Hondata

G'day.
Currently own a p28 s300. Unfortunately it seems when I try set my fan over ride protection ( lower temperature) the car won't respond to it. Is there anything specific I have to put in place to make this function work ? Or are the some p28 versions that don't support this ?

Thanks

What vehicle is this in?

94 honda civic hatchback

Have you checked to see if the wire from the ECU actually goes to the fan relay? IF your car does not have this wire or if the wire does not go to it then it will not work until you wire it in properly.

where is the fan relay located? and what is the pinout from a p28 obd1 ecu?

You will need to look at the Factory service manual (Helms) to help you find these things. The ETM (electrical troubleshooting manual) may also be helpful.

http://www.hondata.com/help/smanager/ecuconnectors.htm

I also have this problem, my harness is OBD2B so my FANC wire should be A20 on my harness according to your ECU output diagram...I am running an aftermarket SPAL fan using an aftermarket relay that came with the fan via T1race developement, my fan cuts in, and out at the factory pre-set temps and is wired up correctly...I had to end up using a jumper wire on the thermostat fan switch plug to keep the fan running at all times over this summer cause I couldnt get this feature to work properly in the S300. I have the Haynes manual, which is the same as the Helmes with all the wiring diagrams....My stock fan worked fine before I did all this stuff to my car and the factory fan relays are all in place in the fusebox under the hood. Is there a wire I am missing here that I have to run from the aftermarket relay to the ECU or is there a simpler way?? Thanks...

The Haynes manuals are not the same as a Helms manual.

You need to trace the wire from the ECU to the fan relays. The fans should work on their own indepandant of the ECU using the fan thermoswitch. You have made changes to the wiring and need to check all that wiring. If you are still unsure how to check al this, take the car to a shop that has experience troubleshooting wiring related problems.

ok, will download the helmes manual....thanks...so the fan relays are in the fusebox under the hood if I am not mistaken, I can do that easy enough...The wiring on my car is the same harness that came with the car, 2000 civic si
(canadian), so all had to do in swapping the H22 was modify the harness a bit by extending a few sensor plugs to fit...but thats it...

I've had a similar problem with my p28 s300. I am running a rywire harness adapter, and the wire that controls the fan is loose. If you have the SManager open, add the FANC as a new indicator on your display. It should turn red when the ecu wants the fan to come on. At that point you should put a test light on the fan control wire coming from the ecu, and see if it is getting power. My wire was not, but my OEM fan switch on the motor still kicked the fan on. I ended up remounting the ecu and jiggling the wire a little, and the temporary fix works fine. There are numerous ecu pinout diagrams on the interwebs to figure out what wire it is on the harness for the fan control. Good luck.