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HELP NEEDED: Stock fan control w/ LT-9c

Old 05-11-16, 05:13 PM
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HELP NEEDED: Stock fan control w/ LT-9c

Hey guys,

I currently have Flex-A-Lite fans in stock shrouds in a SMIC setup. The previous owner used these because his ECU at the time could not control the temperature the fans would turn on at, and so this system was used with a separate control module to control fan operation by a thermoswitch which routes to the fins in the radiator.

I bought a set of stock fans, with shrouds and want to use that with the Microtech so I can go back to a more factory setup. These fans simply don't cool enough while the A/C is on. With A/C running the temperatures slowly rise for some reason.

Please help me to understand how I need to wire the stock fans/relay etc, with the Microtech LT-9c. I can pretty easily do the physical side of things as far as installing the new fan set, but the wiring is scary.

Any help would be appreciated.

Thank you!

Nick
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Old 05-15-16, 10:02 AM
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See the schematic here:

How To Properly Install An Electric Fan

Instead of connecting pin 86 of the relay to the thermostat, connect it to the LT9c aux output.
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Old 05-15-16, 11:47 PM
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Originally Posted by Aaron Cake View Post
See the schematic here:

How To Properly Install An Electric Fan

Instead of connecting pin 86 of the relay to the thermostat, connect it to the LT9c aux output.
Thank you Aaron! Because I'm running two fans, would I need to use two relays? I thought I read that somewhere...?

I will be getting my serial -> USB adapter soon so I can control functions in the computer. I will also try my hand at tuning the car too, but that's for another thread.

Thanks for your help!

Nick
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Old 05-20-16, 08:00 PM
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fans are usually high watt items.. if you have 30amp relay, you need separate relay for each fan. if you got 80amp relay, you can run both together off one relay and fuse. the capacity will be written on the relay itself if you look. you can make an argument one should run separate circuit for each fan just in case one fails, but you can revisit that once you have everything else squared away.
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Old 05-28-16, 02:40 PM
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HELP NEEDED: Stock fan control w/ LT-9c

If your fan isn't triggering you could be on the wrong output , I had mine on output one which is used for rpm only and once i changef it to two it fixed the problem and works perfectly
Attached Thumbnails HELP NEEDED: Stock fan control w/ LT-9c-received_10154136367039463.jpeg  

Last edited by wthdidusay82; 05-28-16 at 02:44 PM.
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Old 05-29-16, 12:30 AM
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Thank you to everyone who's posted trying to assist!

One of my flex a lite fans was shorting out so it kept blowing the fuse to the control box, which prevented both from working. I've disconnected the shorted fan as a temporary fix. I am currently running one fan which actually isn't that bad. Certainly isn't a permanent solution though.

I need to get a serial to USB adapter but don't want to drop $100 on the Microtech version. That's all that's preventing me from getting this done!

Anyone have suggestions for a suitable replacement that won't cost so much?

Thanks!

Nick
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Old 05-31-16, 09:10 AM
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You have to use their adapter you have no choice , you won't be able to communicate between your standalone and laptop without. Micro tech did it this to make more money forcing your hand. The only other option is a handset.
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Old 05-31-16, 09:11 AM
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Only way to do it cheaper is to replicate their dongle yourself , if you're a tech savy.
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Old 05-31-16, 09:26 PM
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Originally Posted by wthdidusay82 View Post
Only way to do it cheaper is to replicate their dongle yourself , if you're a tech savy.
Hmm. Yeah I read of some guys having luck with another "generic" adapter and some not. My IT guy at work says that any one should work as there is no special functions for a serial adapter. All it does is assign COM ports he said...

We will see. I'll experiment with a Best Buy one.

Thanks!

Nick
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Old 06-02-16, 04:49 PM
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They do something to make it so it won't work...they probably change the wires around inside the adapter...I can tell you for a fact it won't work without one...at least it's not suppose to
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Old 06-04-16, 10:04 AM
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There are two adapters at play here.

