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I just purchased a project truck. It’s a 2004 Single cab step side Silverado. It was a V6. It now has a 2001 5.3 with harness and ECU bolted in but not connected. Previous owner replaced drive by wire with drive by cable.
I’ve been plugging the harness connections to the engine. Everything is fitting but it looks like two large connections near the under hood fuse block are not going too match up.
Should the 2001 harness connect to the 2004 truck?
If not what needs to be changed?
I believe you need a 03-07 V8 harness and ECM. You have the ECM, the V6 works and you just need to tune it.
If someone can confirm what I said is true because I don't want to sell you short. I actually have a 2004 V8 engine harness I'd be willing to part ways with
I believe you need a 03-07 V8 harness and ECM. You have the ECM, the V6 works and you just need to tune it.
If someone can confirm what I said is true because I don't want to sell you short. I actually have a 2004 V8 engine harness I'd be willing to part ways with
Correct 03+ harness with the Green/Blue connectors.
I don't think the previous owner swapped from DBW to DBC... IIRC all the GMT-800 six cylinder trucks are DBC. You'll need a PCM with the IAC (idle air control) chip for a DBC setup. All P01 (0411) PCM's have the IAC chip and some P59 PCM's have the IAC chip. You can open the P59 and see if it has the IAC chip.
Thank you for your responses. I have been doing lots of reading and really confused myself. I was thinking I was going to have to change reluctor wheels and drill and tap for knock sensors. Definitely an info overload.
I found the LT1swap.com web site and got lots of info on harnesses and PCMs. I see my PCM is from the V6 and will work with the DBC.
The harness I have is from the 5.3.
All of the connections/plugs on the engine wiring harness are mating to the engine. The only thing I have found different is the connector/plug from the engine harness to the body harness that goes down the frame rail to the back of the truck. I assume for fuel pump and lights, I didn’t trace it out.
All of the wires in the two connections are the same colors, just different type connectors. One is flat, wide and blue. the other is rectangular and white and blue.
I went to Pull a Part and got a matching male connection and will be repinning it.
I plan to send my PCM to someone be programmed.
what would be the difference in the 99-02 and 03 up harness?
Is it just the addition of the IAC?
11-17-2021, 09:31 PM
2001 5.3LM7 in a 2004 Silverado
