I will throw in here as well. As I said at the start, many people use the PSI harness as-is with no problems. I added a fuse box with additional room for expansion - Then if I add something later, it is easy. I used 6 relays, it is all up to you on how you like it. I used a relay for each bank, one for fuel pump, and one for ignition on circuits. Then I clipped on (GM fuse box with provisions for additional relays) two more relays for my Taurus fan control.

 

That's basically what I'm going to have except my current ignition is in one from PSI.

I have no problems splitting them as long as:
1. It'll be helpful in some way.
and
2. I can't trust that PSI's wires are in the exact fuse that their picture says so I'll have to trace each pink wire of theirs back to the computer and figure out which pin does what. Just so I know i'm isolating the coils and not something different.

 

Well here is how I ran things. I feel things are okay but if anyone sees something wired wrong can you let me know?

I know there are different ways to wire some things so i'm not too worried as long as it's not dangerous. (I decided to leave the coils as one for now... can always change that later if i feel like it)

-I was confused is the PSI says "to switched or constant power for fuel pump" Those are two pretty different things... should it be 12v or switched?



also double checking things I noticed the 3 relays i wired up look to be reversed compared to the stock 2 relays PSI did. I went off of how SPAL had their fan relays wired up.
87=yellow wire 12v source
30=big red to fans
85=orange switched wire
86=gray to fan grounds

 

The relay can be fed from either because the computer will not send the switch signal until it gets "switched" or ignition power when key is in start or run. Looks good, and like you will understand your system when you get finished. I think that is always a good thing.

 

85&86 are the "switch" to the coil and can be either + or - BUT, a relay
using a diode across the coil (check on relay diagram) the diode will always be installed in the relay with the stripe on the diode facing towards terminal 86 (reverse biased) and it is important that +12V is connected this terminal, not 85. The diode helps prevent this damage by absorbing the high voltage spikes and dissipating them within the coil/diode circuit.

 

Thanks. I keep looking at SPAL vs. PSI wiring diagrams and feel I have things correct but they are definitely reversed. But as long as they work both ways that's nice to know.


Another thing I noticed. Spal fused the 12v power before it went into the relay where PSI never said anything about that.... said to just supply 12v constant. Does the relay need fused power coming in or since everything after is fused will it be okay? not a super easy fix but doable if needed.

 

The closer to the source you add the fuse the better. If you fuse the source before the relay, you would not need one after, unless it was then split to two different objects and were using smaller wire to them.

 

well here are the new relays I used for the fans.



here are what their old relays said:


I'm not sure I fully understand. You say 86 needs the switched power and 85 needs a ground? Where on all my relays the ground is 85 and the switched power is 86...

 

There are three types of relays
1. your new ones are just a plain coil -85 & 86 can be either +or-
2. your old ones have a resistor across the coil (the box shape across the bottom) 85 & 86 can be either +or-
3. a relay with a diode across the coil (the shape is similar to >| ) this needs + to go to 86

 

OK. I think my brain is finally catching up.

-my new relays have no resister or diode so it doesn't matter which way i wire them.
-my old fan relays had a resister...which is bidirectional and absorbs volt spiking?
-and some have a one way diode. ..making you wire it correctly.

Question is should I have gotten a relay with a resister?

 

You got it. Sometimes when you have high power through the relays, it can cause a spike back through the system when switching. A resister helps with this and a diode is even better protection. I cant say for sure if you needed them or not - sometimes it pays to err on the side of caution. That is probably why (I am guessing) the old relays came with the fan.

 

Okay. SO.... I got everything hooked back up enough to try and start the car and it was a no go. Tries to crank but I near no fuel pump.

So. I check the pump by bypassing the relay and it can easily be heard coming on...so pump is good.


I checked the relay...it clicks when I give it 12v to 85 and ground to 86. So i assume it's okay.

I'm getting 12v to 30 on the relay. but not volts coming out of 87 to the fuel pump.

BUT!!!! I check the PCM signal(85) wire and noticed it's getting a constant 12v....even with the key OFF!!!! which doesn't make any sense to me as that should mean the fuel pump should be turning on all the time no matter what.

So wondering why the PCM is giving 12 constant to the fuel pump wire and how that's all screwed up. and why the relay isn't working even with this screw up.

