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-   1992-1999 (https://www.gmforum.com/1992-1999-91/)
-   -   Perform Shift and Normal Shift do nothing? (https://www.gmforum.com/1992-1999-91/perform-shift-normal-shift-do-nothing-253823/)

BillBoost37 03-19-2007 07:42 PM

:oops: Sorry..I thought we were talking about the 98's. 92-99's had them .

TrueWildMan 03-19-2007 07:49 PM


Originally Posted by BillBoost37
:oops: Sorry..I thought we were talking about the 98's. 92-99's had them .

D'oh! No, I'm sorry, I thought you were talking to me. LOL :oops: :oops:

I blame the pain-killers!! Again!!

BillBoost37 03-19-2007 07:52 PM

I'll blame the Goose.. ;)

Hans 03-19-2007 08:39 PM

so there is NOT supposed to be any difference on the 98s between the buttons?

willwren 03-19-2007 08:52 PM

There is.

Your PCM defaults to normal mode for a NA car in Performance mode.

Your PCM retards the shifts in economy mode by inducing a resistance (voltage divider circuit to drop the voltage from 5V at the PCM to 2.5V) in order to slightly retard the shift points for greater economy.

I have personally never seen a resistor short across the leads, so I'd say you have a short to ground holding that pin at a constant 5v and preventing the resistor from being introduced into the circuit.

Hans 03-19-2007 09:15 PM


Originally Posted by willwren
There is.

Your PCM defaults to normal mode for a NA car in Performance mode.

Your PCM retards the shifts in economy mode by inducing a resistance (voltage divider circuit to drop the voltage from 5V at the PCM to 2.5V) in order to slightly retard the shift points for greater economy.

I have personally never seen a resistor short across the leads, so I'd say you have a short to ground holding that pin at a constant 5v and preventing the resistor from being introduced into the circuit.

Where is this resistor you speak of? I'm happy to get the dmm with long leads to test while driving or whatever I need to do.


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