LT1 PCM fan control

[wheelman]

I've wired my Taurus fan to be controlled by the LT1 PCM using 3 relays so that the low and high speed circuits will not be energized at the same time. I've had this working for months but every time I started the car after 30 seconds or so the fan would come on at low speed then switch to high speed and run continuously. No matter what I set the temp thresholds at I would see this behavior and it has really been bugging me. When I used a scanner on the PCM I always had 1 diagnostic trouble code (DTC), #11, bad SES light, showing caused by the missing SES light (I hadn't wired it up yet).

Come to find out if the PCM is setting any DTCs it will turn both fans on and leave them on. With the help of several members here and on other boards I was able to determine this was the problem and eliminate it.

 

Thanks guys and I hope this helps others avoid this problem.

 

Wheelman

[Bartman]

Thanks for posting this info wheelman. I think I've gotten to the point where I really need to be able to view and edit my PCM. I tested the outputs for my fan and I couldn't get either one to energize (after I got the water temperature high), and from the FSM it looks like by default they energize at temperatures that are too high for my tastes.

 

So which software package would be best for me with my 94 LT1 and what else would I need (connector, etc)? I think I have an old laptop that would probably do the trick.

[wheelman]

Bart,

I got a cable from AKM Electronics and use TunerCat to edit the PCM and TTS DataMaster for logging. DataMaster is very comprehensive but takes a little getting used to, TunerCat is very straight forward but there are so many tables that can be tuned in an LT1 it can be overwhelming. Tim probably already took care of most things you'll want to change so download the PCM first then start slow making small changes.

 

Do you have an ALDL connector? I have one from the donor car but hooked up a DB9 connector instead and have a short harness with another DB9 and ALDL for use with regular scanners. I did this because I bought an unassembled cable to save some money. Looking back I should have gotten a cable with the ALDL connector so I could use it with my other cars. Oh well I can always get one of those later and build another small harness.

 

I believe I have the fan set up to turn on slow at 97C and high at 101C. Once I install my 160 degree thermostat I'll set them at 87C and 96C respectively. Then I'm going to start playing with the timing and fuel maps to get rid of my rich condition.

 

Here are the links:

AKM Electroincs http://www.akmcables.com/

TunerCat http://www.tunercat.com

TTS DataMaster http://www.ttspowersystems.com/DM_Software.htm

 

Wheelman

[jbc3]

I agree that TTS Datamaster is a great data logger. I also have Diacom Plus, which actually isn't bad either. I can clear codes with Diacom, but it doesn't have the graphing features of Datamaster. You can read the Diacom files in Datamaster though.

Datamaster uses the same cable as Tunercat and LT1-edit. The Diacom cable is different. I have an open version of LT1-edit (not VIN locked).

 

Jody

[wheelman]

jcb3,

Have you used both LT1-Edit and TunerCat?

Which do you prefer?

I have TunerCat and find the number of tables you can edit to be a little overwhelming, does LT1-Edit hide some of this from you?

 

I haven't used DataMaster a lot, does it have the ability to clear codes? I was using FreeScan to do that but found it annoying because it's a resource hog and the computer becomes sluggish when logging is turned on.

 

Wheelman

[jbc3]

I have only looked over someone's shoulder using Tunercat, so I am not familiar with it at all. I am very familiar with LT1-edit and find it very easy to use. LT1-edit has alot of options and can be overwhelming also, but you can select what area you want to view/change and that is the only thing you see. There is a compare feature where you can see the difference between files and you can copy from the comparison file if you want. It has 3D graphics also. Neither program has an instruction manual that will step you through tuning a car. You need to know what you are doing and the affect of your changes, or you could have a mess. There are a ton of sources on tuning, including the LT1-edit mailing list http://www.lt1edit.com/mailman/listinfo/lt1edit and web pages like http://para.noid.org/~lj/ .

Tunercat is not vin locked, LT1-edit is. No big deal if you are only doing one vehicle. It is like $50 to add another vin to your program. There is a little program that will convert LT1-edit files to BIN (Tunercat format) and back, so you can read any file with either program.

 

You can run the '96 and '97 F-body OBDII cars with a '94 - '95 OBDI PCM if you like. You just have to change the knock sensor to the OBDI version. It will then ignore the rear O2's. The benefit to this is you can purchase the (much less expensive) OBDI version of LT1-edit to program your car. I ran an OBDI computer in my '96 Camaro for years. There are benefits to running the OBDII computer if you are running the 4L60E auto trans however.

 

As far as Datamaster, the program can be downloaded free and has like 20 free recording sessions. If you don't have it, download it and look at. It has a ton of great options to aid you in evaluating your engine's performance. It also views the DOS based Diacom files in the graphical environment. It is just a record/view program and can not clear codes.

Diacom records the same parameters, but is limited in the ways you can view the information. It will allow you to clear codes if your PCM is OBDI. Diacom will work for some of the later model OBDII cars, but you have to lie to it in set-up, giving it an OBDI VIN. It will not clear OBDII codes.

I also have Freescan and find it a pain to use.

 

Jody