Another Cooling Fan Activation Issue!
 

I recently installed the Mishimoto radiator along with 2 12" ebay slim fans. I also did the upgrade to HiRes 10g firmware and code. The car runs fine but now I have an issue with the main cooling fan not turning on. I have read
this post
https://www.miataturbo.net/forum/sho...ooling+fanpost
and have tried all the steps. I still can't get the fan to come on. When I did the radiator install I did notice that I blew the fan fuse so I replaced it but still did not the get the fan to come on so I tested the sensor and the fan relay. Just to be sure I replaced the realy with a new one, yet no fan still. A few days back I checked all the wiring and made sure nothing was crimped and checked the fuse and realy again. For a moment the fan all the sudden came on. Then the next day it stopped working again. I reflashed the firmware today and also ran it through Easy therm. Can someone help with this?

did you remove the plug from the clt temp sender on the t-stat housing? or did it get damaged?

I'm not very familiar with the 1.6's but I know that sensor/thermoswitch activates the fans directly in factory form. Does it also do that with the MSPNP? Does the MSPNP use that sensor for CLT or is there also a sensor at the back of the head like the 1.8? What coolant temps are you seeing in Megatune?

There is a temp sensor that I believe controls the fan that is in front of the motor. I did check it for resistance with an ohm meter and it looked ok. I am not sure if there is one on the back too like the 1.8. Since the bigger radiator the temps seem to hold normal and megatune does show it reading up to 215 degree by default but not above it. I can see it as it warms up and shows the temps and hold at about the right temperature, but when it gets hoter the fan won't turn on. It seems like the sensor is working as it should.

make sure the contacts are good on that connector for the thermoswitch. make sure the wire is intact and didn't get damaged when swapping the rad.

Wait, did these ebay fans ever work? What happens when you jump the fan in the diagnostic box?

The contacts are clean and the thermoswitch is intact. The fans do work and did turn on after the radiator install. I am not sure what you mean by the jump test, but I did remove the fan relay and did a jump test there and the fan does come on.

Easytherm, what values did you use for the CLT?

Do the thermfactor.inc file in the source and mtcfg folders match?

I used the standard rx7 settings which are
2490 bias
-20 16200
20 2450
80 320
I did not change the intake Air temp values and left what was there:

20 41500
50 11850
85 3500
code version to custom.

I am not sure which files need to match. Can you tell me which paths im supposed to look in to see if the thermfactor.inc file in the source and mtcfg folders match?

C:\Program Files\MegaSquirt\2 DD with HiRes PNP 10g\src\thermfactor.inc
C:\Program Files\MegaSquirt\2 DD with HiRes PNP 10g\mtCfg\thermfactor.inc

the inc file in the src folder gets burned to the megasquirt so it can translate the readings from the sensor into temperature values.

the inc file in the mtcfg file tells the Megatune program how to translate readings it receives from the MS into temperature values.

If those files don't match the temp you see in MT won't be the temp your MS is seeing. So it's possible that the temp is actually 200 but MT shows it as 215 due to incorrect inc files. First verify those files are the same. You should copied the inc files Easytherm created to both those directories. Next I would verify the coolant temp with a thermometer in the radiator.

"2 DD with HiRes PNP 10g" is what my car folder is called.

ok the three .inc files that Easy therm created did not match the ones that were in the src folder. I just copied the new ones over to the src folder. Do I need to burn my map to MS again after this? I don't have a thermometer at the moment I can try that tomorrrow after work.

DIY has some funky inc files which have extra columns over what easytherm creates. i don't know why. You should have also copied the newly created inc files to your mtcfg folder in your working directory.

If you indeed burned HiRes to your MS you must have then burned your current msq to it or not only wouldn't the car run, but you would fry your ignitor. So did you burn the new firmware to your MS?

I did burn firmware to ms and did burn the msq the car did run fine. When you say to copy them to the working directory too do you mean this path?
C:\Program Files\MegaSquirt\MegaTune2.25\carMtCfg
or
C:\Program Files\MegaSquirt\MegaTune2.25\mtCfg
both of these folders have a different version than the easytherm version.

i meant the paths i listed above. since i have more than one car and i setup/tune a lot of my friend's squirted miatas i use the mtcfg folder i listed. Since each of the cars can be different setups standalone vs parallel on different year cars they require their own inc files

I did match the files in both folders you listed above.

PS- I'd like to express my sincere and humble gratitude to our most excellent moderatorial staff for moving this thread to the correct forum, a task which exceeded the abilities of my own enfeebled mind. :D

Lets just make sure we're all on the same page here.

From '90-'93, fan operation was controlled by a simple on/off thermoswitch on the top of the thermostat housing. If you remove the connector from this switch and ground it out, the fan should turn on, a test which will validate the majority of the fan circuit. This circuit does not involve the ECU. The thermoswitch simply completes the path to ground for the Cooling Fan Relay.

The ECU can also control the Cooling Fan Relay by providing a closure to ground on 1R. This was originally a sense line to tell the ECU that the fan was on, but like so many things, it can work both ways. Providing a closure to ground on this line will also enable the primary fan.

I actually did try that and I don't think the fan came on from what I remember.

Then there's something amiss in the circuit somewhere. check your fuse again.

Just to be sure, I just tried grounding the sensor again and the fan does not come on. The realy and fuse are new. I just don't get it.

So much blathering misinformation...

If grounding out the lead going to the thermoswitch on the thermostat housing didn't activate the fan, then at least you've got a relatively well defined area to troubleshoot. Here's the schematic for the whole fan control system:

http://img29.picoodle.com/data/img29...nm_e2c17fa.gif


Pretty simple, eh? Power comes in from the Main Relay (which we know is fine) to supply the coil of he fan relay, then that goes to ground through the thermoswitch. You could measure for the presence of +12 on the B/G wire, just to verify that the coil is ok.

When the relay closes, power comes in from the Cooling Fan fuse, through the relay, and through the fan to ground. With the fan disconnected, you should get +12 on the Y wire when you short the B/G wire to ground.

So you've really only got a couple of places to check. Shouldn't take long.

Ok now I'm getting pist. I went out today after work and started to check everything again to trying to follow the things Joe listed. I first started with the theroswitch again and had the same results and got no fan to turn on. Then I checked the fuse box to make sure the fuse is ok. Then pulled the fan relay and when I was putting it back in the damn fan came on since the car was still warm and I had just reflashed the ECU. Then fan came on for a few seconds then off again. I wigeled the relay a few times and then the fan came on again. This time it stayed on. I drove the car around just to make sure its working. Came back home parked the car and let it idle untill it got hot again but the fan is not coming on again. I was going to unbold the fuse box and see if the wiring under it is ok and nothing is loose but it started to rain so I will have to try another day. Can't figure out what the issue is.

Actually, it sounds to me like you're zeroing in on the problem quite nicely- touching and moving the relay causes it to come on when all other conditions for operation are met. Thus, either the relay, or the receptacles that it plugs into, are bad.