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Need help on PCM and Harness

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Old 06-12-2006, 11:23 AM
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Default Need help on PCM and Harness

I have been getting conflicting info on which PCM and harness to use. I bought a 02 6.0L out of a 4x4 Surburban and I am putting it in a 92 Camaro. I am trying to figure out what year PCM and wiring harness to choose for this swap. I have heard any year (98-02) will work then I hear that you can only use (01-02). I am trying to figure out what year or years will work. Also when I try to buy a harness, people are telling me that a 4x2 harness will not work and I should get a 4x4 harness even though I am only using the engine and not the 4x4 unit. I would like to find a PCM and harness first before going to any of the sponsors and getting one made. Any help is greatly appreciated.
Old 06-12-2006, 12:19 PM
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The '97-'98 PCM is peculiar. I found out too late.
Old 06-12-2006, 07:09 PM
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If your going to go with a stock harness then forget the '97-98. They just arent able to be programed as easily and you wont have alot of the features you will with the '99-up if you are tuning using any of the programers/software out there. As far as what harness to use then it depends on what, if any, emissions you want to keep and what tranny your running. If your using a th-350/400 or a manual then use a 99-up harness for a LS1 with a T56. If your planningon runnign a 4l60E then run a automatic harness. But yes, you will need a 4x2 harness since there is no transfer case to control. Just get a harness/computer out of a F-body.
Old 06-12-2006, 10:14 PM
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So far everything that was said was correct and very good info, except that you NEED a 2wd harness. You do not NEED a 2wd harness, either will work if you end up with a 4x4 harness you will just have a couple extra wires which you can eliminate. You can either use a f-body or truck harness and computer. Which intake manifold are you running? The truck and f-bodies use different injectors and coils. The injectors use a different electrical connector and so do the coils. For the injectors you would have to individually splice different connectors on if you use truck injectors and a f-body harness, for the coils I have heard that you can just plug either coil harness into either main harness. One last thought is that more people are familiar with the f-body harnesses and more pinouts/diagrams are available for free for those harnesses.
Old 06-13-2006, 08:19 AM
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I am going with the LS6 intake and a T56 trans for the swap. Also as far as the emissions go I am going to use any of that stuff, except if there are some that are required to make it run properly. Thanks for all the feedback!
Old 06-13-2006, 11:50 PM
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Then I would look for a 99-02 f-body 6 speed stick harness and computer. That should give you the least amount of alterations possible, just get some truck coil pack harnesses and they should plug into the f-body harness.
Old 06-14-2006, 04:08 PM
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I'm in a somewhat similar situation & G-Body has been a big help . I have an '03 5.3L truck motor that had a damaged harness w/ electronic throttle body. I picked up another truck harness and a damaged '98 F-body 6-speed harness pretty cheap.
The main wiring/plug differences I have found are as follows:

The injector plugs are different. Trucks use Motec 2 injectors, and the cars use the older style like on the LT1 (Bosch/Lucas etc.). I had to use an LS1 manifold (and rails) for clearance, so I got the car harness vs. clipping & re-wiring the injector plugs.

The alternator plug is different. The 1998 car has 1 small wire vs 3 for the truck. This changed for the cars in 1999 when the PCM controlled the alternator.

The coolant temp sensor in the head is different. A parts house shows the '98 sensor only fits 97-98 Vettes & 98 F-bodies, while the '03 truck sensor fits a 99-02 F-body. I don't know about the temp range or resistance of the sensor, but from reading the LS1 swap book, there is a terminal on the 99+ sensor that goes to the GM dash gauge & only works with GM gauges, so this may be OK for your '92 F-body (my swap is a Supra if you haven't figured that out from my username ).

I can't address EGR or AIR connectors since I will not be using those functions.

I am using Evap/MAP/MAF controls/sensors for the '98 motor so I can't advise on differences here.

The coil connectors and wiring colors appear to be the same.

I found that it is not difficult to add connector wiring at the PCM plug since my speed sensor wiring had been removed from the '98 harness at the plug. I took same colored wires w/ PCM connector from the damaged '03 harness and added them into the '98 harness.

In summary, you would be better off with a 99-02 F-body PCM for what you want to do.

EDIT
I went through the parts house website & found the crank & knock sensors were the only parts to be the same for a 98 car, 02 car, and 03 truck.

The inlet air temp, MAF, cam position, coolant, MAP, and O2 sensors all showed as being different between the 3.

On the cars, the only differences noted were the cam position & coolant sensors. This was an interesting find, as I thought all the cam sensors were the same.

