Engine wiring upgrade - 2003 5.7 to 2004/2005
#21
01-07-2014, 04:00 PM
I thought I would upgrade my wiring and pcm to 2004/2005. I eventually want to put a camshaft in that will require custom tuning and I didn't want to run into any of the 2003 tuning issues. And since the combination of diablosport/superchips screwed my 2003 pcm, I went forward with the project.
After comparing the pinouts I picked up a 2004 pcm and harness. I didn't realize how differently they are setup, as C3 (white plug) is on a separate harness.
Basically, 3 of 4 pcm plugs are almost identical. The differences are that 2004/2005 has pins for EGR and 2 extra O2 sensors (1 pre-cat, 1 post-cat). The 4th plug (green) contains the transmission stuff so that one is the biggest difference. Since I have a 2002, I had to redo some of the wiring I did before to retrofit 2002 to 2003. There are some other little differences as well.
I ended up removing the green plug wiring and TCM wiring from the 2003 harness and replacing it with the green plug wiring I extracted from the 2004 harness. Now I have a decent looking 2003 harness with the big C130 dash plug and all but with the extra stuff for 2004/2005. I'll probably pick up a 2005 pcm when I can find one cheap just to try out the diablo trans stuff but I'm going manual anyway. The service manuals show 2004 and 2005 being exactly the same.
Now that I'm really familiar with the wiring, I would not do it this way again. I would just pick up 2 O2 plugs and run fresh wires for those. Then remove TCM and rewire to C4 (green plug) accordingly since I have a lot of extra pcm pins and wires.
I soldered a $hitload of wires so it was a decent project, but sure as hell beats dealing with future tuning issues and it was done inside on a workbench. Everything still works, I just have 2 EGR codes (will be removed with custom tune) and a code for the 2nd downstream O2 sensor that I will eventually add when I put cats in. I now have an extra 2003 harness so I'm going to make another one and sell it off if anyone is interested. Let me know if you're trying to tackle this and have any questions.
From 2004 harness separated and labeled
TCM and C4 stuff removed from 2003 harness
Putting it all together
Open PCM plug and remove tab to insert new wire
Adding a PCM wire
Edit: Don't do it this way. You can yank/insert wires from the back without removing the face of the plug.
Harness boxed up again - Left side - 2004 style
Right side - original 2003 style
After comparing the pinouts I picked up a 2004 pcm and harness. I didn't realize how differently they are setup, as C3 (white plug) is on a separate harness.
Basically, 3 of 4 pcm plugs are almost identical. The differences are that 2004/2005 has pins for EGR and 2 extra O2 sensors (1 pre-cat, 1 post-cat). The 4th plug (green) contains the transmission stuff so that one is the biggest difference. Since I have a 2002, I had to redo some of the wiring I did before to retrofit 2002 to 2003. There are some other little differences as well.
I ended up removing the green plug wiring and TCM wiring from the 2003 harness and replacing it with the green plug wiring I extracted from the 2004 harness. Now I have a decent looking 2003 harness with the big C130 dash plug and all but with the extra stuff for 2004/2005. I'll probably pick up a 2005 pcm when I can find one cheap just to try out the diablo trans stuff but I'm going manual anyway. The service manuals show 2004 and 2005 being exactly the same.
Now that I'm really familiar with the wiring, I would not do it this way again. I would just pick up 2 O2 plugs and run fresh wires for those. Then remove TCM and rewire to C4 (green plug) accordingly since I have a lot of extra pcm pins and wires.
I soldered a $hitload of wires so it was a decent project, but sure as hell beats dealing with future tuning issues and it was done inside on a workbench. Everything still works, I just have 2 EGR codes (will be removed with custom tune) and a code for the 2nd downstream O2 sensor that I will eventually add when I put cats in. I now have an extra 2003 harness so I'm going to make another one and sell it off if anyone is interested. Let me know if you're trying to tackle this and have any questions.
