Special K

I replaced my PCM the other day and kept the original to put back in for trips back to the dealers. After removing the passenger side front tire and the access panel inside the wheel well the TAC & PCM are exposed. The only difficult part of the whole deal are the back mounting screws. You have to be a contortionist to get to these. Remove the TAC module (2 screws) and then remove the two connectors from the TAC. Once this is out of the way, remove the two connectors from the PCM. These are self extracting connectors that will back out when you turn the mounting screw. Next, loosen the rear mounting screw in the PCM bracket, but don't remove it. Remove the two front mounting screws from the bracket. The PCM will now slide out towards curbside. Reverse this procedure to install but don't tighten the rear PCM mounting screw and do not install the rear mounting screw for the TAC. This will make the next removal much easier. I just used a nylon tie wrap to secure the back of these modules. It is not necessary to disconnect the battery or any fuses to perform this change.
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[Modified by Korreck, 2:02 PM 6/16/2003]


[Modified by Korreck, 2:03 PM 6/16/2003]


[Modified by Korreck, 2:04 PM 6/16/2003]

1999 White C5 Coupe

Korreck,

Why would you replace the PCM and keep the original for a return trip to the dealer?

Special K

Don't want any hassles over the 3 yr. warranty. I'll also use the original when I want more programming done on the modified PCM.

Bob

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minivette

Disconnecting the battery is the absolute first thing you should do when working on your car, especially electrical.

Special K

There are not any exposed connector pins. There's no reason to dis-connect the battery. If it makes you feel better, do it. I will also say there's no mention of dis-connecting the battery in the service manual.
:flag

Godspeed

If you buy a personal copy of LS1 Edit you can save your original PCM with it. You can then tune the car (or have it tuned) and save the new tunes as well. If you need to go back to the dealership simply put the stock program back in the PCM. When the trip to the dealer is over put the good tune back in.

Special K

That would work! I prefer to have Lyndon at Westers Garage do my tuning, so I opted to keep the original PCM. Two reasons: 1. I'm not a tuner. 2. Don't have a laptop. 3. Yeh, I know I said two reasons, so I'll quit. Thanks for the input. I do have a question. Why don't we have a 'Save the Wave' icon to put on the end of our posts?
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[Modified by Korreck, 2:54 PM 6/17/2003]

minivette

LOL... whatever. :rolleyes:

WhiteC5Vette

First rule in electrical engineering is disconnect the power source before disconnecting connectors to surge sensitive devices such as modules (which the PCM is). Anytime you disconnect a connector with power applied, you stand a chance of causing a power surge to the device. That, and just guess what happens if you accidentally short a wire against a metal ground object, due to you scrapping off the plastic insulation? :yesnod: (Even if the GM Service Manual does not state this, I bet GM won't pay for the PCM if you cause a fry it.) But it's your PCM, won't cost me a cent, if it is destroyed .:nonod:
Second rule is never work on the high power side of an electric vehicle while holding on to the frame with your other hand. :lolg:

Special K

Sir, with all due respect, dis-connect the battery if you will feel better. These are female connectors and it would be impossible to have arcing or contact . If these were male connectors, different story. When you can come up with a valid reason for dis-connecting the battery, let me know. Right now, it appears to be your personal preference. It's still not necessary. By the way, I'm a avionics engineer. What's that first rule again??????????
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minivette

[Modified by minivette, 9:37 PM 6/17/2003]

EWill3rd

If you remove the screw in the bottom of the fender and then use a long extension and a magnetic socket, you can remove the screw about half way up near the door jamb. You can see this with a flashlight, inside the fender looking past the TAC and PCM. This will let you pull the fender out slightly and give you a whole lot of room to get to the back screws on the TAC and PCM brackets.
That way you won't throw your shoulder out "contorting" yourself.


It should be noted that if you replace the PCM with a new one, it won't run until it is programmed. (I know what you are doing but that is for other folks)




[Modified by EWill3rd, 8:03 PM 6/18/2003]

Special K

Now you tell me. You can bet I won't forget that. The tie wrap works well but it does look a little tacky. Good thing no one can see it. Thanks for the info.

Bob

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