onefast2gdsm

I put a 3g ecu flashed with tephramods v7 in my 98 gsx. Everything is working awesome, except my fans arent working. I checked the wiring, everything is wired correctly. The fans were working on my 2g reflashable ecu so i know they work. I also swapped relays and messed with the fan table in ecuflash with no luck. Here is how my ecu is wired

Swap pins 8 and 22.

Remove pin 20 (green/orange) and put in slot 32

Remove pin 21 (green/black) and put in slot 34

Remove pin 16 (red/black)

Remove pin 39

Remove pin 42

Remove pin 43 (Automatic Transmission only)

Remove pin 48 (Automatic Transmission on stock ECU but on EVO 8 ECU, it's fuel level. No use on a DSM so remove it.)

Remove pin 58 (white)

Remove pin 87 (yellow/red)

Remove pin 91 (Automatic Transmission only) (black)

onefast2gdsm

update: moved pin 32 topin 21. fans kick on with key on engine off, but with key on engine running it doesnt activate the fans.

phizzalot

iTrader: (3)

I had a very similar issue with installing an evo 8 /3g Eclipse Ecu into a 7g DSM Galant... which is very similar to a 2g..

I found out that the Evo and 3g Eclipse have a relay/solenoid on the actual fan which tells the fans to kick on and off. If that relay isn't there or malfunctions, then the fans just stays on when engine is on and off when key is off present.

My fans turn on and stays on when engine is on.

onefast2gdsm

the relays are all there and the fans worked with no issues on the 2g ecu.

Ive seen some pinouts saying 32&34 are a/c pinouts and others saying 31&32 are a/c pinouts on the evo ecu, I cant figure out which pins are correct. With pin 20 from the eclipse wiring connected to pin 21 on the EVO ecu, the fans are on with the key on engine off, but as soon as i start the car they turn off, with pins 20&21 from the eclipse wired to pins 32&34 on the EVO ecu, the fans dont kick on at all. I havent tried pin 31 yet.

gsrboi80

iTrader: (38)

Pins 31-32 are AC on the USDM EVO VIII 03-04 ecu

onefast2gdsm

just tried pin 31&32. still no luck. Id like to figure this out I really dont want to wire them to a switch.

4b11slayer

What if you check all pins to ecu with test light to see what has voltage and what doesnt.

Then let car get to temp and see if theres one that didnt have power now have power. Or maybe you can jump the temp sensor and then look for the voltage at the ecu?

onefast2gdsm

Are the a/c relay pins supposed to have 12v power all the time when engine is running?

4b11slayer

A relay usually has constant voltage,

onefast2gdsm

jumped rad fan hi relay pin 1 to ground, fans turn on. So apprentley i have power at the ecu, at the relay, but its not grounding to activate the relay for some reason.

4b11slayer

Its probably ecu ground controlled.

wreckleford

iTrader: (2)

Pins 32 and 34 are the AC fan control on the 8 ecu. It's erroneously stated as 31 and 32 several places on the net. I have verified this in the OEM service manual and have converted over 20 cars to Evo8 ECUs. IDK about the 3g ECU however. Maybe they are different.

Connect the fan wires to 32 and 34 and use Evoscan to trigger then to confirm if they are working or not. If they are not coming on I would ground each wire temporarily and see if the fan comes on (ignition must be on). If it does come on then you have an issue with the ECU , if not then you have a fuse/relay issue.

silver2gst

Please see the first post in the link below. I was the person that actually made the original table you see at the end of the post and my fans work from the AC output. You can see what pins need to be swapped with that table.

http://www.dsmtuners.com/threads/evo...-works.321515/

Please note, the primary fan outputs on the evo 8 ecu are PWM and not compatible with the DSM fans. You can hook both the AC fan and the normal fan to the AC output and both fans will turn on when cooling is required (its not a bad situation really to have both triggered from the AC output). You can use the fan tables in ecuflash to modify the behavior of the AC fan output to your liking. The only thing that is lost is individual fan control in that simple setup.

Another method is to modify the circuit so that one fan turns on to high from the AC LOW output and then both fans turn on to high from the AC HIGH output. This is easy to do with diodes and gives you that more progressive fan behavior seen from the factory.

Finally, you can modify the PWM fan tables to set 100% ground and perhaps have luck triggering the relays for the fan using the 100% ground PWM output from the normal output on the ecu. I have seen a few post where people have got this to work and in theory you can achieve factory like fan control with this. I gave it a quick try without luck, but I didn't put much of an effort into it because I don't mind having just two outputs from the ECU to control the fans (AC LOW and AC HIGH).

I have attached my ECU conversion pin out diagrams for reference, in case someone doesn't want to go to DSM talk or tuners...

onefast2gdsm

3G ecus dont have ac relay pins so thats why my fans dont work. Theyre controlled by the fan controller. I wired my fans to a switch and they work fine now.

silver2gst

Sorry. I thought the 3G ECU was identical to the EVO 8 ECU except missing the boost control output pins. My bad.