From 2004 harness separated and labeled
TCM and C4 stuff removed from 2003 harness
Putting it all together
Open PCM plug and remove tab to insert new wire
Adding a PCM wire
Edit: Don't do it this way. You can yank/insert wires from the back without removing the face of the plug.
Harness boxed up again - Left side - 2004 style
Right side - original 2003 style
Pat
#22
01-08-2014, 05:19 PM
Registered User
You only need a PCM from the 2005, preferably a 2500 model so that the egr valve is not an issue. The wires and plugs are all there. Just get two more o2 censors and go for it. Diablosport shows that they have way more tuning adjustment ability with the handheld on a 2005. Shift firmness, and a bunch of other stuff. Look it up and do the comparison of the 04 to the 05. There is a place in the Miami area that sells the PCM off the shelf for around $130, and they can do the egr delete for you, give you the correct vin number, and more, it might be worth a look. I found them on eBay and called them. I am finally going to get to my wiring harness, my truck had a bad injector which leaned out cylinder 3 and broke the piston. So I have been playing catch up, paying down another credit card... At least work has been picking up.
Last edited by DanielHemi; 01-08-2014 at 05:33 PM. Reason: Wrong info
#23
01-09-2014, 09:28 AM
You only need a PCM from the 2005, preferably a 2500 model so that the egr valve is not an issue. The wires and plugs are all there. Just get two more o2 censors and go for it. Diablosport shows that they have way more tuning adjustment ability with the handheld on a 2005. Shift firmness, and a bunch of other stuff. Look it up and do the comparison of the 04 to the 05. There is a place in the Miami area that sells the PCM off the shelf for around $130, and they can do the egr delete for you, give you the correct vin number, and more, it might be worth a look. I found them on eBay and called them. I am finally going to get to my wiring harness, my truck had a bad injector which leaned out cylinder 3 and broke the piston. So I have been playing catch up, paying down another credit card... At least work has been picking up.
Thank you for the reply! And do you have 4 wheel abs, I do will that be a factor in the 05 PCM? And I don't need any of the harness off of a 05?
#24
01-09-2014, 12:42 PM
Banned
#25
01-09-2014, 08:49 PM
Registered User
#26
01-09-2014, 09:17 PM
Banned
The abs is not an issue, it runs off a different computer. I always thought that the four wheel abs was standard on these models. It was on mine. And no, you don't need another harness. Just patience and wires for the extra o2 censors and the stuff t-muns listed. Good times!
#27
01-09-2014, 11:19 PM
The abs is not an issue, it runs off a different computer. I always thought that the four wheel abs was standard on these models. It was on mine. And no, you don't need another harness. Just patience and wires for the extra o2 censors and the stuff t-muns listed. Good times!
#28
01-15-2014, 05:45 PM
You only need a PCM from the 2005, preferably a 2500 model so that the egr valve is not an issue. The wires and plugs are all there. Just get two more o2 censors and go for it. Diablosport shows that they have way more tuning adjustment ability with the handheld on a 2005. Shift firmness, and a bunch of other stuff. Look it up and do the comparison of the 04 to the 05. There is a place in the Miami area that sells the PCM off the shelf for around $130, and they can do the egr delete for you, give you the correct vin number, and more, it might be worth a look. I found them on eBay and called them. I am finally going to get to my wiring harness, my truck had a bad injector which leaned out cylinder 3 and broke the piston. So I have been playing catch up, paying down another credit card... At least work has been picking up.
#30
06-24-2019, 07:47 PM
Need help converting 03 harness to 05
I thought I would upgrade my wiring and pcm to 2004/2005. I eventually want to put a camshaft in that will require custom tuning and I didn't want to run into any of the 2003 tuning issues. And since the combination of diablosport/superchips screwed my 2003 pcm, I went forward with the project.
After comparing the pinouts I picked up a 2004 pcm and harness. I didn't realize how differently they are setup, as C3 (white plug) is on a separate harness.
