Dudemaaanownsanrx7

iTrader: (23)

well yesterday a couple wires somehow shorted out at the front harness near my passenger headlight. I got the wires repaired, one was a large blue wire the other a brown/white wire and the 3rd was a green/yellow wire.

Afterwards my fans wouldnt come on with the Power FC settings. They would come on immediately if i turned the A/C switch on, and ive been running them this way to keep the engine cool. The 4th relay that looks different then the other 3 i believe is the one that is controlled by the A/C switch its working fine.

I was trying to test the other relays and they appeared to be working at first, at least 2 of the 3. Then i got a little confused as to which was which and then they all seemed like they checked out, then i dont know if i did something but none of the 3 seemed like they were working correctly after that. So maybe i messed them up or something.

I'm going to try to get new relays but i need to know a couple things after i get them.

One of the relays has a Large black wire, after putting a voltmeter on it, i discovered this black wire is a ground, or is grounding out. I dont know which is the case, so i need to know is this wire supposed to be grounded or supposed to have positve voltage?

Reading the workshop manual is said to apply voltage to relay terminals C and D then check continuity between a- b. Well my black wire is on terminal D and its grounded out, so if i connect power to this wire i just get sparks. (thats how i found out it was grounded, i then did a continuity test between it and ground to verify)

I would like to test to make sure the ECU is sending the signal to turn the fans on. I will set the fans to 0 and then test whichever wire(s) i need to. On the ECU what wire(s) is this and at the relays which wire/wires is this?

Dudemaaanownsanrx7

iTrader: (23)

i think i made a mistake in my above post, i think the LArge black wire is actually terminal A, which in the FSM is not instructed to have voltage applied.. That might be where my confusion and problem (possibly created by me) lies.

Though that doesnt explain why the fans didnt come on with the ECU. unless the original wires grounding out fried one of the relays.. and then my mistakenly reading the wrong terminals fried the other ones.

I would still like to know if this large black wire relay 2 i think terminal A, if its supposed to be a ground?

Dudemaaanownsanrx7

iTrader: (23)

ok the black wire according to the wiring diagram i found does get grounded. It was also relay 3 not 2. now i just need to figure out which wires have power from the ECU.

EDIT: appears to be relay 2 and 4 Green and black wire comes from the ecu + v

EDIT/EDIT: ok i figured out all the relays and verified the ecu is sending power to G/B on relays 2/4. i am getting 5v from the Green/Black wire with fan temp set at 0. When i increase the temp i get 0 voltage just as supposed to. Now the only question i need answered at this point. Is the 5 volts normal from the ecu or is it supposed to be 12v?

Dudemaaanownsanrx7

iTrader: (23)

ok well i got the relays in, and my problem is still there. i tested the relays and they all work. i discovered my old ones were working too. all but one of them anyways.

The problem seems to be the ECU is not grounding out the GREEN/Black wires on relays 2 and 4. What could the problem be?

If i unplug the relays, the green/black wires on relays 2 and 4 will receive power from the ECU 5v's positive voltage when i set the power fc to turn the fans on at 0. if i set them to a higher temperature then what the water temp is the voltage goes to 0. I'm under the impression that it's supposed to ground out the G/B wire, so why am i seeing 5v positive?

Dudemaaanownsanrx7

iTrader: (23)

ok i tested at my ecu and found that pin 3d is not grounding out at the ECU. the ecu still displays the temperature of the water on my datalogit. DO the fans use the same sensor or is it a different one? Im trying to narrow down if its my ECU or a thermo sensor that tells the ecu when to ground out. There is also mention of the powertrain module or something what does it do in all of this?

Mahjik

iTrader: (1)

I believe without the Datalogic, the PFC just uses the same mechanism as stock to control the fans. If so, you need to check/test your Thermoswitch rather than the Thermosensor.

Dudemaaanownsanrx7

iTrader: (23)

if my thermoswitch is bad will that cause relays 2 and 4 to not work too or just relay 3?

Relay one works, and relay 3 im not concerned with at this point, but relays 2 and 4 arent being grounded out by whatever does this. I dont know if it's because they arent receiving the signal that the temp is hot enough to turn on (thermoswitch?) or if the PCME? is malfuntioning? (what is the PCME?)

Mahjik

iTrader: (1)

That should only effect relay 3 which would stop the fans from coming on at Medium or High.

PCME is just the ECU. The temperature signal should be coming from the Thermosensor. However, if you have the Fuel and Coolant thermosensor connectors backwards, that would cause you a problem as they are close enough to do that.

Have you verifed you are getting/reading 221F without the fans coming on?