The first is a USB to serial adapter. Most of these are generic based around a Prolific or FTDI chipset. In general I have had more success connecting to ECUs with adapters based on the Prolific chipset. However I recommend that if there is an option, don't use a USB adapter at all. If your laptop has a PCMCIC, PC-Card or ExpressCard slot, use that instead. Purchase a high quality serial adapter with a real UART.

For example:
https://www.startech.com/Cards-Adapt...6950~EC1S232U2

These cards work much better than USB adapters as they offer a real UART to the computer, not software emulation. ECUs are just a small bit of all the stuff I use a serial port to connect to on a regular basis and the ExpressCard/CardBus/PCMCIA adapters have a 100% success rate, while USB adapters can be spotty.

Now with Microtech, there is a 2nd adapter for whatever unknown ridiculous reason they dreamed up (my guess is that the communications protocol is so based around the hand controller that they couldn't write effective software easily without the adapter translating...plus they can charge $100 for it...I have sniffed their protocol years ago in order to make some Microtech map saving software and it truly is awful) you need an adapter between your serial port to connect to the Microtech. It's not just a gender changer, there is a microcontroller inside running doing data translation. It also contains memory ("MEMCALS") to save up to 4 maps (yay).

Ya know, I try to just take a Microtech for what it is, a reliable basic ECU, and not harp too much on how it is so convoluted and behind the times it's a wonder they are in business. But writing everything above just drills again into my head how backwards the Microtech system is.

Take a read of this and give it a try:

https://www.rx7club.com/microtech-11...-7mpg-1099752/

Then you'll wonder why Microtech is even an option.

Yes, I have a LT8s in my car, for 10 years. Does it work? Sure. Is it going to be replaced with an MS3-Pro as soon as I'm done my current Cosmo project? Yep.
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Old 12-09-16, 04:30 PM
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Hey guys, I'm reviving this thread because I've actually broken down and bought not one, but TWO Microtech adapters!! Why would anyone buy two you ask? Well, a member here sold me once that was the older 9 pin to serial type and my Startech.com adapter wouldn't interface. So, to not hold up my projects, I bought a brand new 9 pin to USB from O&J Performance in Orlando.

Now, I will be installing those fans here soon. I am wondering if I can use the factory relay system and retain the three speed fan operation, or with the Microtech am I restricted to just full speed all the time?

Thanks guys!

Nick
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Old 12-11-16, 10:30 AM
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OK, so after doing some reading I have a much better understanding of the fan system. I want to see if I get this...

OK, so basically I CAN use the factory relay system with the multiple speeds or "step" system. I simply need to wire the Aux on the Microtech and set the temperature to my desired setting. In doing so, the factory system should work as normal wherein the thermoswitch, input temperature from the Microtech and the A/C on, all act as triggers in the system from low, medium, to high speeds.

Am I correct?

If so, I will look to implement the FC thermoswitch in the setup where the following logic will play out:

- Thermoswitch triggers LOW fan speed at 206 F

- Microtech set to trigger MEDIUM fan speed at 215 F

Now, at this point the waters get a little muddy for me. I'd like to have the means to set a third trigger other than the A/C to get the fans cooking at anything above 220 F. Here's why...

Presently, when I run the A/C in my car the temperatures rise slow and steady unless on the highway. If I'm not maintaining at least 50-60 MPH the temps rise. So, to turn the A/C on to trigger the HIGH speed is counter-intuitive to me.

In saying that, I know I have some kind of problem with my system.

Any help here here would be appreciated. Thanks guys!

Nick
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Old 12-11-16, 10:31 AM
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I'm not sure why you would need 2 Microtech adapters. All that is required is a 9 pin serial port (preferably real UART like PCMCIA) and a single Microtech adapter. It has nothing to do with the number of pins. Serial ports are commonly 9 pin or 25 pin. 25 pin is obsolete, virtually nothing outside of printers or specialized equipment uses it. All serial adapters that I have seen for laptops provide DB9 connections unless they are custom for a specific purpose.

