2slo4my7

iTrader: (3)

Thanks for your help Kevin!

Are you sure the fans would turn off at 185F? I have the FC thermoswitch and the fans turn on at around 205-207F on my gauge (reading from TB line) so probably real temp of 202F but then turn off again at around 200F on my gauge or again real temp of 195F since my gauge seems to read warm by about 5F.

KevinK2

The FC thermoswitch I tested was N350-18-840, could it be different vs yours? I tested it twice, and both times with a slow cool it changed back to open as it hit 185F on the way down.

If you have the stock T-stat, full open at 203F, it could be that as the coolant cooled, the T-stat started closing. Beyond that I would have to check my spare waterpump housing to see if the bypass line is pulled from the back of the block, with more stable temps, vs where the switch is perhaps influenced by water returning from the radiator. Could take a while.

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KevinK2

Going back to your post, you ask an "either or" question, and then want a yes or no response. Mr Lee, you have a habbit of not being specific enough for me to understand what you are wanting to say.

And, you can search for a copy of the circuit diagram, Z-42, B-2, from the 1993 wiring Diagram workbook.

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2slo4my7

iTrader: (3)

Good question. I changed it a long time ago and wouldn't know the number. I don't think it's possible for me to tell when it's on the car right?

Boost Lee

iTrader: (3)

Hello again Kevin! I've come to like these evening exchanges!!!

To answer your question about the fans having 0V on their inputs... Think about it, like you said, there is a constant ground to both of the fans. If 12V was ever applied to either of the inputs, then the fans would turn on.

Your statement that there is voltage to the fans most/all the time is not supported by the wiring diagram. The whole point of relay #1, #2 and #4 is to provide 12V to the fans when an input is triggered. If the configuration you're eluding to is what you've experienced, then it suggests is that your wiring has been modified from the factory configuration.

By the way, I agree there is a permanent ground on each fan and the thermoswitch triggers the second ground via relay #3.

If your statement above that I quoted above were true, in that:
a) The fans have a permanent ground (I agree)
b) There is 12V "most/all" the time to the fans (I disagree)

Then the fans would run "most/all" the time from Key On, right? But they don't, so it appears that you are incorrect.

I just went out and performed a test to confirm what the wiring diagram suggests (0V at the fans until an input is triggered). I looked for 12V going to any of the 4 wires going to each of the fans... with the Key On, Engine Off. None of the 4 wires had voltage. I then ran the engine, and again none of the 4 wires had voltage.

This proves that the fans do not receive any voltage when there are no inputs, it also proves that the ground provided to the fans when the FC thermoswitch and subsequent relay are activated will not turn on the fans because there is no voltage going to the fans at Key On.

Now... I've read through the rest of your post and agree with somethings you said (The FC switch does indeed eliminated the low speed) but realized that you didn't even install the FC Thermo switch, which means you're commenting on this topic based on your theory of what is happening rather than commenting on your experience of what actually happens (which I feel I am doing). I think we should be comparing the same thing instead of going back and forth in a theory vs. application discussion.

Could you please test your car and then verify / reject the following (no theory, actual test):
1)In an OEM wiring configuration there isn't 12V going to the fans "most/all" the time.
2)In an OEM wiring configuration triggering the fan switch (with all other inputs turned off) does NOT turn on the fans.

If you like, we can talk on the phone and clear this up so that we can post our findings rather than the ongoing deliberation.

Boost Lee

iTrader: (3)

I apologize, I meant to ask:

With all other fan inputs turned off, do the fans turn on at lower TEMP when the FC Thermoswitch provides a ground to relay #3 at 201F instead of 226F (stock thermoswitch activation temp)?

Yeah, that was totally unclear before!
BTW the diagram you refer to is attached to the first post in this thread.

KevinK2

Nope. Yes there is 1 constant gnd to the motors, but since there are 2 gnd connections to ea motor, then I assume they are independent of each other, ie one gnd is variable, the other fixed. Same deal with the grounds. So it depends on which voltage input is used, and which gnd is used, at the motor, as to if the motor will turn on. Your statement implies the A & B terminals are joined inside the motor, same deal with C & D. I think they are all independent, or you would have 1 input and 1 gnd connection.


You are forgetting that the fans are also controlled by providing a ground to the motors, by way of relay #3 and the fan switch. The voltage to the motors may turn on at that point, by way of the ecu, or it may be there already.

