ECM and under hood wiring - 8-12-08

MalibuRacing

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May 5, 2003
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Got my PCM and wire harness back today. I'm OK with the quality of work, but there is NO instructions whatsoever on how to connect some wires. The only documentation was wiring diagrams for the 2004 vehicle that my engine/PCM/harness came out of. ](*,) I've been told that the guy gives great tech support, so I'll be on the phone with him tomorrow. :roll: It would be much better for him and me to have included some basic wiring instructions. Guess you get what you pay for, but it was at least half price of what most others charge. Oh well, I'll give a more detailed run down on wiring connections when I actually start digging into it. For now, I've just made some basic connections, like coil packs, injectors, sensors, grounds, etc.

The battery will be relocated to the drivers side. I will need to figure out a way to mount the PCM on the driver's side wheelwell. I've got to run the looms behind each cylinder head to connect to the oxygen sensor on each side and transmission connections. I know, it looks like a total mess now, but I'll get everything cleaned up and tidy.


Here's the wires that are from the Malibu factory harness. They are the starter and alternator connections. I will need to figure out how to migrate this with the new harness and PCM. I plan on using the factory malibu starting circuit (obviously), but I've got to figure out how to do the alternator connections. Right now I have all the 2004 harness connections going to the alternator. But, what do I do with all the old Malibu alternator wiring? :-k Like I said, got some studying to do.



This can't be good can it?? This is the factory Malibu A/C connector. When I removed the loom, the black wire was inside the loom and not connected to anything. Is this normal? I'm guessing the compressor is grounded through the chassis? Should the black wire be connected? Gotta' look at the wiring diagrams.



What the heck does this connect to? I'm thinking the single wire connector is for the oil pressure idiot light. The coolant idiot light connector is on the other side (driver's side). I'm not sure about the other connector. Any ideas?



What about this connector? Not sure where it goes? It's next to the A/C stuff, but I cannot remember what (or if) it connects to.



So, I'm about to do some studying of wiring diagrams and schematics. I do this kind of stuff for a living, so I should be able to figure it out. I just hate to bring my work home. ;)

I'll be sure to give detailed instructions on all the connections and try to document it as well as I can. Until next time.....
 

RatMalibu

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May 21, 2003
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Re: Update - 8-12-08

the 2 connectors you asked about on the bottom pics....plug them into each other ;) the large red is the blower motor high speed feed...the smaller ones iirc are the rest of the blower motor wires...though imo you are better off doing away with the connector...its a common high resistance spot (they melt easily)

the A/C plugs black wire you can just ground if you still need it for anything...

and truthfully with the alternator wiring the only wire you NEED from the original harness is the small "exciter" one so the alt knows when to charge. I run a 8ga wire from the large post straight to the battery instead of using the factory mess....you might need to tie the exciter wire into your PCM though....better ask your guy that did the harness
 

Doober

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Jun 2, 2003
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Re: Update - 8-12-08

X2 on checking with the harness/exciting wire. I seem to remember seeing someone asking "doesn't the alternator get turned on by the PCM" or something to that extent, so it puts a big question mark in my head that I myself want to find out before diving into the LS world.

The green wire goes to a)temperature light switch (dummy lights) or b)temperature gauge sender (round gauge package). The tan wire would be for the oil pressure switch/sender. That stock alternator 2-wire plug is basically the same thing as the rest of the newer alternators, the larger red wire is a constant 12v feed to the alternator (so you could actually tie it to the BAT terminal of the alternator had you been sticking with a traditional SBC and shaved a little wiring out of your harness), and the other is the same as the newer alternators, a wire that tells the alternator to 'turn on' when it's energized.
 

MalibuRacing

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May 5, 2003
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Re: Update - 8-12-08

Thanks for the tips. I guess I had a "DUH" moment not figuring out that the two connectors go together for the A/C blower stuff.

As for the Alternator, if you look at the picture below, you can see that I'm using the Tahoe battery connection setup. See the little red box below and right of the alternator on a bracket. If you notice, it has a small black wire running out of it (connects to battery cable) that is connected to the battery supply of the alternator. I'm pretty sure the PCM controls excitation to the alternator, but I will ask the guy that did my harness to make sure. All the connectors are there and connected from the Tahoe harness that connects to the alternator. I just need to figure out which wires on the Malibu Harness to get rid of and which ones to keep to supply needed power for the accessories, lights, etc. for the rest of the car.
 

