samh_08

I have been labeling and narrowing down what I need and dont need, but I am having inconsistency in wiring. I supposedly bought a harness and PCM out of a 03 GMC Yukon have have a 2005 LQ4 out of a chevy 2500. Whether or not that is true, I do not know because I dont really trust the seller. Is there any way to know for sure?

Here is a list of stuff I would like if possible:
1.) Electric fan control via PCM
2.) DBW throttle body converted to cable (what needs to be changed)
3.) Low oil pressure shutdown (possible)
4.) Rear o2 sensor delete
5.) EVAP and all unessessary emissions delete
6.) Any other cool features possible?


I was also wondering if I have to change the PCM operating system to be able to run electric fans and a cable throttle body. I noticed that I did not have a OB2 connector, is this normal and what do I need to wire one up.

Sorry for all the questions but Im new to the kinds of things can actually be changed and modded with these engines. Please let me know, Thanks.


Sam

G-Body

iTrader: (4)

1. Yes fan control is possible, you just need to enable it in the pcm
2. Yes, you need to add IAC and TPS wiring. The biggest obstacle is the IAC driver controls. if your PCM has blue and green connectors it may not have IAC drivers and would need to be replaced with a B/G one that did, or with the older red and blue PCM.
3. I don`t know, I haven`t heard of that feature before
4.Yep, yank the wiring and remove the codes.
5.same as #4
6. Yep you can enable the tow/haul mode with a momentary button/...that gives you the opportunity to have 2 different shift settings for the trans, one for crusing and one for performance

Old Kid

I'm also new to these engines and just modified a 99 fbody harness for my project. The info and pinouts found in this forum were invaluable. (check out all the stickys and faq) I also used the underhood harness and parts of the body harness. I spread everything out on the garage floor, armed myself with some electrical tools and a big stack of wiring diagrams and pinout sheets, and started tracing and removing wires. It may be less confusing to look for the wires you will need instead of just looking for wires to remove. This will help you better understand how the system works. If you can't grasp the operation of a relay, you may be better buying a premade harness.(not trying to insult you!) Also, what vehicle is this going in? Why get rid of the dbw?

the_merv

iTrader: (88)

I built my Harness from a '99 LS1 Harness from a Camaro.

ryanvv355

iTrader: (17)

You can convert to cable TB and an earlier O.S. Here is how I do it:

Cut the wires for the TB connector pretty close to the connector, Now you will have 8 wires open at the TB that run to the TAC module. Cut the wires at the TAC module. Splice or solder together the wires going to the TAC module and run wire over to the PCM, pin the PCM for a 2003 Express Van 2500. If you have your harness completely torn down then just run new wire from the PCM to the TB. There is one of the A/C sensors that will work for the TPS connector, If you have eliminated A/C the reuse of the connector will save you some money. Get a PCM or have yours tuned for a 2003 Express Van and you have cable drive TB.

Fan controls are in most computers so you just need to tune them in. You need to be careful on which PCM you use for the DBW to cable swap, Delphi deleted the IAC driver in most 03 and later PCMs due to GM mainly using DBW at that point.

samh_08

Im good with electrical (put in remote starts for a winter job) so that is not an issue, I just would like solid information to know what I can and cant do. I am getting rid of DBW because I never received the TAC module and pedal and would just rather have my foot be connected directly to the engine. I have access to Mitchel online for auto repairs and stuff so I can look at whichever PCM pinouts I want to, I just dont know which one I should or can go by being I have a 05 chevy LQ4 and 03 Yukon wiring harness.

Two questions that I know of havent received a response..
1.) How can I know forsure which harness and PCM I have?
2.) If I am supposed to have the OBD2 connector included already in my harness, or how to add it.?

Thanks for the info so far,
Sam

G-Body

iTrader: (4)

I don`t know if there are any p/n`s on the harness to differentiate which one it is. In reality it doesn`t matter much, you just need to make sure that the wiring connections match up with what you have the PCM programmed for.

For the PCM there should be a sticker/piece of paper attached to is that has the service # and hardware # on it. You can determine what applications it was used for by looking up the service # in the PCM section.

The OBD II connector is part of the dash harness so you probably didn`t get it. It is a 4 wire hookup (2 grounds, bat + power and then the serial data wire to the PCM). You can use the OBDII connector out of any 96 or newer car that was sold in the US as they are all the same.

samh_08

I did a search for info on my service and hardware # and didnt come up with anything solid. One person was saying that only PCMs with the blue and red connectors had IAC drivers, whether or not that is true though...

