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MS3x lost fan control

Old 05-08-2019, 09:20 AM
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Join Date: Oct 2017
Location: Lafayette Indiana
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Default MS3x lost fan control

Hi everybody,

I'm putting this one out to the hive mind to help me trouble shoot this issue. My MS3x lost control of my fan. I found out when I came back from driving and let it idle in the garage for like 5 minutes. Fans just decided not to come on. The fans have come on in the past before so i know the ecu has had control of it. I am currently using a single Volvo fan wired up to the stock driver side power source in a 97 miata. No AC fan hooked up atm. I'll include my MSQ just in case too.

Let me go through what I have done so far:
1)Checked the fuse
2)Checked the relay off the car with a 12v source (I could hear the coil clicking on and off)
3)Jumped GND to TFA and the fan came on (so the relay, fuse, wiring, and fan motor are all good i think, but what do i know)
4) Checked coolant level ( its full)
5)Checked tunerstudio to make sure the ECU was getting a temp input. It was it rose steadily up to 210 no big jumps.
6)Tried lowing the temp at which the fans come on. I put it to 160 but still no luck.

I've been poking around the forum for the last day and I found a post by Aidandj and in his case it was an injector driver in the ECU died. I have yet to open up my board nor do I know what to look for when diagnosing a dead driver (besides the normal stuff like heartbeat ect), but mine is a prebuilt from diyautotune, and later in the thread its mentioned that the drivers going bad is pretty rare. Any ideas on what could be happening? I'm at work atm but after I get off I'll probably try using a different trigger to see if that does anything and probably bust out the multi meter and check for continuity between the ecu and the engine bay.

If there is any other info that might help trouble shoot the issue let me know. Thanks for the brain power.
Attached Files
File Type: msq
2019-05-08_08.33.51.msq (286.8 KB, 4 views)
Nihilist is offline  
Old 05-08-2019, 10:23 AM
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Location: Belgium
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With ignition on, ground the black/green wire in position 1A. If the fan turns on, the entire wiring system in the car is working properly.
Now you know the problem lies with the Megasquirt. Set the Megasquirt in test mode and activate the fan manually.
If it doesn't turn on, chances are indeed that the injector driver is defective - or a wire came loose.
You appear to have set the fan on injector I but you also have a programmable output on injector G. You need to know which one you're using.
If an injector driver is defective, you rewire the fan to another spare injector output.
WestfieldMX5 is offline  
Old 05-08-2019, 07:57 PM
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Join Date: Oct 2017
Location: Lafayette Indiana
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Westfield thanks a whole bunch just jumped ING G to ground and the fan came on. So its the Megasquirt for sure. I'll switch this over to where the AC fan should go (INJ F) and change that around in the software. Should get me through my upcoming road trip and till I can get a new driver to solder onto the board. Thanks again.

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