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RSX K20a2 VSS Issue (CRV ECU?)

Posted: Mon Jul 21, 2025 10:36 am
by bryantr
So I bought a Kpro v4 with a used ECU since my car is my daily and had to wait for shipping. The ECU turned out to be a 37820 PPA A25 which is for CRV's which I would assume the reasoning my VSS and Vtec stopped working. I own a 2003 RSX Type S stock harness everywhere. Is there anyway i can fix this issue and not having to spend more money on a new kpro ? maybe wire something to this ECU that I received? Thank you in advance!

Re: RSX K20a2 VSS Issue (CRV ECU?)

Posted: Mon Jul 21, 2025 10:50 am
by Spunkster
The PPA-A25 is not compatible with K-Pro.

Re: RSX K20a2 VSS Issue (CRV ECU?)

Posted: Mon Jul 21, 2025 11:16 am
by bryantr
im a rookie with tuning, what specifically isnt compatible? I have the ECU installed and the minor tweaks like launch control and burble tune seem to be working properly and other modifications work. Its only the VSS that doesnt read. It came with extra wiring with 10 different colors but I have no clue what its used for and was thinking maybe it'll fix if i wire a specific color to the ecu onto my harness. Maybe a picture of the ECU can help ?

Re: RSX K20a2 VSS Issue (CRV ECU?)

Posted: Mon Jul 21, 2025 12:00 pm
by bryantr
this is how the PPA ECU is looking like

Re: RSX K20a2 VSS Issue (CRV ECU?)

Posted: Mon Jul 21, 2025 12:42 pm
by Spunkster
You said PPA-A25, and that ECU is a PPA-A52 which is an automatic. Details on using an auto ECU can be found at: https://hondata.com/tech-alternative-ecu-engine-swap

Re: RSX K20a2 VSS Issue (CRV ECU?)

Posted: Tue Jul 29, 2025 8:57 am
by bryantr
I just finished wiring to a18, alt speed input kpro v4 calibration is set to 108000 default, is that fine to run or do i have to change that number ?

Re: RSX K20a2 VSS Issue (CRV ECU?)

Posted: Tue Jul 29, 2025 9:15 am
by bryantr
Also, is the A18 wire supposed to be plugged back into the dark grey ecu plug to get VSS to work or do i leave A18 unplugged while both A18 and Red Wire being connected ?

Re: RSX K20a2 VSS Issue (CRV ECU?)

Posted: Tue Jul 29, 2025 11:12 am
by Spunkster
So did you connect the wire from A18 to the input on the K-Pro board?

Have you datalogged to see if it reads the speed. IF it does you may need to adjust the number of pulses per mile to make it more accurate.

Re: RSX K20a2 VSS Issue (CRV ECU?)

Posted: Tue Jul 29, 2025 11:43 am
by bryantr
This is how i currently have it set up. haven’t heat shrinked it (wanted to make sure it worked before i did that) It did end up fixing my VSS and it reads it now and doesn’t stay at 0 , but i still can’t manage to get VTEC to engage.

VTEC Solenoid is good
Oil is good
Doesn’t throw P0500 code on dash no more

Speed Sensor is set to Alt Speed Input
Calibration: 2485 pulses per km (Smoothing 10)

VTEC Window:
Lower Boundary: went to 4200 rpms / kept 90 kPa (which was default)
Upper Boundary: went to 4500 rpms / kept 24 kPa (also default)

VTEC oil pressure switch enabled