Hondata

Hi, looking for some advice. K24 engine 6 speed trans, hondata kpro v4 37820-PRC-023, having issue with the alternate a/c input. I have set in misc use vtp switch as alternate a/c input. But it does not work at all. What could be the problem.

How do you have this input wired?

After enable vtpsw as alternate a/c input. Started the engine applied gnd to pin b9. Used a test light to see if e18 has output, but nothing. Also noticed that idle did not compensate for a/c.

Do you see the VTP input registering the input on the sensor list?

No I don't see it. I have downloaded a hondata app. Ac does not turn on from the list.

Post the calibration and a datalog showing the issue.

Also post a diagram of exactly how you have this wired.

Spunkster wrote: Mon Nov 10, 2025 5:16 pm Do you see the VTP input registering the input on the sensor list?

yes i see this, after checking VTP is ON state, while nothing is connected on b9 pin. also noticed the FANC is also in ON state, nothing connected on B6 pin.

As for the diagram i simply connected b9 to ground just to test. so wires are not really connected to anything yet.

i haved attaced the calibration and datalog files.

Hi, was wondering if there is something wrong with my replies ?
I would like to add a little history about the car I'm working on. It was sent to us because the owner is confused about the a/c wiring. So this is the 2nd k24 with hondata ECU we have fixed. The first car we set the vtp as alternate input a/c and fixed the a/c wiring and all went well. But with this 2nd one. Was hoping to get same results but not acting the way ita supposed to.

Came here to see if someone might be able to help.

Thanks

additonal info.

honda k-pro v4
honda ek3

hondata serial number 40513
37820-PRC-023

i think i have found the answer to my quesiton. if anyone can confirm this. So the PRC ECU does not have the vtp circuitry hence the alternate a/c input will not work?

That is correct. Sorry was away last week.