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-   -   Adding Performance Shift Buttons for Those Without! (

CDecker 07-19-2002 04:33 PM

Adding Performance Shift Buttons for Those Without!
Ok guys, trying to figure this out, maybe some of you out there have tried it or know an easy way to do it. SSEi95 and I were talking on IRC the other day, and someone was talking about how in 2001-2002, GM Removed the "Performance Shift Button" that was on the transmission gear selector handle in their grand prixs. As most of you know, some bonnevilles got this same option (the top 2 buttons in the center console to the left of the shifter), mainly those of you with SSEi's (prior to 2000).

Anyways, one of the grand prix guys decided to study his factory service manual one day, and find out exactly how to get the button back. Like him, I would be very interested in adding the 2 buttons to my '95 SSE, which would allow me to select between performance shift and normal shift. Since I recently had to pull my console and dash out to fix my little climate control problem I was having, I noticed that there is no un-used connecter just hanging out inside the center console waiting to be plugged in (I wish It coulda been that easy). I'm sure I could find a replacement panel in the salvage yard with all the buttons in it, but then that leads us to the question of where is it going to plug into, and what wires do we need to find....

Here is the post on clubgp where CW wired his, giving step-by-step instructions, however it is of course very different from their GP's to our Bonnevilles.

He mentions in this site that you must have the aftermarket PCM. I think this is due to the fact that since GM completely removed the button from them all together (SE's, GT's and GTP's), they didnt even program it into the PCM. I'm thinking that since it was available for sure in a '95 SSEi, since SSEi95 confirmed it for me because he has them, and I dont have them in my '95 SSE, I'm wondering if its just a matter of finding the wires, and hopefully its already in the computer...

The only other thing that could pose a problem, is that someone thought even the Series I supercharged motors had an electronically controlled transmission (even in the earlier models like 93, 94, etc..) and I'm not sure if this is true. I know I have the 4T60E in my SSE, and I thought that all bonnevilles prior to 97 had this same tranny, supercharged or not?? SSEi95 and I are in the process of comparing wiring and vacuum lines that are physically going into the transmission, so we will have to post some more info once we come to a conslusion on wether we think they are different or not.

If anyone else has tried this or has any info, please share!! We are usually talking about projects like this in the clubs new IRC chatroom (see skza's post in the general info section), so stop in and talk!!

Thanks! 8)

Teuobk 07-20-2002 12:13 AM


I'll take a gander in my service manual to see if it's something simple, such as a grounded wire.

Teuobk 07-20-2002 12:28 AM

My post reminded me of something...

While at the W-Body gathering, I met Brian89GP. He showed me a neat gadget that he designed which allows complete control of the transmission. By splicing into the control lines, his device can command immediate gear shifts. A PIC microcontroller watches over everything to make sure you don't do something stupid, but other than that, you have full manual control. It's kinda like the ultimate performance shift mod.

Maybe you can say more about it, Brian?

csprague 07-20-2002 10:45 AM

All 91-96 Bonnevilles used the 4T60-E. All 97-present Bonnevilles use the 4T65-E. Both are electronically controlled transmissions (hence the "E"). You can check out your tranny model by simply going under the car and looking at the pan.

I talked to Deathrat about this a while back, he thought the code was not in the non-supercharged PCMs. I am leary about splicing into PCM wires, and I think I'd rather get a chip which will probably do the same thing. But good luck on finding out any more info on this.

Teuobk 07-20-2002 06:38 PM

I had some spare time, the service manual, and some electronic parts today, so I decided to tackle the problem.

Don't do this if you're not competent, applying this information might destroy something, I'm not liable for anything you do, and all other usual disclaimers apply.

First, I dug around the service manual to see exactly what that "Performance/Normal" switch does. Turns out that (on 1992-1995 models) pressing "Performance" puts a 348-ohm resistance between the diagnostic pin on the DLC and ground. Pressing "Normal" removes this resistance (open circuit). Normally, there is a 5v potential between the diagnostic pin and ground; adding the resistance changes this to a 2.5v difference. As a side note, grounding the diagnostic pin will put the car in diagnostic mode, allowing you to see any DTC codes stored in the PCM.

Where does the switch hook into the DLC line? If you pry up the console switches (for traction control, electronic struts, etc), you'll find one or two connectors. I think you have two if you have electronic front struts and one if you don't. Disonnect the bigger of the two connectors (eight pins). Around the bottom of the connector, where the wires enter, you'll see eight letters, A - H. We're interested in G and H.