The "most/all" condition may be wrong , as it was based on the ability to jump the fan-thermo-switch with my parralel switch, with the ign on, but engine not running. Voltage could be provided for that, by the FCM (fan control module). The wiring was not mod'd, I'm the 2nd owner, and the 1st owner just wanted to look good in the car ...... it was NOT mod'd.

Yea!, but they are independent grounds.

as I said above, that was wrong, and I explained why.

Great job with testing, I agree with these conclusions.

Nope. You don't undersatand the diagram fully. The ecm, with IGN on ( which I hope is what you mean by "key on" ... two clicks) is capable of providing gnds to the motor relays. Try grounding terminal B on relay #3, and turning key to ign on. Fans shoul run at med speed. Just run a few sec's. They may carry on 10 minutes at lower speed with gnd removed and IGN off, based on the FCM.

I provided the effect of the thermo-switch turning on, and then the AC on, by testing. You measured voltage at the motors, a good thing too. In the end, I will be the better at reading the circuit diagram, since my position the the fan turns on at an lower temperature will show your thread premise to be WRONG.

No need to test. #1 I have conceeded. #2 You are wrong, because you do not consider the "IGN ON" as the inputs you have spoken of. That allows the fans to come on with the switch.

Thanks, but I think we are almost done here. You are a smart guy, and once you consider the influence of the ecm being able to supply voltage to the motors (that I have verified by test results), and the related flaws in your logic, you will get it.

Did you miss this valuable input?

Did we bet on who is right here?

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KevinK2

Nope. That is from the "service highlights" summary book (which I have). What I refered to is a book, separate from the big FSM that I also have, that is the service manual for the wiring, with fold out complete wiring diagrams.

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Boost Lee

iTrader: (3)

Hey Kevin

I ran out and applied ground to connector B on on relay #3 with the Key On (2 clicks). The relay clicks happily each time I apply ground to the coil, but the fans don't turn on.

Relays #1, #2, #4 provide 12V to the fans, not ground. Only Relay #3 provides a ground to the fans. In order for the triggering of Relay #3 to turn on the fans, something else must also trigger 12V to the fans, right? (You conceded that 12V isn't always present @ the fans)

When relay #3 is triggered and the resulting ground is applied to the fans, where does the required 12V source to the fans come from? What triggers it? Please explain the path of items triggered to make that happen.

Please post the wiring diagram that supports your statement. I wonder if you and I are looking at different reference material.

Mazderati

iTrader: (3)

This is great.

KevinK2

Hey Kevin


I ran out and applied ground to connector B on on relay #3 with the Key On (2 clicks). The relay clicks happily each time I apply ground to the coil, but the fans don't turn on.

Response: When I said "gnd to connector B" , did you just pull the connector off and provide a ground to the B position? What you have to do is make jumpers for all the connections, with a Y on the B connector that you put to ground. Did you make all these jumpers? I have done the same thing for other connectors where I wanted to gnd one of the terminals.

It is obvious that you need to make the jumpers, to avoid unplugging all 4 wires in the relay.


Relays #1, #2, #4 provide 12V to the fans, not ground. Only Relay #3 provides a ground to the fans. In order for the triggering of Relay #3 to turn on the fans, something else must also trigger 12V to the fans, right? (You conceded that 12V isn't always present @ the fans)

Response: You just repeated what I said in the 1st sentence, and did not read my 2nd sentence:
"The voltage to the motors may turn on at that point, by way of the ecu, or it may be there already."

When relay #3 is triggered and the resulting ground is applied to the fans, where does the required 12V source to the fans come from? What triggers it? Please explain the path of items triggered to make that happen.

Response: For the ~4th time ... LOOK at your wiring diagram from the 93 Service Highlights, and the gnd provided by the ecm or FCM.

Please post the wiring diagram that supports your statement. I wonder if you and I are looking at different reference material. There is a ground line for the two motor relays that comes from the ECM, on the lower right corner. When grounded, the motor relays provide voltage to the motors.

Response: There is nothing of significance in my 93 Factory Wiring Diagram that is not shown in the diagram you have, and it supports my statement. It is consistent with my test with ign on, engine off, tripping the fan-switch gnd (with another parallel switch) turns on the fans.

Comment: At this point it obvious you are not experienced in this specific type of auto wiring diagram interpretation. In spite of my repeated references to the ecu and it's grounding function for the relays, you don't get it.


Most important, you ignored this comment I made:

Originally Posted by 2slo4my7
...... I have the FC thermoswitch and the fans turn on at around 205-207F on my gauge (reading from TB line) so probably real temp of 202F ......

