Hondata

Hey guys

So I've been having issues with FANC not working on my 1999 Prelude. I traced wiring and found them to be all good. I'm running obd1 P72 with s300 v3. Eventually I swapped ecu with another vehicle (p28 with s300) and re-tested the operation. The fans now working when activated via s300.

Is the p72 ecu even capable of doing the FANC?

I even took it swapped s300 out of each ecu and swapped them over as well. The p28 works with the V3 unit.

I have a JDM P72 with s300 V1/version 2.3.3.0 and the FANC works fine.

Perhaps your P72 is damaged and that is why it is not working. A working P72 should function with FANC without any issues.

^^

Theres gotta be something I'm missing. I just took another virgin p72 obd1 and had the s300 installed with boost control
options. Once again, when activating the FANC output, the fans will not turn on.

I use a P72 in an 88 Integra with B18c5 swap and fan control works perfectly.

Are you saying you tried a P28 ecu in the same vehicle with the P72 and it worked?

^^ Yes

Originally I had a p72 and was not able to control the fans. Installed p28 and it worked. Found another Virgin p72 and had
the s300 installed and still was unable to control the fans.

Vehicle is a 1999 Prelude. All ecu's are USDM.