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Hello everyone, I am in the process of buying the parts I need to K swap my Honda Civic ES1 and I am wondering which engine harnesses I can use. Where I live there are not many Hondas or Acuras and there are even fewer in the junkyards, so my options for parts are a bit limited. In the 4 years I lived here I have seen about 3 RSX's and 2 Civic EP3's and exactly zero in any junkyards, so my options for parts are a bit limited.

Right now I am looking for an engine harness for my K24A2 TSX motor. I am wondering if I can use a harness from an 03-07 Accord or a CRV or Element since those are the cars I can actually get an engine harness from around here. I know that the CRV harness can be used at least for a K24A1 swap with the CRV ECU since I have read about a couple people doing it, but I am not sure if that would work for a K24A2 swap. Not sure about the Accord harness, I can't find a decent picture of what connectors it has on it. I know it will connect to everything on the motor and plug into a regular K series ECU, but whether it has the same pinout and same kind of plug for the dash harness I have no idea.

I know people usually use the 02-04 RSX or EP3 harness for this swap, but as I said I can not get those harnesses locally and they are very expensive on eBay so I would really rather not buy one unless absolutely necessary as that would use up a significant chunk of the money I have saved up towards this swap, so if I can get away with a cheaper harness I would much rather go that route. If I have to repin some connectors or something to make it work that's fine, I just need something that works for as cheap as possible.

Thanks in advance as always, any info is greatly appreciated! :)
 

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Arouse the DAMPFHAMMER!
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I know people usually use the 02-04 RSX or EP3 harness for this swap, but as I said I can not get those harnesses locally and they are very expensive on eBay so I would really rather not buy one unless absolutely necessary as that would use up a significant chunk of the money I have saved up towards this swap, so if I can get away with a cheaper harness I would much rather go that route. If I have to repin some connectors or something to make it work that's fine, I just need something that works for as cheap as possible.
You can use the RBB harness of the K24A2 and rearrange, if necessary, it for the PRB ECU or go the FPro way Hondata FlashPro TSX 2004-2006 with CAN adapter harness, which would be an easier way as you may have already the DBW TB harness and ECU.
 

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Discussion Starter #4
You can use the RBB harness of the K24A2 and rearrange, if necessary, it for the PRB ECU or go the FPro way Hondata FlashPro TSX 2004-2006 with CAN adapter harness, which would be an easier way as you may have already the DBW TB harness and ECU.
Cool, thank you. A few problems with that plan though:

1. From the pics I can find online, it doesn't look like the TSX harness has the C101 connector that plugs into the dash harness. But please correct me if I am wrong

2. The TSX harness has the plug for an electronic throttle body instead of a TPS and IACV, but that shouldn't be too hard to change.

3. I don't know that I could even find a TSX harness locally, not many TSX's around here. And if I could find one it would almost certainly be from an automatic, not sure if that would be a problem?
 

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Awesome, thanks! I may be able to make that work then. My K24 came with the engine harness and most of the charge harness but the part that goes through the firewall has been cut off and the part that went to the automatic trans was cut off, but I think that's it. I have an extra junk Civic engine harness that I can take the ECU part from, so maybe I can solder the wires together and make one usable harness out of 2 junk harnesses. As tempting as the free option is though, I'm not too crazy about adding so many points of failure since I need this car to be reliable.

EP3 harnesses seem to be a bit more reasonably priced, would there be any issues using one of those for my swap if I get an EP3 ECU with Kpro? Thanks
 

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Arouse the DAMPFHAMMER!
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...EP3 harnesses seem to be a bit more reasonably priced, would there be any issues using one of those for my swap if I get an EP3 ECU with Kpro? Thanks
The EP3 ECU, which is a EDM ECU = narrow band ECU, need a modification to run the wideband. Not recommendable. You can buy a PRB ECU (= wideband ECU) and use the EP3 harness, this is what I've did on my Lotus before I bought an RSX harness and an AEM Infinity.
 

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Discussion Starter #8
The EP3 ECU, which is a EDM ECU = narrow band ECU, need a modification to run the wideband. Not recommendable. You can buy a PRB ECU (= wideband ECU) and use the EP3 harness, this is what I've did on my Lotus before I bought an RSX harness and an AEM Infinity.
Interesting. Here in America all K series engines have a wideband o2 sensor, including the EP3. But the EP3 ECU's can be had for $250-$300 while the PRB ECU's don't sell for under $500. Since both ECUs support wideband o2 sensor and I am going to need KPro anyways, is there any reason to spend the extra $200+ for the RSX-S ECU? Thanks
o2 sensor.PNG
 

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Reverse lockout will only work with the Type S ECU, that's only relevant with a 6 speed transmission (not sure which you're using). You may have to check the pinout if not using a matching harness but other than that I don't think there's really any other difference once Kpro'd.
 

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Discussion Starter #10
Reverse lockout will only work with the Type S ECU, that's only relevant with a 6 speed transmission (not sure which you're using). You may have to check the pinout if not using a matching harness but other than that I don't think there's really any other difference once Kpro'd.
Thank you! Not sure what trans I am gonna use yet, that will be determined by which one I can find cheap. But either way no reverse lockout is not a deal breaker for me, if I end up getting a 6 speed either now or in the future I can always wire up an interlock button that must be pushed for reverse to engage.
 

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Interesting. Here in America all K series engines have a wideband o2 sensor, including the EP3. But the EP3 ECU's can be had for $250-$300 while the PRB ECU's don't sell for under $500. Since both ECUs support wideband o2 sensor and I am going to need KPro anyways, is there any reason to spend the extra $200+ for the RSX-S ECU? Thanks View attachment 103473
The difference is the PRB supports the 6 speed functions and the ep3 ecu does not. If I’m not mistaken.
 

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Discussion Starter #12
The difference is the PRB supports the 6 speed functions and the ep3 ecu does not. If I’m not mistaken.
Thank you. What 6 speed functions does it not support other than reverse lockout? I believe I can manually enter the gear ratios with Kpro anyways? And I'm not sure much would be effected if I couldn't with a manual trans.
 

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Discussion Starter #18
Cool, so I may not need to wire an interlock button if I get a 6 speed then.
 
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