That data completely blows away your purpose for this flawed thread, in that adding the FC switch DOES lower the temps when the fans come on.

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KevinK2

Boost Lee,

At this point the discussion has become repetitive, as it seems you do not read my responses completely as of late. You did find a couple of mistakes I made, but I corrected them and they were done with, not returning as an issue again and again. Please read thoroughly before responding.

Thanx, Kevin


BTW, rather than make the jumpers to gnd that terminal, you can do the same thing by just grounding the black "test wire pigtail" that comes from the FCM, behind the ecu on the right kick pannel on the passenger side. This is the wire I used for my extra "on demand" fan switch.

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Boost Lee

iTrader: (3)

I did not disconnect the connector from the relay, I used an alligator clip and jumped wire B to ground while still connected to the relay. I even tried grounding the pigtail near the ECU.

I've repeated myself because you've not answered my question. When the thermoswitch is triggered it provides a ground to relay #3, and your statement that the ECU then somehow provides 12V isn't proven by anything. My test last night didn't prove it. I've looked at the diagram to see if somehow the ECU is aware of the thermoswitch being triggered and there's no connection between the thermoswitch and the ECU. So how is it possible for the ECU to trigger relay #2 and #4 when the thermoswitch is triggered when the ECU is not aware of the thermoswitch?

I've asked a few times for you to post the reference material you're using so I can see the documentation you get your perspective from, but instead you've asked me to perform tests which I've done, and both had results that were contrary to your statements. You conceded on the first, and I'm waiting on the second.

All I'm asking from you is the documentation you're using to make the statement that the thermoswitch magically alerts the ECU to provide 12V to the fans (via relay or whatever). I just don't see it.

I'm perfectly able to read a wiring diagram, I just can't infer something that hasn't been shown. We've gone at this for a few days without throwing insults at each others ability or logic. We're both ready to end this, but let's try and keep the civility going!

BTW I'm using a 94 diagram for my 94 car not a 93.


2slo4my7 isn't using a stock ECU, he's using a Petit ECU unit. Because of this, I can't assume the same situation applies to him, so I won't include his response.

Let's finish this off and prove that people coming from two different perspectives can actually arrive at the truth on the Internet.

BTW as a result of yesterdays test, I made a modifcation to my car. On the connector that goes to the fan control module, I connected the wire from the thermoswitch to the wire that provides ground for relay #2 and #4 using a jumper. This now allows the thermoswitch to provide ground to relay #2, #3, #4 at the same time. My fans now come on @medium speed when the thermoswitch is triggered. I left that connector disconnected from the fan control unit for now.

Boost Lee

iTrader: (3)

It appears I'm not the only one who realized this!

https://www.rx7club.com/3rd-generati...g-fans-462760/

KevinK2

Ok, I see the source of the repitition. Including the 2 trigger link, there are 3 different wiring diagrams from the Factory wiring manual in play now:

1) Yours on page 1, post 1
2) The one on Two Trigger Fans
3) My 93 diagram, which is the same as the section F of the 93 "highlights" diagram on post#5

I'm sorry I said you could not read the diagram correctly, we were NOT looking at the same one.

If you look at post 5, that is what I was refering too in this thread. That includes the fan control recall, that includes the FCModule shown on the right. This should make more sense to you, as there is a gnd wire going to the ecm.

About the Pettit ecu, I have a similar one from the expired "XS Engineering" (not installed now). They install a motherboard that will except the plugin boards with different boost, timing, and fuel maps. That's it. There is no change in how the fans work. It was provided by Techtom, who made the parts an about 4 different "daughter" board chips, based on what other mods were done to the engine, intake, and exhaust.

And perhaps that explains most of our differences. But we have a 94 where the fans turn on at 203 with the FC switch (with chipped board), and my 93 where I can simulate the switch closing at cold conditions.

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Mps_hell

Some people on here are very fast to repeat what someone else told them with out trying to find out for them self what their own car is doing. I have two daviescraig Thermatic Switch (Part No: 0400). It is a work in progress for me however you seem to be on the same path I was on till I got the ***** and cut the lot out.

I can however tell you that despite what people on here like to tell you it is possible to get way more cooling out of the stock rad set up on these cars with a 75C thermostat and better relays ( at one point I couldn't get my car over 80c in town stop and go traffic driving like a ****)

Your getting closer to solving the cooling issues. I can feel the dark side within you


you will also find that the stock wiring..... like the rest of the car wiring is a pos and gets hot when running speed 2 and even hotter on speed 3

KevinK2

One thing that derailed our communication was that the diagram in post 5 was just like mine, and not like your diagram in post 1. I did not hear anything about them being different, so I thought you were using that diagram, like mine. Glad you got your model to work like at least 2 other cars.