 

Did you check the 85 wire with the relay plugged in or unplugged? If it's plugged in, you will be seeing voltage coming through the relay coil from 86 looking for a ground.

 

First I would check "ignition on" power to the relay. You should have a constant power input and an ignition on input to the fuses. If you have "constant" power to the ignition on input, it would tell the fuel pump to run all the time. I would not be surprised that the relay is bad. If you have power going in, and can tell the coil is switching, you should have power coming out - if you probe the correct terminal. And +1 for what 75 said.

 

I checked 85 with the relay out.

I'll double check my switched PCM fuses to make sure they're not getting 12v constant.


I do see the PCM has a switched fuse AND constant fuse BUT I have never messed with any of that wiring so should all be good as long as i'm giving it the right switched input.

it definitely seems very suspicious it's a relay issue. But I can't figure out why it's not working when plugged in but when I test it seems to be working.

 

OK. I'm starting to get a bit worried as I don't understand what's going on and it doesn't seem good. I'm getting volts feeding back somehow is the best i can describe it.

Here's my fuse box for reference again:



I have the fuel pump relay disconnect and will worry about that later as i'm still trying to figure out why my switched power isn't working right.

Here's what I have going on:
When I unplug and then plug back in the "switched ignition relay"(bottom left). the pink fuses as well as the 3 fuses in the center cluster(red dakota, orange for fans, and brown for 2nd switched relay) ALL have NO power with key off. and 12v with key on= GREAT!

BUT. when i switched the key back to "off" the center 3 are still getting 5v. and the pink fuses are still getting 12v. UNTIL I unplug the "switched ignition relay" again...then everything resets back to 0.

What I plan on doing:
split the wire coming from IGN spade and have it go to each relay seperatly...instead of one powering the other.

ON the center relay it's the only one i can figure out is wired differently where power is coming into 87 and switched is coming out of 30. all the other have power in to 30, switched coming out of 87

 

I would check the center bottom relay - from ignition. Check for power shutting off.

 

Why are you switching a relay with another relay? Just take the 4 relays and use ignition power to switch them all. The relays draw about 0.16A each so you're adding a 0.64A load to the switch. You've got problems with your core vehicle wiring if you're concerned that the extra load will hurt the ignition switch or the circuit used to get that little bit of power.

Keep your relay wiring consistent for easy troubleshooting. ALWAYS use 30 for power to the relay contact and 87 to feed whatever the relay is switching. ALWAYS use 86 as the coil power and 85 as the coil ground.

Every LS1 diagram I've looked at has the PCM providing power to the fuel pump relay. So, you've got the fuel pump relay wiring wrong.

The resistor or diode across the 85 & 86 terminals is to dissipate the voltage spike caused by switching the relay coil. It has nothing to do with the connected load.

I also wanted to comment on the wiring of the battery. You have a big power lead going from the battery to the starter. The wire is large enough that you can consider any part of that wire to be the same voltage. The alternator applying some kind of "noise voltage" to one end of that wire would just cause that same "noise voltage" to be at the other end. So, that whole argument is silly and meaningless. Take your wiring from either the battery or the solenoid BECAUSE it is more convenient, not because it helps with some kind of "noise" issue. I have seen the results of noise injection testing. You put some kind of noise into the wiring at one spot and it goes EVERYWHERE. Connecting your load to the other end of a big heavy wire 10' away from the perceived source of noise is pointless.

If you go and run a bunch of long small gauge wires from the battery back to the engine compartment then those longer wires will add an extra voltage drop compared to a short version coming from the starter solenoid. If you run longer wires you may also need to run heavier wires.

 

So....

I eliminated the middle relay and had the IGN wire power all 3 switched relays.


WITHOUT the "switched ignition relay" plugged in the IGN wire works like normal. 12v with key on, 0 with key off.


BUT... the second i include the "switched ignition relay" it goes:
0 when key is off.
12v when key is on.
5v to IGN and 12v to pink wires when key is turned back off and stays that way till I unplug the relay to reset things.

 

Something on that relay is feeding power back into the ignition circuit. Try pulling the fuses 1 at a time.

Did you get your fuel pump relay fixed-up so it works?