If this helps anyone with my questions:
Service number = 12589462
Hardware number = 12589161 (I have blue and green connectors)

poconojoe

iTrader: (43)

That's a 2005 2006 drive by wire PCM, I don't think you can use it, since it most likely doesn't have IAC drivers in it.
The only green and blue pluged PCM, that I know of that still had IAC drivers in it, is the 2004 service number 12586243

It doesn't mater which PCM you use with low oil pressure shut, since you use a mechanical switch to kill the fuel pump relay and it doesn't go through the PCM

By the way you should be able to just switch the caps from green to red, once you install your TPS and IAC wiring and use one of the Blus and Red plugged PCM's like the 12200411 or one of the several other 1999 through 2002 PCM's

samh_08

How do you know all of that? Is there a chart or something I am missing? Why did everyone tell me that it doesnt matter which pcm/harness combo you get because you can mod any one to your needs....

Anyone else?

69 Ghost

What you need to do is check your PCM for the part number. If this is a 04 it may be the same one used on a Vette and an 04 GTO. The 04 GTO is a cable setup so you could have your pcm flashed to the GTO tune and then use the pinout for that car and it will work fine. The older PCM's have both DBW and cable setups. Either way don't cut the wires! Get a pin removal tool and you should be able to use those pins for the IAC TPS conectors and repin it at the PCM. I would be interested in swapping you if you have the TB and the gas pedal. I am just getting ready to finish my setup by mounting the cruise control and throttle control box on my car. I am interesed only because it is cleaner under the hood. It appear to be easier to go to a DBW than a cable if you want to use a cruise setup if not then it is very similiar. Shoot me an email I should be able to help you with a reflash for a minimal cost even if you already have the right setup.

69 Ghost

Your PCM can be reflashed to a 04 GTO no problem and you can use your PCM for a cable setup and tuned from there. Your fans are not a problem. I believe the trucks used a clutch fan setup so you would have to wire it from your pcm to a set of relays to run the fans. When you hook up to the PCM you will be able to tell what the PCM came from. I am not sure of the low oil pressure setup but the older TPI setups had a oil pressure cutoff switch that was tied to the fuel pump relay independent of the PCM. I believe that GM did away with that setup but I have not checked that out.

http://www.turbo-owners.com/forum/ge...ech-flash.html

busta9876

iTrader: (3)

Have to be watch out if using 04+ harness and changing the color caps to use 99-02 PCM. On most of the 03 or 04+ the PCM controls the GROUND for the Oxygen Sensor Heaters. In 99-02 applications, the O2 heaters went directly to engine ground. That is the only thing different that would keep you from using a 99 PCM on an 05 harness. If you find the grounds, pull them out of the PCM connector and run to engine block, add you're IAC, TPS wires, change from green to red caps and you're 05 harness is ready for any 99-02 PCM.

69 Ghost

I didn't know about the 02 grounds but personally I would not go back to a 411. I currently have a 98PCM and when I jump my plan will be to the latest which will be the 253 or similiar. Coming from the TPI world a year or two made a huge difference in how the cars ran. Some guys think that there is no real running difference but the PCMS keep getting smaller and faster. That along with newer and more GM code allows more control and capability.

poconojoe

iTrader: (43)

He listed his service number as 12589462, it isn't on the list of interchangable Blue and green plugged PCM's that I have. Which include
12576106
12583560
12583561
12586242
12586243
12589463

By the way, why do you feel that DBW makes the the under the hood look cleaner? You have more wiring and a TAC module to deal with. I know everybody is intitled to their opinion, but cleaner to me means less stufff.

Jones'n

I think the DBW is cleaner too, it just looks cleaner when you don't have the throttle cable strewn across the engine, no linkage sticking out of the TB, and if you have cruise control, no 2nd cable strewn across the engine.
The electronics for the DBW are easy to hide, and CC is simple to add in.

samh_08

Alot of opinions and different info....

I would use DBW and eliminate this problem if I had the pedal and TAC module and they werent so damn weird feeling to drive around.

Is it true that they are more difficult to tune as well?

69 Ghost

Been researching the difference. There is a TPS, IAC, Cruise Module, Throttle Module in a cable setup. The DBW takes care of all of that with a motorized TB and a gas pedal that I believe is controlled through a TAC module. If you look at the differences it still uses a motor either at the cruise module or at the TB. Most guys don't like the delay on the DBW that can be tuned out but like the cruise better. Take your pick.

poconojoe

iTrader: (43)

What throttle module on the cable setup?

waynehartwig

So is cruise on DBW all done through the PCM? I've looked at a pin out and don't see it listed...