Do you think that it was possible your fans would come on early with the FC switch, based on the 150 sec delay when tested indirectly? You heard a click ... could have been a timer.


Recall Test Proceedure:

In my notes, I copied a test proceedure from the recall #60504 TSB for checking out the FCM. The first part says to gnd the test wire (parallel with switch) and fan comes on 150 sec AFTER you turn ign on.

It also notes that before Apr 1 93, P0210660, fan operates with no delay

And after that date, P0210661, fan comes on 100-150 sec after key on.

I assume this is for the test proceedure only.

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Boost Lee

iTrader: (3)

I can't allow chipped ECU's to be part of this example. There's no way to be 100% certain that fan switching hasn't been altered in them. I totally hear what you're saying about only remapping fuel and timing, but without documentation we can't be certain. I'm trying to remain specific to stock ECU and stock harnessed vehicles.

OK Onward!!!!

I think I get your perspective now that I've looked at that diagram. You're saying that the thermoswitch state is sent to the FCM which is also connected to the ECU and then the ECU or FCM then provide the ground to activate relay #2 and #4?

Ok. The thermoswitch is connected to FCM pin C. The FCM pin E is connected to ECU pin 3D. But it's marked as an output by the service manual (documentation attached). To me this means the ECU doesn't read signal from this wire and there is no logic performed by the ECU based on the state of signal on 3D. So I concluding the thermoswitch wouldn't have any impact on the ECU. The diagram in post #5 doesn't show another thermoswitch connection to the ECU, even proxied by another device. Do you agree?

This leaves the FCM as the only item that can trigger the fans. In order for the FCM to switch relay #2 and #4, it would need to internally connect pin E to ground. But wait...last night I had to make a jumper that did EXACTLY that. (I referred to it in post #38. So I think here are the options:

1) I have a bad FCM, which blows my entire thesis out of the water and I owe you a set of FD spark plugs (that was the bet I made in my head)

2) The cars you've been playing with have a minor modification from stock and you owe me a Ferrari 458 (that was the other half of the bet I made in my head)

Does what I've whittled it down to sound reasonable? (With the exception of the 458... a Tesla will do)


I don't know the normal behavior of the FCM and there's no reference that I've found. SO... how do we test it?

Boost Lee

iTrader: (3)

I didn't know there was a timer. I gotta test the timer!!!!!

Boost Lee

iTrader: (3)

Ok... So I applied the ground and then did the Key On... no Fans.

However, just days ago my car did keep the fans going for about 10 minutes after i shut it off warm, suggesting that the FCM was functioning then. I suppose I'll need to find another one to test with, huh?

adam c

iTrader: (2)

This is correct. I had (still have it in my garage) an M2 stage 3 ecu. I went to Mostly Mazda (M2) in July of 2003. A fat guy in a PT cruiser showed up, and took my stock ecu. He soldered in a board with new timing, boost and fuel maps. That's it!! No cooling mods were made. It was in my car for many years after that.

I installed an FC thermoswitch in July of 2007. It worked for me, like it has for so many others. I cant comment on why it works, I just know it does.

Boost Lee

iTrader: (3)

Where do I find a 75C thermostat? Having one of those will allow me to run a different thermoswitch that won't conflict so heavily with the stock thermostat opening temperature. I can have the fans come on at 195-200 and shut off at 180.

KevinK2

Did you wait 150 secs with key on back then?

The timer is in the FCM. It will run at med speed until temp is below 221 (FD switch) then it finishes at low speed.

Mps_hell

Billion - Performance Thermostats - Nengun Performance

Mine was in the car when i came from japan. I am using an 82c one ATM but like i said I am still working on it

KevinK2

A vote for the FCM

When I used the FD for some DD duties, I was glad I had the "fan mod" switch that allowed me to park the car in some open lot in the sun on a hot summer day. I used the left position oem console switch to gnd the FCM test wire. Turn switch on (closed) ~2 minutes before arrival, and then turn it off, when parked and fan would run on at mid speed for near 10 minutes, switching to low speed, then turned off. You could feel the hot air exiting from under the car. Also handy when cooling down in the pits after a 20 minute track session with lots of WOT running.

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