question about changing OS

[Oso]

l have a 2000 5.3 with stage 2 cam cold air and electric fans. i used lsdroid to read the ecm and it shows the OS 9381344 which apparently is not an easy OS to find .xdf files for.

a friend told me to write it with OS 12202088. i have the .xdf and .bin for 12202088 and changed a few things with tunepro. VAT off , rearend ratio, speed limiter.

before i overwrite the ecm has anyone else done this OS overwrite and were there any issues or complications i should know about?

[B52Bombardier1]

Hello,

Yes, its been done many times but I have a few questions for you.

Is this your daily driver vehicle?

Do you have a spare PCM upon which to do the OS change?

Bench harness or flashing in the vehicle? Bench harness for me.

Have you made a file copy of your current OS?

Rick

[Oso]

It’s my DD but I have another. Don’t have a spare but my buddy has a wrecking yard so it’s a phone call away. In the truck flashing and I made a copy of the original just in case.

[B52Bombardier1]

Reading your PCM with it installed in the truck is zero risk. Writing an OS to it with it installed in the vehicle carries moderate risk. This is due to other modules on the bus causing noise and chatter that can interfere with writing. A falling 12 volt battery voltage in the vehicle is always risky.

Doing this in the vehicle can turn your PCM into a wheel chock. They also make nice book ends on the shelf and can be a real conversation starter on the kitchen table . . . mostly from my wife telling me to clean that mess up.

Rick

[Oso]

If it makes it safer I can pull the ecm and make a bench harness. I have a good power supply.

How do I get it to write the new OS?

[B52Bombardier1]

You need a device that connects to the OBD2 connector. I use a Bluetooth OBDLink MX device for hardware and either "LS Droid" or "PCM Hammer" to do the writing. Tuner Pro RT for me is only for editing the BIN. My bench harness has a three amp Radio Shack power supply for a perfect 13.8 volts delivered to the PCM.

If you have already made a copy of your OS, it sounds to me like you already have the capability to write an OS. Or did somebody do that for you?

Rick

[Oso]

Hey Rick. Last night I cloned the 9381344 os and then rewrote it to 12208323 using pcmhammer and obdlink lx. Funny story and really close call but as I was cloning it I had a power failure of some type and actually bricked the ecm while using lsdroid for the clone.
I was able to unbrick it with pcmhammer by rewriting it to the original 9381344 after a very tense pucker time. It started and I breathed easy. I then did the clone with pcmhammer and rewrote it to the new OS.
Went to start it and it would hit and die.
Remembered I didn’t remove the vats.
A quick hop into tunerproRT and Vats turned off with a reflash.
Held my breath and turned the key and joy when it fired and ran smoothly.
Test drive and the trans shifting felt spongy at best.
Came back and found “performance” mode settings listed so I copied those to the “normal” trans settings and reflashed. Text drive and it shifts hard again although it holds first a tad longer than I’d like. I can change that.
Continuing in next post.

[Oso]

sorry was on my phone and it was hard to post...

changed the VIN and reflash but noticed i had a warning light for charging.. but using the indash gauge i could see i was 14.2v charging which was confirmed with multi meter... but i searched and found a similar issue with others and the fix for it *(which is replacing a plug on the alternator and pinning in a wire from the ecm to the alternator because the older models such as mind didn't come with that particular wire). so i turned the DTC off using tunerpro and all good until i can get pins to do it properly and to also pin in the electric fans so i don't have to use the toggle switches anymore.

i will say all the knowledge and quick learning is due to using the search function here. 2 friends off facebook who are extremely patient and helped me by text. and the excellent tunerpro and pcmhammer software.

i cannot praise this site enough and i cannot praise the programmers of tunerpro and pcmhammer enough. these guys are literal genius and i truly appreciate their hard work. the fact i brought a bricked ecm back to life with their program speaks mountains to their hard work and a am in awe of them

i am now reading the excellent how to on beginning tuning written by eagle mark i believe..

[Oso]

i also forgot to say... the truck runs excellently... pulls hard and i hope using tunerpro and the knowledge base here i can tune it up and make
more power.

one other thought... it really needs to be stressed in the how to that you are unable to rewrite or overwrite a ecu unless it has been cloned. once it's cloned the rewrite was easy to get started.

and to answer your question... i read... i re-read.. i search endlessly till i find what i am looking for.. my 2 buddies answered questions also but searching here i found the answers i was looking for...