Last edited by V8 Supra Builder; 06-14-2006 at 10:12 PM. Reason: Additional info
Old 06-14-2006, 08:17 PM
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Don't forget one other main wiring/plug difference... The 98 compared to the 99-up ECM pinouts are ENTIRELY different.
Old 06-14-2006, 10:12 PM
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Originally Posted by Jones'n
Don't forget one other main wiring/plug difference... The 98 compared to the 99-up ECM pinouts are ENTIRELY different.
Good point- I didn't realize this until I saw an actual 99 pinout in the sticky. I guess the GM LS1 swap book has a hybrid wiring pinout, as the C1/C2 connectors seem to follow the '98 harness very closely, yet it also has the three wire alternator setup like the 99+.

A whole lot of spaghetti here. I found that I can adapt the Toyota alternator wiring directly to the truck alternator, so I can stick with a '98 PCM since that is what the rest of the stuff I have is.
Old 06-14-2006, 11:16 PM
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now im really confused. i was originally planning on using a 99-02 fbody harness for my ls1 swap into my 94 z28. speartech told me to use a 98 harness and make sure i use a coolant temp sensor from a 98 car and then all my gauges would work fine?

should i start looking for a 99+ setup? i mean i should have my harness within the next few days....
Old 06-14-2006, 11:54 PM
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Originally Posted by 1bdbrd
should i start looking for a 99+ setup? i mean i should have my harness within the next few days....
What computer are you using? Using a 99+ computer with a 98 harness or vice versa requires a bunch of pins to be switched around.

Using a 98 temp sender would make it easy to hook up your temp gauge, and you could just switch over to a 98 temp sender connector on your 99+ harness.
Old 06-15-2006, 10:55 AM
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Old 06-15-2006, 02:49 PM
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Originally Posted by 1bdbrd
now im really confused. i was originally planning on using a 99-02 fbody harness for my ls1 swap into my 94 z28. speartech told me to use a 98 harness and make sure i use a coolant temp sensor from a 98 car and then all my gauges would work fine?

should i start looking for a 99+ setup? i mean i should have my harness within the next few days....
If you are who I think you are I told you to use the 98 F-body coolant temp sensor, not the 98 harness!!

I'm not a big fan of the 98 harness/PCM (although they work fine if it's what you already have to start with).
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Old 06-15-2006, 04:28 PM
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Originally Posted by Speartech
If you are who I think you are I told you to use the 98 F-body coolant temp sensor, not the 98 harness!!

I'm not a big fan of the 98 harness/PCM (although they work fine if it's what you already have to start with).
it is probably my mistake. for some strange reason i was under the impression i was to use both. no harm no foul as i was just trying to get a better understanding of this.
Old 06-15-2006, 04:38 PM
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Yeah, if you have a 99-02 harness definitely go with that and just add an extra wire for the 98 3-terminal coolant temp sensor.
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Old 06-15-2006, 04:59 PM
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im actually awaiting my 98 m6 harness. although im considering going with a 4l80e instead of a t56 now. ill talk to a friend tonight and see if he wants to buy my 98 harness so he can start collecting parts for his 3rd gen trans am ls1 swap that i know hell use an m6 in.
Old 08-10-2006, 11:48 AM
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Wright now I have a one wire alternator what would I have to do to make the 99ecm work with this alternator. If I understand the other post correctly the temp sensor can be wired to work. what about the cam sensor. By the way it is in a hybrid .

Last edited by 88s10; 09-27-2006 at 12:32 PM.
Old 08-10-2006, 12:16 PM
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if your got so many problems.. and using a mixture of engine / trans / accessories.. why not just go to Speartech or any of the other Vendors of Wiring harness, PCM and programming.. and just get a custom harness and PCM.. in the long run, you will be better off than trying to buy a harness that doesn't fit or work and then trying to modify it on top of the cost to buy and modify.

Than's my 2 cent's
Old 08-10-2006, 01:11 PM
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Originally Posted by bczee
if your got so many problems.. and using a mixture of engine / trans / accessories.. why not just go to Speartech or any of the other Vendors of Wiring harness, PCM and programming.. and just get a custom harness and PCM.. in the long run, you will be better off than trying to buy a harness that doesn't fit or work and then trying to modify it on top of the cost to buy and modify.

Than's my 2 cent's
Old 05-04-2007, 09:24 PM
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Originally Posted by bczee
if your got so many problems.. and using a mixture of engine / trans / accessories.. why not just go to Speartech or any of the other Vendors of Wiring harness, PCM and programming.. and just get a custom harness and PCM.. in the long run, you will be better off than trying to buy a harness that doesn't fit or work and then trying to modify it on top of the cost to buy and modify.

Than's my 2 cent's

sorry, i have to disagree with you.i have used a factory harness and 2 aftermarket harnesses and i would use a factory one anyday of the week over a made one. i think its easier.


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