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
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TCM and C4 stuff removed from 2003 harness
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Putting it all together
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Open PCM plug and remove tab to insert new wire
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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.
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Harness boxed up again - Left side - 2004 style
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Right side - original 2003 style
wiring9.jpg?t=1330489401

 

<<<<Interested. How much? By the way, damn good job if the only CEL you have is for EGR. I have an 05 PCM and part of the harness (I have to look to see which part) already. You should publish a comprehensive parts list for the rest of us mere mortals.

 

Thanks. Not sure how much yet. The harness itself was $100. I'll see how this next one goes and then maybe you can make me an offer? I think it will be quite reasonable considering the nature of the job....just so I can make a little mod money

The following are the codes that I have. The speed controls are not CELs and I didn't know that I had them until I used the DSP. They are related to my 2002 conversion anyway. Edit: I forgot I still need to hookup a cruise wire since the new harness. That should take care of the cruise codes.
P0406 - EGR POSITION SENSOR HIGH
P0038 - O2 SENSOR 1/2 HEATER CIRCUIT HIGH
P0585 - SPEED CONTROL SWITCH NO.1 AND NO.2 CORRELATION
P0593 - SPEED CONTROL SWITCH NO.2 HIGH
P0403 - EGR CONTROL CIRCUIT

I took good notes but maybe I will write up more of a how-to after I do this one. Another thing I'll mention is that I have long tubes so I just bought another front O2 sensor and popped it in. Otherwise, need 2 O2 sensor connectors (1 up, 1 down), wire, solder, heat shrink tubing, conduit, tape. I wired up the EGR connector with the thought of mounting an EGR valve somewhere and plugging it in. I bought one but haven't tried plugging it in yet. I'm not totally convinced I can fool the PCM by just plugging in the EGR but it's worth a try. Custom tune or possibly a 2500 PCM would prob work anyway.

And another thing...My abs light is blinking and dinging. This happened when I initially swapped from 02 4.7 to 03 5.7. Once I reset my tire size with superchips it went away. Tried resetting tires with DSP and it didn't help. I don't have any front wheel speed sensors so I don't know for sure if the PCM I got had 4wheel abs or what. I figure my left wheel bearing has to go at some point...when it does, I'll replace with the hub that has a sensor port, etc.

 

Great pics and certainly a lot of work that seemed to have paid off

 

Set tire size with superchips and abs light gone now.

 

Damn nice undertaking of a project !!! good work dude . I am guessing you had some good wiring prints to work with man they make things easyer don't they

 

Thanks! The factory service manuals are fantastic...they really make anything like this possible.

Update: Popped in a 2005 PCM from a 2500 truck and EGR codes gone. Now the only CEL I have is for the 2nd downstream O2(P0038 - O2 SENSOR 1/2 HEATER CIRCUIT HIGH) so maybe I'll pick up a sensor tomorrow to be CEL-FREE again . Although the infinity amplifier is beeping at me after I start the truck. I guess I'll figure that out sooner or later.

I was also able to install a DSP performance tune and the transmission tunes as well. Pretty sweet.

 

Nice...do the 2500's not have EGR?

 

To my knowledge, no they do not have one.

 

Ah man, Maryland? Right next-door would be better. I am thinking of evetually putting a full 5.7 computer and wiring into this truck, but for now the 4.7 pcm is going to run my hemi with a custom tune, and later this year when the swap is done, I will see how well.

Nice job by the way.