78_Elky

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Mar 9, 2005
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Re: Update - 8-12-08

I went through the same thing when I rewired my car a few years ago. My advice to you is to lay it out and really think about each little bit you need. I mean for lights its pretty simple they just need power to the switch which will be always energised and then send the wires to the lights themselves. The other stuff you'll need is really just your wiring for your ignition switch. The rest of the stuff is just gonna work from that unless you've taken all your wires out from the factory.

Good luck
 

455_82malibu

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May 19, 2006
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Re: Update - 8-12-08

the new engine computer will control the alt, you should have a plug that goes into the alt. All you will use for the car side is the main hot wire (clumped toghter and was attached to the rear of your old alt) this will power the car fuses and accessories, you can connect that to the new alt or to that red power supply box. you will need a few hot and key on hot wires for the new compter, but you can tap into the malibu fuse panel, use the IGN and BAT spaces.

Did you get all the relays or making your own panel?
 

Deuce4935

Frequent Racer
Nov 19, 2007
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Chicago, Il
Re: Update - 8-12-08

MalibuRacing said:
Thanks for the tips. I guess I had a "DUH" moment not figuring out that the two connectors go together for the A/C blower stuff.

As for the Alternator, if you look at the picture below, you can see that I'm using the Tahoe battery connection setup. See the little red box below and right of the alternator on a bracket. If you notice, it has a small black wire running out of it (connects to battery cable) that is connected to the battery supply of the alternator. I'm pretty sure the PCM controls excitation to the alternator, but I will ask the guy that did my harness to make sure. All the connectors are there and connected from the Tahoe harness that connects to the alternator. I just need to figure out which wires on the Malibu Harness to get rid of and which ones to keep to supply needed power for the accessories, lights, etc. for the rest of the car.
If you along the firewall you should see a metal tube about 8" in length with some wires running inside of it, those are the wires that connected to the original eng's starter. Connect them to the starter on the 4.8 and that gives you your lights, windshield wipers and etc.
 
A

Anonymous

Guest
Re: Update - 8-12-08

i got a couple quick questions because im startin on a similar project but im usin a 6.0L

1.)wut kind of manifols/headers can i use and wuts tha cost?

2.) wut would be the best intake 2 use since i wanna use a carb.?(cost?)

3.)wut would be the best trans 2 use? and will i have any trans mount issues!?
 

MalibuRacing

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Re: Update - 8-12-08

It all depends on what you're trying to build. A street/strip car, daily driver, race car?

I believe Roller406bu is using F-body (Camaro/Firebird) Pacesetter headers. I use stock F-body manifolds.

Edelbrock offers either a single plane or dual plane intake for carb that comes with the ignition control box for the coil packs. It's pricey, around $700 for the intake and ignition.

Again, transmission depends on what you want to use it for. If you're building a drag car, then a TH350 or TH400 would be your best (economical) bet. You'll have to get an adapter plate for the LSx engine. I'm running a stock 4L60E transmission to get good gas mileage. I got a crossmember from "Iceman" (see sponsors above).

I suggest you (re)ask the question in the LSx forum. I'm building mine for a 16 year old as a daily driver, so it's a conservative setup. Others can give you more information on a performance application.
LILBULL81 said:
i got a couple quick questions because im startin on a similar project but im usin a 6.0L

1.)wut kind of manifols/headers can i use and wuts tha cost?

2.) wut would be the best intake 2 use since i wanna use a carb.?(cost?)

3.)wut would be the best trans 2 use? and will i have any trans mount issues!?
 
A

Anonymous

Guest
Re: Update - 8-12-08

MalibuRacing said:
It all depends on what you're trying to build. A street/strip car, daily driver, race car?

I believe Roller406bu is using F-body (Camaro/Firebird) Pacesetter headers. I use stock F-body manifolds.

Edelbrock offers either a single plane or dual plane intake for carb that comes with the ignition control box for the coil packs. It's pricey, around $700 for the intake and ignition.

Again, transmission depends on what you want to use it for. If you're building a drag car, then a TH350 or TH400 would be your best (economical) bet. You'll have to get an adapter plate for the LSx engine. I'm running a stock 4L60E transmission to get good gas mileage. I got a crossmember from "Iceman" (see sponsors above).

