I have an 01 C5 which I purchased used. Recently the shop changed out the fuel sensors to resolve intermittent fuel gauge operation. When this did not solve the problem they took the vehicle to a local Chevy shop which attempted to implement a TSB relative to a computer patch which addresses the sensor headache. Unfortunately they were not able to implement the fix.

Their reason was that the computer had been altered and they were unable to get the patch to install with the existing programming. Their solution is to replace the computer to the tune of about $2500.00.

Can the existing computer be reset back to Factory OEM condition?

If so is there a source for the patch that will allow me to install the fix for the fuel gauge?

If there is a DO IT YOURSELF fix what programming unit should I buy?

If this is not a DO IT YOURSELF fix, then is there a shop which will reflash the computer to stock so I can get the TSB implemented?

 

First off dealers are rip offs! Second a new computer cost around 3-4 hundred dollar range. I would buy a PCM and go to a tuner near your area and have them tune your ride it would cost less than half of that. and the computer is easy to replace

 

I believe it has to be programmed by GM the 1st time a new one is installed. Chances are somone did a "custom" tune on it already, that's why the dealer is havng issues. I'd try one more GM dealer, they should be able to get it back to stock, then flash updates into it.

 

I DO UNDERSTAND, my opinion was base on the dealers reaction to his problem. If a tune has locked the PCM then he has to return to that tuner or buy a new PCM. If his PCM has not been locked then the dealer can reflash the PCM back to stock perimeters

 

I agree that it sounds like it was locked by your tuner or the previous owner of the car, via their tuner. The PCM is fairly cheap and it should only cost about an hour of labor to reprogram it. Now putting it in might cost additional time but should be fairly simple and quick.

 

If you go to that auction site you will find used PCMs for under $100.00 programmed for your specific vehicle using your VIN.

 

I recently took my 2003 to a tuner. Before that however I purchased a spare pcm from a vendor on ebay. He used my vin # to program it to factory specifications and all my options. When it arrived I removed my original pcm and kept it with the factory tune and installed the replacement in my car. I went through the relearn steps and the car started right up. The tuner did his thing and added his tune and now I still have a spare with all factory specs..It only cost about 100 dollars for the relacement pcm.

 

I was unaware that tuner could lock out a computer. I know a tuner Diablo, HP, Hypertec.... is locked out when you tune your vehicle with it but never have I heard a computer being locked out. I think they are trying to stick one in ya for sure, but I don't no that for a fact.

 

By tuner, they are talking about a person who installs a custom tune on your PCM using programs like HP Tuners, EFI Live, LS1 Edit, etc. These tunes can be locked or password protected. Once they are locked no changes can be made such as setting them back to stock.The practice has pretty much been abandoned now but in years past was pretty common. If your tune has been locked this way you have three choices; live with your tune, find the original tuner and pay him to unlock your tune or get another PCM.

 

Ya I was just unaware that anybody was "locking up" a computer when they tuned it. I did my own with LS1 edit and in 2004 and don't recall seeing option to lock it. It still seems to me the dealer could reflash it since they are not using the same software a tuner was. Just flash it with a complete factory tune for what ever year/model car he has.

 

I started skulking around and located the PCM new for approximately$250.00 from a dealer. That was good news. The bad news was the shop could not/would not program the new PCM without the Vette being in their shop.

I looked on the auction place, noted there were PCM's being sold outright for about $90.00 and shipped after being programmed with the info based on the VIN. Will likely give that a try and see where it leads. Hopefully it does not wind up being locked.

Again thanks for the tips, hints and steering.

 

[QUOTE=LVZO6;1571996791]It still seems to me the dealer could reflash it since they are not using the same software a tuner was. QUOTE]

I am not sure how the PCM unit is locked after programming but many microcontrollers used in other similar devices allow the option of setting a "Security Bit" which invokes a password challenge the next time an attempt is made to access the programmable features. Fortunately the PCM does not use a microcontroller that actually has a 'fuse' which is deliberately blown following the initial programming that blocks any further attempts to program or reprogram the device, making the device forever ie; the fuse is inside the microcontroller and there is no economical way to 'unblow' the fuse.

 

To safely program a new PCM, its best to have the car right there and the place that's doing it, needs to do so with a Tech2. RPO codes, security and so on, all need to go into it before the car will properly work. I've never purchased a PCM from an online source as such that promises to program it in advance but there should still be a security issue to resolve once its in your hands, installed and so on. The BCM and PCM share a hidden password between them therefore there is a learn mode for that process which takes a little time to accomplish.

 

Sorry but this is BS, if you have a locked PCM it can only be retuned by reflashing it with a stock tune first.
Years ago I had a locked tune from a big name tuner in Ok. and my tuner loaded a stock tune and started over again from scratch.
Once it's locked you just can't change one small part of it, it's all or nothing!

 

Most reflash processes start by copying the stock tune to a backup. People that sell cars and don't return them to stock or provide the flash tool and stock file with them should be drug behind a truck down a gravel road.

That same person used up one of their credits or locked the flash tool when they did that too so they didn't help you or themselves.

 

I have ordered an ECM which is advertised to be ready out of the box for installation as I understand it. They use the VIN # to set the new box up.

However in reading other posts in the forum it appears there may be a problem waiting to hit me in the face and that is the handshaking between the BCM and the ECM. In some parts of the forum there is reference to attaching a programming box to set up communciations between the two modules that involve security features.

Will a new box programmed with the factory data set and revisions work out of the shipping container or am I going to be in the business of programming values to establish communications between the two boxes?

 

From one of Bill Curlee's post:
---------------------------------------------------------
The BCM and PCM are NOT plug and play modules and must be programmed using the tech II/ There is an Emergency Sync procedure that you can use if you have to install a BCm on the road with out a TECH II:
-----------------------------------------------------------
BCM/PCM RELEARN PROCEDURE


You will need to conduct the PCM/BCM relearn process. This matches their handshake ID's and allows them to talk to each other.

Do this before you worry about VATS issues:

1. Turn on the key for 11 minutes.
2 Turn off the key for 30 seconds.
3. Repeat 1&2 two more times.
4. Turn on the key for 30 seconds.

The car should start and run with the new BCM. Good luck and report back on your progress.
Shirl
SD Racing Enterprises
Aguila, AZ
Coutersy of MrEracer


This will sync the PCM to the New BCM but all of your RPO options will not be retained. You will need a TECH II to program them into the new BCM.


If that doesnt work, Unplug all un necessary modules ie: Door Modules, Drivers seat Module, HVAC module, RFA Module, etc and see if the issue goes away The ONLY modules that you need to start the car is BCM and PCM.

If you isolate all those things, it will tell you if some other module is causing the issue:

BC