing. When I first checked for fuel flow I only checked the odd side and I was getting fuel by seeing the spark plugs were wet. After tracing my harness back to my fuse block, I discovered that the connector that the fuse plugs into had backed its way out of the fuse block. Only on one side of the block. I did not build the fuse block, it was by Current Performance. I also noticed that the fuse was discolored on one spade. This was due to the bad connection causing arch/heat. This attributed to my no start at times. It happened about four times over a five year span. If I had to do it all over again, I would run one circuit for injectors. Anyway thought I’d share my experience with the separate circuits. Funny how it didn’t even act like it wanted to run with one bank getting fuel.

[Daaaanz67]

Forgot to add it’s been about nine year since the swap and that was my only problem. Everyone check the connection at the fuse block and make sure the connector is fully seated. Don’t rely on the builder. Check their work.