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98pcm/4l80e question...again

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Old Sep 21, 2007 | 04:33 PM
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Default 98pcm/4l80e question...again

I tried posting this is the automatic transmission section with no luck..so here we go...

I have a Z28 with the 402 in my signature and a 4L80e transmission. The car is a 1998 car so it has a 98 pcm. Well, the engine shop ran into an issue with the pcm. They told me the trans guy messed up some wires and now it would not start, but my tuner and I think they (engine shop) had the ignition on when they unhooked the battery and that messed up the theft system on my PCM.

It had a temporary mail order tune on it from PCMforless and as far as I know they do NOT lock their PCMs. Well, regardless, I had to get a new PCM because they 98 one I had was locked. So, I went ahead and got a 99pcm because I was told the 98 pcms will not control the shift sequences on the 4L80e.

The 99pcm is going to be a pain to install. My electrician told me he would look into using a 99 wiring harness to perform the swap, the only other option is to switch out all the pins in the PCMs to match up (out of 80+ pins only 2 are in the same location on the 98-99 PCMs). Either option is going to be extremely time consuming and not cheap. This is my only car right now and I am in a bind.

So, here is my question:
Is it possible to buy another 98 PCM and have the tuner tune it so everything works fine EXCEPT the shift sequences? The transmission guy rigged up some switches so I can manually shift the 4L80e since the 98pcm I had would not shift it. This would be a temporary fix until I have the money and time to have the 99pcm installed. Will everything work fine discounting the fact that I will have to manually shift it? I need input, I MUST get my car up and running. Thanks everyone
Mitchell
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Old Sep 24, 2007 | 10:03 AM
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Originally Posted by SVT THIS
I tried posting this is the automatic transmission section with no luck..so here we go...

I have a Z28 with the 402 in my signature and a 4L80e transmission. The car is a 1998 car so it has a 98 pcm. Well, the engine shop ran into an issue with the pcm. They told me the trans guy messed up some wires and now it would not start, but my tuner and I think they (engine shop) had the ignition on when they unhooked the battery and that messed up the theft system on my PCM.

It had a temporary mail order tune on it from PCMforless and as far as I know they do NOT lock their PCMs. Well, regardless, I had to get a new PCM because they 98 one I had was locked. So, I went ahead and got a 99pcm because I was told the 98 pcms will not control the shift sequences on the 4L80e.

The 99pcm is going to be a pain to install. My electrician told me he would look into using a 99 wiring harness to perform the swap, the only other option is to switch out all the pins in the PCMs to match up (out of 80+ pins only 2 are in the same location on the 98-99 PCMs). Either option is going to be extremely time consuming and not cheap. This is my only car right now and I am in a bind.

So, here is my question:
Is it possible to buy another 98 PCM and have the tuner tune it so everything works fine EXCEPT the shift sequences? The transmission guy rigged up some switches so I can manually shift the 4L80e since the 98pcm I had would not shift it. This would be a temporary fix until I have the money and time to have the 99pcm installed. Will everything work fine discounting the fact that I will have to manually shift it? I need input, I MUST get my car up and running. Thanks everyone
Mitchell

Mitchell, I believe the computers for 97 and earlier wont except the 4l80e shift strategy but 98 and newer will. I had Charlie Williams at RPM Motors in California convert my pcm he did say it was a pain, but it does work. And Im assuming that you have run the wires for the input speed sensor to the pcm already. Hope this helps, Mason
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