I suggest you (re)ask the question in the LSx forum. I'm building mine for a 16 year old as a daily driver, so it's a conservative setup. Others can give you more information on a performance application.
LILBULL81 said:
i got a couple quick questions because im startin on a similar project but im usin a 6.0L

1.)wut kind of manifols/headers can i use and wuts tha cost?

2.) wut would be the best intake 2 use since i wanna use a carb.?(cost?)

3.)wut would be the best trans 2 use? and will i have any trans mount issues!?


well yea tha intake aint cheap at all. and i wanna use it 4 street/strip. adn i wuz bout usin the 4L80e trans. but wut adapter plate r u refferin 2?
 

Deuce4935

Frequent Racer
Nov 19, 2007
341
0
0
Chicago, Il
Re: Update - 8-12-08

LILBULL81 said:
MalibuRacing said:
It all depends on what you're trying to build. A street/strip car, daily driver, race car?

I believe Roller406bu is using F-body (Camaro/Firebird) Pacesetter headers. I use stock F-body manifolds.

Edelbrock offers either a single plane or dual plane intake for carb that comes with the ignition control box for the coil packs. It's pricey, around $700 for the intake and ignition.

Again, transmission depends on what you want to use it for. If you're building a drag car, then a TH350 or TH400 would be your best (economical) bet. You'll have to get an adapter plate for the LSx engine. I'm running a stock 4L60E transmission to get good gas mileage. I got a crossmember from "Iceman" (see sponsors above).

I suggest you (re)ask the question in the LSx forum. I'm building mine for a 16 year old as a daily driver, so it's a conservative setup. Others can give you more information on a performance application.
LILBULL81 said:
i got a couple quick questions because im startin on a similar project but im usin a 6.0L

1.)wut kind of manifols/headers can i use and wuts tha cost?

2.) wut would be the best intake 2 use since i wanna use a carb.?(cost?)

3.)wut would be the best trans 2 use? and will i have any trans mount issues!?


well yea tha intake aint cheap at all. and i wanna use it 4 street/strip. adn i wuz bout usin the 4L80e trans. but wut adapter plate r u refferin 2?
Depending on what year 4l80e you're thinking of using, you may not have to get the adapter plate. The adapter plate is necessary when putting a different trans behind the LSx blocks if the trans doesnt have the correct bellhousing, its actually a crank spacer. As for the intake, Ive got a brand new GMPP single plane for that setup, and the MSD 6010 is the best controller to purchase because it allows you to program and tune better than the box that Edelbrock gives with its combo package.
 
A

Anonymous

Guest
Re: Update - 8-12-08

Edelbrock offers either a single plane or dual plane intake for carb that comes with the ignition control box for the coil packs. It's pricey, around $700 for the intake and ignition.

Again, transmission depends on what you want to use it for. If you're building a drag car, then a TH350 or TH400 would be your best (economical) bet. You'll have to get an adapter plate for the LSx engine. I'm running a stock 4L60E transmission to get good gas mileage. I got a crossmember from "Iceman" (see sponsors above).

I suggest you (re)ask the question in the LSx forum. I'm building mine for a 16 year old as a daily driver, so it's a conservative setup. Others can give you more information on a performance application.
LILBULL81 said:
i got a couple quick questions because im startin on a similar project but im usin a 6.0L

1.)wut kind of manifols/headers can i use and wuts tha cost?

2.) wut would be the best intake 2 use since i wanna use a carb.?(cost?)

3.)wut would be the best trans 2 use? and will i have any trans mount issues!?
[/quote]



well yea tha intake aint cheap at all. and i wanna use it 4 street/strip. adn i wuz bout usin the 4L80e trans. but wut adapter plate r u refferin 2?[/quote]
Depending on what year 4l80e you're thinking of using, you may not have to get the adapter plate. The adapter plate is necessary when putting a different trans behind the LSx blocks if the trans doesnt have the correct bellhousing, its actually a crank spacer. As for the intake, Ive got a brand new GMPP single plane for that setup, and the MSD 6010 is the best controller to purchase because it allows you to program and tune better than the box that Edelbrock gives with its combo package.[/quote]



SO WUT TRANS WOULD BE BEST 4 STREET/STRIP APP.? AND I WUZ JUST THINKIN BOUT BUYIN A INTAKE AND THEN FIGURE OUT WHICH MSD BOX WOULD WORL BETTER AS FAR AS TUNIN THE MOTOR!! THANKS 4 THE INFO Deuce4935!!
 
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