MORE lsx wiring questions
 

Bear with me, i searched and couldnt find/understand answers.

My set up (to help answer my questions)

2001 5.3 DBW with 4l60e
Stock harness de pinned via lt1swap.com
current performance (sa-1000) harness (relays/fuses) for lsx

Im sure this is simple for most but not for me (no clue about wiring) so be gentle please.

1. crank signal (out of CP harness) looks to me like it should go to the ST position of the ignition? (only live when you turn key to start?)

2. Battery terminal (out of back of ignition) does this just go directly to battery?

3. TCC brake switch (out of de-pinned ls harness) do i need this? and if so just relay it the way shown on lt1swap.com ?

4. (out of de-pinned ls harness) i have a wire that i labeled (did my de-pin a while ago) starter solenoid/crank voltage D11...any idea where that goes?

5. LAST question for now...the wiring that comes off the 1967 steering column.. is any of that needed to run drive this with above setup? (obviously other than DOT stuff..ie...turn signals and such.

Thanks in advance for anyone willing to help

Re: MORE lsx wiring questions
 

The ignition should wire through a relay so your not putting starting load through the ignition switch.

TCC switch is needed assuming your running an auto with lockup.

Re: MORE lsx wiring questions
 

Guess that (above about ignition) confuses me (not surprised :lol:)
im just use to the 12v battery input on the back of the ignition switch just being fused to the battery and not running through a relay.


Not sure what lockup is or if i have it but ill just wire it in like it shows on lt1swap.com

Re: MORE lsx wiring questions
 

Ignition switches on older vehicles are sometimes run that way, and it can start the truck but you are essentially making the juice for the starter solenoid go all the way from the battery to the fuse then the ignition switch, then down through. This puts all the current (and heat) through small wires. The ign switches on older cars/trucks are heavier and more capable of this, especially when compared to things like push-start switches which are NOT heavy duty at all. The similar principle applies to headlight wiring, using a relay vs hard wiring through the switch.

Modern cars will use the ign switch to carry a signal to the input side of a relay. That relay can then be wired with a heavier wire, and creates a barrier should there be a higher current short at the starter. OR they can use the PCM to send the signal to the relay/starter, depending on the year/type of setup.

Lockup is when the convertor literally locks up at a 1:1 ratio to prevent slip and ideally minimize heat.

Re: MORE lsx wiring questions
 

I pmed u my number. I have used that relay box and fuse box twice. I'll tell what I did. It was easier for me to rewire the box as they wire different.

Re: MORE lsx wiring questions
 

Oh crap, im it trouble then...i have already hooked up everything on the CP fuse box accorind to there instructions. Do i need to cut all the wires and redo everything after i rewire the CP fuse box or can i get away with it the way it is and add the relay for the 12v battery on ignition and a relay for the TCC ?

Re: MORE lsx wiring questions
 

I wont say your in trouble, its just that the directions they send with those boxes doesn't work for my tradition of wiring. they wire the boxes differently. I even called CP for some insight and he blew me off like I was wrong for wiring my relays this way. for instance, when I wire a relay it goes as such:
30- fused Battery power
85- goes to ground (-)
86- signal (fuel pump) (+)
87- to device (power the acc.
the signal (86) can be positive or negative. this is the case when using a lsx pcm. for example, lsx pcm sends a positive signal for the fuel pump but sends a negative signal for the electric fans. so that means that 85 and 86 will require some changes. if the signal (86) is (+) positive then (85) will be negative (-). if the signal is negative, then 85 should be positive. if you pull that box apart you see that its not wired that way. but again, who am I? I rewired the boxes to fit my tradition and they work every time. I cant get my engine to start when I follow their directions. and for my application, I don't use the starter relay. im gonna use that relay for my air bags.

Re: MORE lsx wiring questions
 

Thanks, I see what your saying

Re: MORE lsx wiring questions
 

Got it.. Think im gonna need to pay someone to do this for me. Im completely regretting doing the LS swap cuz of the wiring.

Re: MORE lsx wiring questions
 

thats why i paided to have mine done 225 plus 80 for a hd relay/fuse box i only had to hook up 5 wires! and it start on the second turn of the key

Re: MORE lsx wiring questions
 

Don't know where the subscribe button is for this thread, but Im staying tuned. Lots of very useful info on this thread.