The Microtech LT9 provides only one fan output. Which limits you to a single on/off. But according to the Microtech website they do have 3 outputs. Assuming you can configure those in software to switch based on temperature, you could use them to control multi speed fans. Honestly not having an LT9c I can only guess because the manual hasn't been updated for them. Often Microtech "aux outputs" are pre-configured at the factory for a specific purpose, leaving them not usable to the customer.
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Old 12-11-16, 12:54 PM
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Originally Posted by Aaron Cake View Post
I'm not sure why you would need 2 Microtech adapters. All that is required is a 9 pin serial port (preferably real UART like PCMCIA) and a single Microtech adapter. It has nothing to do with the number of pins. Serial ports are commonly 9 pin or 25 pin. 25 pin is obsolete, virtually nothing outside of printers or specialized equipment uses it. All serial adapters that I have seen for laptops provide DB9 connections unless they are custom for a specific purpose.

The Microtech LT9 provides only one fan output. Which limits you to a single on/off. But according to the Microtech website they do have 3 outputs. Assuming you can configure those in software to switch based on temperature, you could use them to control multi speed fans. Honestly not having an LT9c I can only guess because the manual hasn't been updated for them. Often Microtech "aux outputs" are pre-configured at the factory for a specific purpose, leaving them not usable to the customer.
Thanks for replying Aaron.

The reason I got the second adapter is because I don't have a serial port on my laptop, so I had to go from the Microtech adapter to USB and it wasn't working. I've got the USB adapter from Microtech now though so it's all good.

So, plenty of people on these boards have referenced using the PFC and Datalogit to adjust one of the "steps" in the muli-speed stock setup. Are they only able to retain the stock multi speed fan function because the PFC has more aux outputs?

It seemed to me based on what I read that the factory system really only needs a signal from the thermoswitch and the ECU to step up the speeds of the fans?

Thanks for the help and clarification. Please let me know if I have it wrong here.

Nick
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Old 12-13-16, 05:27 PM
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Bueler?
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Old 12-21-16, 06:23 AM
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Old 12-21-16, 02:42 PM
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If anyone's out there...I have decided to give it a go with my stock relays. I am not sure which wire to splice into on the factory harness. Any insight on this?

White/Red wire (aux output) to ...??

Thanks!

Nick
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Old 12-25-16, 10:32 AM
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I don't have a wiring diagram for the FD but in most cases, it is as simple as switching one relay for low speed, one relay for high speed.

There's probably a link in the FD forum for the FSM which contains the diagrams.

If you have the extra AUX outputs on the Microtech, you would just set one output connected to the low speed relay to activate at a low temperature, and the other output at a high temperature.

One side of the relay coil goes to switched 12V, the other side connects to the Microtech output.
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Old 12-25-16, 12:49 PM
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Aaron, thanks for your response.

I ended up consulting with Jesus at Kilo Racing and he gave me his workaround:

Basically, all you have to do is set the AuxFan to On with whatever temperature you want, I chose 99* C. From there, splice into the green/black wire on the harness that comes out of the Electronic Load Unit, which is located in the same passenger kick panel area, tucked up under the dash. For '94+ this is a different color wire! Consult the service manual if it's a 94+ car.

What you're doing is locating the negative trigger from the EL unit, to the fan relays. The Microtech will provide the negative trigger at the specific temperature and presto! Your fans will turn on at the specific temperature.

The only downside is it appears I only have LOW and MEDIUM speed available. If I'm not using AC, the fans will only come on LOW, once the coolant temperature reaches 99* C. At that point, if I want to increase yo MEDIUM, I would have to turn on the AC.

Based on my testing I think it's sufficient, but if you had a FMIC, it probably wouldn't be good enough.

So, if I remember correctly from DaleClark's thread, relay 2 & 4 must be activated to get HIGH speed. So, I will be looking into the other Aux outputs and see if maybe I can send a second negative trigger signal at a particular temperature.

If I can figure this out, I'll report back. If anyone has any ideas on this, I'd really appreciate it. I'm basically looking for one more trigger, because with the Microtech, I don't believe the thermoswitch is factoring in...?

Nick
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Old 05-26-18, 02:04 AM
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Used a friend's computer and it worked fine. I think it is my particular install of XP that is the problem.
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