I'm fixing to get my harness in for my 05 efans, can I use my stock 99 PCM that has been sitting in my shed , and use that to retune my truck and turn the fans on? I have a custom tune in there now, but they also locked my PCM , I bought this PCM with the tune already in it from a guy on here about 5 years ago. Thanks

 

Yep. Im using my 1999 pcm to control my 2005 efans.

 

Yes it will work if you activate the fan in the tune, but if the PCM has a tuner lock some one will have to unlock it to adjust the parameters.

 

Cant you get the dealer to reflash it with an updated GM tune with the tech II?

 

Don't know anyone at a Chevy dealer. Best friends with a master tech at a ford dealer, they have "all data" , could he use that? And does my stock PCM have to be reflashed before I tune it, or would it be just best.

 

No, alldata is not going to help. It will take either a tech 2 or mdi. Problem is even then, there wasn't an operating system from 99-02 (besides the fbodies) that was equipped with efans (unless I am mistaken and I very well may be). 03 and newer pcms were drive by wire and were different than the 02 and prior.

 

I thought the drive by wire wasn't until 05 and up ?

 

Different vehicles came with different throttle bodies. My 01 came with DBW. Bit I believe it was 03 for dbw.

 

My understanding is that you can flash over a tuner locked PCM with a factory calibration. I have not done this so I am not 100%

I do know that the early 99-02 GM Truck ECU is capable of running E-fans but it has to be turned on with aftermarket software like EFI live or HP tuners.

The GM Tech 2 and the GM MDI can NOT modify calibration tables. The GM Tech 2 and GM MDI can only Transfer the calibration files and be used for diagnostic purposes. GM does not allow there techs or dealers to modify the calibrations for the engine or transmission. Probably for liability reasons and to keep down on unnecessary warranty claims. They can not even change gear ratios at the dealer. It requires approval from corporate and IF and only IF the request is approved they will modify the calibration and post it on there secure server for the Technician to download and flash into the Vehicle. GM will also update there system noting the change so should there be an issue with the gears or should the vehicle ever need to be re-flashed the correct information is available.

When it comes to accessories like fog lights, Gm offers additional calibrations for the module that will control it. The tech simply loads the proper calibration for the option he wishes to add.

Just an FYI about DBW. Although not very common, some 99-02 Trucks and SUV's were equipped with Fly by wire throttle bodies. I believe the vehicle had to be equipped with Active ride control suspension and possibly traction control.

Also GMT800 G body gas van's from 03- up still used a cable throttle body. So the Vans OS can be used in a truck if you modify the harness to match.


HTH

 

Yes a tuner locked pcm can be flashed over with gm equipment. I work at a dealer...lol. I have to do it regularly. Sure gm will give you an alternate cal for accessories, but not fans.