Re: MORE lsx wiring questions
 

thread tools --> subscribe

Re: MORE lsx wiring questions
 

You DA man brew city!

Re: MORE lsx wiring questions
 

I guess the verdict is in. this is officially a lsx swap build help thread. I have completed a few cheap lsx swaps (im no guru). Who has a wiring question? I'll help as much as i can. Trucksters, please dont be afraid to attemp these swaps. Everyone has to start somewhere. How do you know you can't do something if you never attempt to do something? i gotta give a shot out to LS1NOVA71. If you read some of his build threads, you will learn alot. we all can't what he does, but we will never know until we try.

Re: MORE lsx wiring questions
 

I think i might be able to turn the key after this weekend but was wondering if anyone had an answer to numbers 4 and 5 for me.

Re: MORE lsx wiring questions
 

Can we see a pic of that? To run the LSx harness per lt1swap.com, you shouldn't have to run that wire you labelled starter. I wired my using the same directions as you and have my starter is wired straight, without the starter being connected to the harness. The answer to # 5 is no. You don't need the wires from your column to wire to LSx harness. The wire from your column is for light, signals and flashers. Call me. I pmed you my number. I'm doing the same thing your doing, as we speak. I'm using the lq4/th400 setup. I ordered a PCM and wired my harness from lt1swap.com. Brendan is very cool at helping us out with this LSx stuff.

Re: MORE lsx wiring questions
 

None of my gauges are hooked to the computer what so ever they all still are motor senor hook ups this is why I bought the scan gauge 2 so I can compare the 2. Gauges vs computer readings. Nothing has to be hooked up to the LS motor computer unless you bought gauges to hook up that read off the computer. The computer just wants 12 volts when you crank the motor so everything come alive at that moment.
I know enough just to get me in trouble here but I know about the gauges.
;):chevy:

Re: MORE lsx wiring questions
 

I'm sending my pcm to the lt1 guy too. How much did he charge for ur harness?

Re: MORE lsx wiring questions
 

Do you not use the tach signal off the Pcm?

Re: MORE lsx wiring questions
 

BR3W City,
They have it hooked up some place but it's reading about a 1000 RPM's off what the scan gauges say's. I think he put it to a coil pack but not sure. I will find out Friday I guess. It's one of my punch list to do things.;):chevy:

Re: MORE lsx wiring questions
 

If I'm not mistaken, the rpm signal from the pcm is red- # 10 per lt1swap directions. In some cases for the tachometer to read your gauges properly automter sell a box to install to make the tachometer read correctly. The tachometer signal that reads from the scan gauge is correct because that info comes from the pcm itself. And that is the crankshaft sensor. Also, I read somewhere that the tuner for the pcm may need to program the something in the pcm so tachomeyer gauge can read correctly.

Re: MORE lsx wiring questions
 

Some tachs allow you to change the # of cylinders on the signal (4/8), and the output mode can also be changed.

Take a look at the LS2 w/ conventional tach thread, about using a step up resistor for the tach signal. (usually tho, there would be an erratic signal or no reading on the standard tach).

Re: MORE lsx wiring questions
 

Yeah br3w city, thanks for clearing that up. It sounds better the way you say it. Lol. You got that tech talk thing down packed.

Re: MORE lsx wiring questions
 

here is where i found it http://lt1swap.com/vortec_truck_pinouts/2002.htm listed as d11. So as far as wiring your starter direct you just ran the purple off your ignition to starter only? No other wires hook on to the starter? Thanks for your number, if i were to call on the weekend what time is best for you?

Re: MORE lsx wiring questions
 

please dont call me when im sleep. that is how i stay energized to be able to work on lsx swap. California, i think is 3 hours behind Miami, Florida. I am mainly free during the evenings. Question, are you using the stock under hood fuse block? if you not using the stock fuse block, i wouldnt worry about that. if you rewiring your harness for stand alone opration, just follow Brendan's instruction. just make sure your lsx starter/solenoid is wired in the normal fashion.