Dudemaaanownsanrx7

iTrader: (23)

well i have the pfc which allows me to lower the temperature. i used to be able to just put in 0 or any number lower then the water temp and the fans would come on. Then i had some wires short out, after fixing them the fans didnt seem to come on correctly. I havent changed any of the connectors as far as the fuel and coolant. The wire that is supposed to ground out at the ecu doesnt ground out. Is this controlled inside the ECU? My pfc still displays the temperature just as it did before.

EDIT: i also have 12v positive voltage from the wire that's supposed to ground out at the ECU don't know if this is normal or not? When i ground it out the fans come on like they are supposed to.

dhays

iTrader: (1)

All that is good information.

I've seen that on my '94 touring, the fans will also come on at around 200F if I turn the parking lights on. Once the fans are running at low, turning on the parking lights does not effect fan speed. I believe that somehow the ECU kicks on relays 2 & 4 at a lower temp if the parking lights are on.

Dudemaaanownsanrx7

iTrader: (23)

i'm thinking i might just get an adjustable thermal switch and be done with it. tie it into the stock relays, the fans will stay on with the engine off until the temp reaches whatever temp

dhays

iTrader: (1)

I've wondered about that as well. I've had other cars that did that. I'm just not sure how effective keeping the fans running would be since the coolant in the radiator will cool down, but since it isn't circulating just the fans aren't going to cool the engine much with a stock hood closed. Popping the hood may help some, but if you are going to pop the hood then the fans probably wouldn't help much anyway.

I suppose that is one situation where an electric water pump would be nice. Could you have both an electric water pump as well as the fans stay on until the engine temps came down to 220? I imagine someone had done it.

Dudemaaanownsanrx7

iTrader: (23)

well i need it to come on anyways cause apparently my ecu isnt switching it on.

Im running a vented hood. I have noticed temps often increase when you first shut off the engine, prob because the water pump isnt running anymore. having the fans run afterwards would make the engine bay cooler which is better for the parts inside and the paint on the hood. also would make it nicer for working on the car after driving it. i dont really see a downside to having them run until its a little cooler, unless you have battery problems.

petros_rx7

The ecu have to ground the g/b wire when the water temp go up to 92 c or sooner if you have change it with datalogit.
Now if the relay 2+4 didnt work you have to check pfc.
Pfc have mosfet ic to control the relay and this ic is unfused so if you have short circuit in your car probably you have burn this ic.It is easy to change it but you will need new ic if I remember well is the nec upa1500b mosfet n channel array and also a good electronic engineer with good vacuum solder iron.

Dudemaaanownsanrx7

iTrader: (23)

is that one of the tiny squares soldered on the board? i don't know ANY electrical engineers. Have you changed this piece out before? I took the PFC apart and looked inside but i couldnt find anything burned out.

There is a unit that is soldered to the board in i think 5 places and is also held on to the wall of the PFC with a little nut/bolt. (it's the only one attached to the board like this) the solders looked a little weird on it. is that the mosfet ic you're refering to?

Mahjik

iTrader: (1)

You might just bug someone in the area to trade out PFC's for a test. In Texas, I'm sure there is more than one or two PFC owners who would be more than willing to help out.

Mahjik

iTrader: (1)

Yes. When the car detects extra electrical load, that lowers the threshold for the fans. I'm not sure if the PFC emulates that.

Dudemaaanownsanrx7

iTrader: (23)

i could swap my stock one too and see if it ever triggers relays 2/4, i'm pretty sure it must be the PFC though, it makes sense. and i traced it all the way back to the ecu. it's just not grounding out when it reaches the correct temperature. Nothing else was changed with the wiring, the blown fuse was replaced, so it prob just shorted out in the PFC.

Mahjik

iTrader: (1)

IMO, that's the next logical step (stock ECU or another PFC). Post back your results.

Dudemaaanownsanrx7

iTrader: (23)

i would like to test with another pfc since i would be able to switch the fans on immediately to test rather then waiting for the temp to reach 221F degrees. (105C) But no one in my area even has an rx7. closest ppl with PFC in an rx7 is like an hr and a half away or so

Dudemaaanownsanrx7

iTrader: (23)

i went to the autoparts store and picked up an electric fan thermostat, it's adjustable from 116 degrees up to like 250 or so. instead of wiring it according to the directions providing + power directly to the fans, i wired it in with my stock relays 2/4 g/b wire, and used a ground as the switched source. It also has another wire that by passes the thermostat that is normally tied into the A/C switch, but since my a/c relay works fine i'm going to put it on a switch that i can manually use if i want.

The thermostat kit was like 35 dollars.