I built a bench yesterday that will allow me to flash GM PCM's out of the vehicle. I have HP Tuners but sometimes find that with the 2004, 2005, and 2006 GMC's and some Silverados that they CANNOT be flashed in the vehicle. You will continuously get "time out" errors. Yes, some, or most, of these vehicles have after market stereos installed. I've previously tried removing the fuse for the radio, and other work-arounds but with limited success. Now I have a bench that I can plug them into and flash them outside the vehicle without issue. The other times I can use this is when someone needs VATS deleted, BRAF, and VE changes to get a project vehicle up and running without having to have the car towed to my shop-such as after a cam swap and before they can drive it to me. Then later, once the vehicle is driveable they can bring it in for final tuning of the combination.

My question is this.. I've built my bench to have a continuous power source while the PCM is connected, and also a switched 12V source as well. I suspect that after burning a tune, and then turning the key off (in my case flipping a toggle switch), that the PCM should be left with continuous power on for a period to let the PCM finalize the RAM/burning process. How long should I leave the PCM connected to the bench with 12V current after burning a tune? I've been doing 5 minutes at this point just to be safe, but would not mind leaving it longer if necessary. As with anything that involves HP Tuners, I'd like to know the "gotchas!" up front, as opposed to after-the-fact which typically is the HPT way... You know you have not used HPT enough unless you have bricked multiple PCM's... Trying to avoid that process going forward if at all possible.

 

On the 04-06's you have to pull 6 fuses and you can flash them no problem in the truck. On a bench harness it is important to have the 12v batt and IGN hooked up correctly. After I flash on the bench I leave the 12v batt powered up 15-20 seconds after turning off the IGN. Have flashed thousands of ecms on the bench with no issues.

 

mini, thanks for the reply. If you know, off the top of your head, which are the 6 fuses that can be removed that would allow flashing in the vehicle? I'm sure there are many people that would like to know-myself included.

 

tbc
batt
tbc
ign1
radio
info

 

PCM Hammer and LS Droid recommend keeping the "keep alive" power on for 15-20 seconds after a write is complete and this has worked well for me.

Rick

 

mini-thanks for that information! I'm going to print it out, and then promptly lose it (as I do with anything of value that I desperately need to have!).

B52-thanks for that. I'm already leaving it on for at least 5 minutes.

 

Is it possible to flash without removing those fuses...???

I'm pretty new to this, but I've flashed my 2006 GMC 2500HD a couple times and it seemed to "take".

(But it was pretty simple stuff...speed limit change, stuff like that.)

 

Yes I only pull those when one wont flash. Have had to pull those fuses on less than 10 trucks total in 20 years,

 

I've had TWO trucks in the past that I could not flash, and then I just had a 2005 GMC in last week that I could not flash in vehicle. So 3 vehicles total in about 5 years of tuning.

 

I have found it depends on what radio harness they used (if it has after market radio) or if it has remote start or alarm connected to it. I have a 06 with the high dollar harness that I have to pull fuses everytime and I have a 04 with the cheap harness and never have to pull any fuses.

 

I am trying to put a tune on a 2004 Silverado and cannot get past saving the stock file it starts the process but loses communication. I have been trying to pull fuses but having no luck, I am going to try the fuses minytrker mentioned but I have several tbc fuses, one under the hood and 4 in the inside fuse panel by the driver's door could you help clarify which of those fuses needs pulled, thanks