When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Hello everyone, recently I bought I bunch of parts from a junkyard to 5 speed swap my 05 Civic. One of the parts I bought is a 5 speed ECU from an 04 Civic EX 5 speed. The part number is 37820-PLR-A12, which is correct for the 04-05 Civic VTEC 5 speed. I wanted to do my best to make sure the ECU is good before I pay to have it flashed. Can't start the engine, but I plugged the ECU in to see if it would communicate with my scanner. It does communicate and I am able to read temps, voltages, etc normally. The weird thing is that it's setting a P2647 code. Not only is that code not applicable to the D17 powered Civics (according to the dealer and other forums), but it's setting the code as soon as I turn the key on without even starting the engine. If I clear the code, it will stay off for about 5 seconds and come right back. I know that my VTEC solenoid and wiring is good since the car drives perfectly fine with the auto ECU and VTEC comes on as it should without setting any codes.
The only possible cause I can think of is I have a JDM D17A engine, which has no VTEC pressure switch. However, since to the best of my knowledge the pressure switch is normally open and closes when it detects pressure, I don't see how the ECU would even know that the switch isn't there since I never started the engine, therefore it wouldn't have seen oil pressure and the circuit would be open anyways.
Since that code seems to only be applicable to K series engines, the only other possibility I can think of is perhaps at some point someone put a K series ECU board in the stock housing. The car I got this ECU from had no motor or trans in it, so I don't know if it was K swapped. Seems unlikely, but that is the only other explanation I can think of. I took the cover off the ECU to look for signs that the board has been swapped or damaged and didn't see any, but there's no part number on the board so I have no way to know for sure.
If anyone has any other ideas of what could be going on here please let me know, I don't want to have the ECU flashed only to find out that it's bad. Thanks in advance, any input is greatly appreciated!
Sorry, perhaps I wasn't clear. I did not mean a performance reflash, I meant an immobilizer flash. USDM 7th gen ECU's needs to be flashed to the immobilizer and key before it will let the engine start. I do not want to pay to have this service performed if the ECU is defective.
The switch is closed with no pressure and opens when pressure is seen. If the D17A doesn't have this pressure switch then the ECU absolutely knows. It's seeing an open circuit (meaning sufficient oil pressure) with just ignition on and engine off which isn't possible.
The switch is closed with no pressure and opens when pressure is seen. If the D17A doesn't have this pressure switch then the ECU absolutely knows. It's seeing an open circuit (meaning sufficient oil pressure) with just ignition on and engine off which isn't possible.
Thank you for the information! The D17A does have that pressure switch for the warning light, what it does not have is the pressure switch on the VTEC solenoid. Is that switch also closed with no pressure? From what I can find my understanding was that the VTEC solenoid pressure switch is normally open and closes when pressure is seen, but I don't have one to test so I can't verify that.
I honestly don't even remember seeing the pressure sensor where a parts catalog is showing it, been a while since I've worked on a D17, but it does give a few steps on testing it. It says it should have continuity when the engine isn't running, normally closed. Don't understand why the D17A wouldn't have it.
Last edited by BrotatoChip; Mar 12, 2021 at 11:59 AM.
I honestly don't even remember seeing the pressure sensor where a parts catalog is showing it, been a while since I've worked on a D17, but it does give a few steps on testing it. It says it should have continuity when the engine isn't running, normally closed. Don't understand why the D17A wouldn't have it.
Cool, thank you for your help. I guess I could try grounding that pin with a test light and seeing if the code comes back. I'm not sure why the JDM engines don't have the pressure switch but none of them do that I know of, they just have a plug in the hole instead. My JDM K24A is the same way. Maybe US emissions regulations require verifying the functionality of the system or something, not sure.
The problem is if you're using a USDM ECU and don't wire up the pressure switch VTEC will never engage. That goes for the K24a as well unless there's an option in Kpro to ignore the VTEC oil pressure switch.
The problem is if you're using a USDM ECU and don't wire up the pressure switch VTEC will never engage. That goes for the K24a as well unless there's an option in Kpro to ignore the VTEC oil pressure switch.
Thank you for your help. The VTEC solenoid pressure switch must be normally closed because when I ground that pin on the ECU it doesn't set that code. Next time I am at the junkyard I will grab a pressure switch and wire it in since I will eventually need it to keep the USDM ECU happy. I'm glad I found that ECU because the 04-05 Civic 5 speed VTEC is not at all easy to find in junkyards, at least where I live.