Re: MORE lsx wiring questions
 

Ill be using the current performance for relays/fuses for the motor and then a painless for the chassis. (if that makes sense). So starter/solenoid wired normal would be 12v to starter from batt and feed from ignition (start) to solenoid correct?

Re: MORE lsx wiring questions
 

That would be correct.

Re: MORE lsx wiring questions
 

thanks

Re: MORE lsx wiring questions
 

EPIC FAIL.....tried to start the LS on sunday (yes the pressure was on with all my buddys standing around watching football and heckling me)..At first i had the starter wired through the Current Performance fuse/relay as per their instructions...turn the key..NOTHING...then i rewired the starter the standard way and the starter turned over but was very weak as if i had a dead battery...(battery was at full charge) Any thoughts?

Also, isnt the fuel pump suppose to kick on then the key is turned? During several attempts to turn the key only once did i hear the pump turn on and it ran continuously until it switched the key to the off position. The system is new do i need the purge the lines somehow? Any thoughts?

Re: MORE lsx wiring questions
 

And another couple questions....

I dont have the TCC wired up yet per lt1swap.com but im not tring to drive it yet just start it, does that matter?

And when wired correctly should the pedal (DBW) move the throttle body butterfly (for lack of a better term) when pressed while the key is on? Because mine does not..

Re: MORE lsx wiring questions
 

Are your battery cables good? Connections tight? Have a good ground to the engine block?

Fuel pump should come on when the key is turned on and run for two seconds unless the engine starts, then it should run constantly. You shouldn't need to purge the lines, the injectors will open and let any air out.

TCC doesn't need to be wired up for the engine to start.

Usually the butterfly will work with just the ignition on, but I've seen some where it only works when the engine is running.

Re: MORE lsx wiring questions
 

Ground to engine block...GREAT CALL..i dont think i have one..just grounds in harness and on battery. I can just ground block to frame because battery is ground to frame correct?

Re: MORE lsx wiring questions
 

You need a ground from the engine to the frame, and you could do it that way, but you'd be better off to hook your negative battery cable directly to the block (preferably as close to the starter as possible) and then run another ground strap to the frame.

Re: MORE lsx wiring questions
 

When you go key-on, you should hear the fuel pump relay prime the fuel pump, and you should also hear a *click click* as the throttle blades do a min-max test to make sure that their sensors and servo's match (double checking itself, should something cause them to get out of phase, this would re-cal them).
If you don't hear that, then your DBW isn't wired properly. If you DO hear that, but then lose throttle control at the first input, then you probably have a component mismtach.

Re: MORE lsx wiring questions
 

Made sure the block was grounded to frame. I do get continuity throuout the whole truck whentesting ground..My battery is in the rear of the truck, Should i run a ground from battery to block?

Re: MORE lsx wiring questions
 

Great, i dont hear that at all. Time to start checking that. That shouldnt prevent the engine from cranking over like normal right? Possibly wont start but in cranks over like i have a dead battery but thats not the case.

Re: MORE lsx wiring questions
 

The further away you mount the battery the more important it becomes to have good battery cables, both positive and negative. Sure you'll generally get continuity through out the whole vehicle, but it has to be able to handle the amp load the starter draws. You could have a very small wire that's giving you continuity, I once had an engine ground it's self through the metal oil pressure line, definitely not good. You can run your ground to the frame from the battery, but a steel frame isn't as good of a conductor as a heavy gauge copper battery cable. But if you don't have at least a big ground cable from the frame to the engine block, it's not going to start as well as it should, and the hotter the starter gets the harder it will get to start.

Re: MORE lsx wiring questions
 

Ok..ill grab a monster ground cable today and try that out.

Re: MORE lsx wiring questions
 

Strangely, my optima is rear mounted, and I don't run an extra cable from battery to block.
I have heavy gauge cable grounding to the frame, then my big 3 grounded up front.

Re: MORE lsx wiring questions
 

So i put a 4 gauge ground strap from the frame to the block and it still didnt change the fact that doesnt want to turn over..trys a little like the battery is almost dead but i know the battery is solid..Could it have anything to do with the engine harness? My thoughts are NO..it should still crank hard just might not start.