03 to 05 ECU swap - help getting started

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

SavedByGrace

Member
Joined
Dec 11, 2018
Posts
41
Reaction score
2
Location
California
Ram Year
2001
Engine
5.2 Laramie
Howdy all - ive read the thread here (https://www.ramforum.com/threads/03-to-05-pcm-swap.103201/ )

I have a 2003 2500 HD 5.7 and want to go ahead with the swap. Been considering selling it, but its our desert truck, ive since re-ringed the motor 5k miles back, swapped the TC, CAT, coils, new tires, suspension - everything works it just drives like a **** when im towing light stuff, wd hurt to see her go - so considering working with what I have for now.

I know I need a black key / non skim ECU from an 05, what connector from the 05 do I need as well? Or is it just a matter of swapping the 03 TCM wires into the C4 socket? Can someone just drop a bullet list perhaps to get me started? I have a hard time remembering stuff correctly from a mountain bike head injury few years back so excuse if i see a bit nubile here, it just really helps me cover things in point form. Planning on 4.1 or even 4.56 gears down the road.

Thanks!

Im tossing between a 4.1 or 4.56 gear swap, and possibly a stroker crank...
 
Last edited:
OP
OP
SavedByGrace

SavedByGrace

Member
Joined
Dec 11, 2018
Posts
41
Reaction score
2
Location
California
Ram Year
2001
Engine
5.2 Laramie

I think that guy went too far- he ripped everything apart.. another member posted that 03 to 05 is possible with just the ecu swap, 2 02 sensors and rewiring, i dont wanna rip my truck apart, just swap engine harness and repin the TCM to C4 plug - if i have my facts straight on that..
 
OP
OP
SavedByGrace

SavedByGrace

Member
Joined
Dec 11, 2018
Posts
41
Reaction score
2
Location
California
Ram Year
2001
Engine
5.2 Laramie
anyone? can this be done with just an 05 ecu and repin + 2 02 sensors (or delete)?
 

tron67j

Senior Member
Joined
Oct 14, 2019
Posts
4,105
Reaction score
5,425
Location
Maryland
Ram Year
2018
Engine
6.4 Hemi
I had a 2003 2500 5.7 and had an issue with an O2 sensor. Long story short is that the dealer determined that my set up was actually using the 2002 2500 5.9 sensor set up probably a leftover set of parts that they adjusted my ECU to accept. My point, you could end up with problems if your vehicle was near the beginning of production as my truck apparently was. Good luck.
 

jotin

Senior Member
Joined
Jun 7, 2016
Posts
429
Reaction score
193
Location
your mom
Ram Year
2003
Engine
5.7
anyone? can this be done with just an 05 ecu and repin + 2 02 sensors (or delete)?
I do these conversions a lot. Using the 03 harness. I repin the connector to the green trans connector for the 05. Add in the 02 sensor connectors and make sure it’s all working properly myself. I can help if needed.
 

Jgress77

Junior Member
Joined
Dec 15, 2021
Posts
27
Reaction score
3
Location
Missouri
Ram Year
2003
Engine
5.7
I do these conversions a lot. Using the 03 harness. I repin the connector to the green trans connector for the 05. Add in the 02 sensor connectors and make sure it’s all working properly myself. I can help if needed.
Id love it if you could help me with this swap as im trying to boost my hemi
 

RamDiver

Senior Member
Joined
Jan 23, 2022
Posts
5,759
Reaction score
12,153
Location
Marlborough, Ontario Canada
Ram Year
2021 DS
Engine
Hemi 5.7
I do these conversions a lot. Using the 03 harness. I repin the connector to the green trans connector for the 05. Add in the 02 sensor connectors and make sure it’s all working properly myself. I can help if needed.

The OP hasn't been online here in about 1.5 years.

last seen.jpg


There is another interested party to assist. :cool:


Id love it if you could help me with this swap as im trying to boost my hemi

.
 

Forum statistics

Threads
211,381
Posts
3,065,838
Members
171,790
Latest member
ChloeBrooks
Back
Top