When "Performance" is selected, a 348-ohm resistance is placed between G and H. When "Normal" is selected, the resistance is removed. I decided to emulate the switch, so I looked for something of the correct resistance. Now, 348 ohms is not a common resistance. The closest you can get with a standard resistor is 360 ohms, but I didn't have any of those handy, so I wired a 330 and two 10s in series. My multimeter confirmed that this combination was about 350 ohms.

I went back to the car, connected the 350 ohm resistance between G and H, and went for a drive. According to the manual, performance mode makes the shift points higher and (somehow) provides more available torque in first and seconds gears. I found a nice road and made several "spirited" runs :wink: I didn't notice any difference. I was expecting a large or at least noticable change, so I thought that perhaps I forgot what "normal" felt like. While driving, I pulled the resistance, then made the runs again. It felt exactly the same. I put it back in. No change. Disappointed, I returned home.

So what happened? I think that there are two possibilities. First, the mod might have been working. Although I accelerated a bit faster than normal, I didn't really get on it (e.g., I didn't go to redline through the gears). The other possibility is that my PCM is programmed to ignore "performance" mode. I'm not sure how to test that.

Maybe someone else can try the mod? It's non-destructive, can be done in literally minutes, and might cost at most $2.00 . Let me know if you need help!

SSEi95 07-20-2002 07:05 PM

I have the perfomance switch option. The main noticeable diffence I see is the shift points when completely floored. In normal mode it will shift somewhere around 4500RPM. In performance mode it will shift in the yellow at 5400 RPM.

As far as the 1st and 2nd gear torque, I really haven't ever noticed much diffence in it. Then again, I didn't even know it was supposed to change that too so I never payed attention for torque differences.

CDecker 07-20-2002 11:43 PM

Wow Teuobk, nice job giving this a shot!! I'm going to head to the salvage yard monday, and see if I can find a FULL switch pod from a SSEi. I was looking through my factory service manual, and found exactly what you are talking about. I also noticed that it looks like all of this is controlled through the PCM. I'm wondering if our PCM's even have the codes in them to make it work. I also noticed that cmong off the switch (Book 2) there is a Light Blue wire that seems to run to the PCM. Since the book gives the exact location on the PCM connector, I was going to check and see if the wire even existed.

This is where I am confused with what wires you were connecting teuobk? I know what connecters you are talking about, I was looking at them when I tore my console/dash out. Your right, I do have to, and the one in the middle is bigger than the one for the auto suspension I think. They are still seperate however, both have wire wrapped in tape, that eventually all follow into one big harness heading from the center console back up into the dash. Are you thinking that all of our cars are already pre-wired for this switch, and all we gotta do is just wire in the switch? Man that would be sweet... What do you think puts the 348-ohm resistance on the wire? The actual switch itself (when its there)??

Just curious, but it sounds like we might be able to figure this out!! I'm definetely willing to give it a shot on my car... I mean, your talking to someone who just completely tore his dashboard out a week ago to fix a climate control problem, and then put it all back together in working condition, with the problem fixed. If theres a mod like this out there for us to try, count me in!!

I might do some more playing tomorrow... Made my own custom CAI today with my stock air box, keeping my $70 OE drop in replacement K&N Filter I bought a couple years ago. Also I removed the honeycomb throttle body screen like skza suggested. Turned out great, and I actually noticed a nice improvement.

Anyways, keep us posted, and I'll do the same... 8)

Teuobk 07-21-2002 12:10 AM


Originally Posted by Terminator
Are you thinking that all of our cars are already pre-wired for this switch, and all we gotta do is just wire in the switch? Man that would be sweet... What do you think puts the 348-ohm resistance on the wire? The actual switch itself (when its there)??

Yep, it appears that way. The line is, without a doubt, the correct one. From the schematic, it appears that the switch puts the 348-ohm resistance on the wire, which happens to be the correct value to halve the voltage. I imagine (but have not tried) that a 2.5v LED would accomplish the same thing.

Yeah, try it out with the junkyard switch. It should hook up with no problems.

Let us know!

CDecker 07-21-2002 11:09 AM

What color are the wires (G and H)?? I'm gonna go open up the center console today and take a look at the wiring again for those switches.. I dont have the manual right here, its out in the garage, but I think the correct wires going inot the switch were green and black maybe?? and then coming out were lt blue and black? Not sure on those colors.. What did you have to do to find the wires that you put the ohms on? Pry back some electrical tape and there they were just cut off?

Well, out to mess around with this thing.... I'll check and pist more later...

Thanks! 8)

DeathRat 07-21-2002 11:41 AM

My question is: Can this be done to SE's? Is the wiring harness the same regardless of what model it is (IE: SE/SSE/SSEi)? Would I notice an improved shift?

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