Basically, 3 of 4 pcm plugs are almost identical. The differences are that 2004/2005 has pins for EGR and 2 extra O2 sensors (1 pre-cat, 1 post-cat). The 4th plug (green) contains the transmission stuff so that one is the biggest difference. Since I have a 2002, I had to redo some of the wiring I did before to retrofit 2002 to 2003. There are some other little differences as well.
I ended up removing the green plug wiring and TCM wiring from the 2003 harness and replacing it with the green plug wiring I extracted from the 2004 harness. Now I have a decent looking 2003 harness with the big C130 dash plug and all but with the extra stuff for 2004/2005. I'll probably pick up a 2005 pcm when I can find one cheap just to try out the diablo trans stuff but I'm going manual anyway. The service manuals show 2004 and 2005 being exactly the same.
Now that I'm really familiar with the wiring, I would not do it this way again. I would just pick up 2 O2 plugs and run fresh wires for those. Then remove TCM and rewire to C4 (green plug) accordingly since I have a lot of extra pcm pins and wires.
I soldered a $hitload of wires so it was a decent project, but sure as hell beats dealing with future tuning issues and it was done inside on a workbench. Everything still works, I just have 2 EGR codes (will be removed with custom tune) and a code for the 2nd downstream O2 sensor that I will eventually add when I put cats in. I now have an extra 2003 harness so I'm going to make another one and sell it off if anyone is interested. Let me know if you're trying to tackle this and have any questions.
From 2004 harness separated and labeled
Attachment 56264
TCM and C4 stuff removed from 2003 harness
Attachment 56265
Putting it all together
Attachment 56266
Open PCM plug and remove tab to insert new wire
Attachment 56267
Adding a PCM wire
Edit: Don't do it this way. You can yank/insert wires from the back without removing the face of the plug.
Attachment 56268
Harness boxed up again - Left side - 2004 style
Attachment 56269
Right side - original 2003 style
Attachment 56270
After comparing the pinouts I picked up a 2004 pcm and harness. I didn't realize how differently they are setup, as C3 (white plug) is on a separate harness.
Basically, 3 of 4 pcm plugs are almost identical. The differences are that 2004/2005 has pins for EGR and 2 extra O2 sensors (1 pre-cat, 1 post-cat). The 4th plug (green) contains the transmission stuff so that one is the biggest difference. Since I have a 2002, I had to redo some of the wiring I did before to retrofit 2002 to 2003. There are some other little differences as well.
I ended up removing the green plug wiring and TCM wiring from the 2003 harness and replacing it with the green plug wiring I extracted from the 2004 harness. Now I have a decent looking 2003 harness with the big C130 dash plug and all but with the extra stuff for 2004/2005. I'll probably pick up a 2005 pcm when I can find one cheap just to try out the diablo trans stuff but I'm going manual anyway. The service manuals show 2004 and 2005 being exactly the same.
Now that I'm really familiar with the wiring, I would not do it this way again. I would just pick up 2 O2 plugs and run fresh wires for those. Then remove TCM and rewire to C4 (green plug) accordingly since I have a lot of extra pcm pins and wires.
I soldered a $hitload of wires so it was a decent project, but sure as hell beats dealing with future tuning issues and it was done inside on a workbench. Everything still works, I just have 2 EGR codes (will be removed with custom tune) and a code for the 2nd downstream O2 sensor that I will eventually add when I put cats in. I now have an extra 2003 harness so I'm going to make another one and sell it off if anyone is interested. Let me know if you're trying to tackle this and have any questions.
From 2004 harness separated and labeled
Attachment 56264
TCM and C4 stuff removed from 2003 harness
Attachment 56265
Putting it all together
Attachment 56266
Open PCM plug and remove tab to insert new wire
Attachment 56267
Adding a PCM wire
Edit: Don't do it this way. You can yank/insert wires from the back without removing the face of the plug.
Attachment 56268
Harness boxed up again - Left side - 2004 style
Attachment 56269
Right side - original 2003 style
Attachment 56270