: How to manually trigger Manual Mode / Performance Mode shifting on LT1 powered cars

05-25-07, 12:32 PM
I have been wanting to be able to have multiple shift patterns on my ride, and I would like to be able to setup a economy/normal shift mode, a performance mode and a towing mode. Note. This might work on other 4L60E powered cars, but I do not have the specific info on them at this time, so I can't help right now. I do have the info for the 99-00 OBS (Old Body Style) Escalade and will post that info later.

A little background:
We have 4 shift modes on the LT1 PCM (94-95).

1. Normal Mode - This is your mode that is default when you start the car and you are in D4/OD mode (Overdrive).
2. Manual Mode - This is triggered if you have the shifter in D2 or D1.
3. Performance Mode - This is triggered if you have a performance mode switch and you have started the car and flipped the performance mode switch (F and Y car only)
4. Cruise Mode - This mode is active when you have cruise control on

Ok, what can we do?

1. We need to add the Peformance Switch modification that Scott Mueller has written up.

Adding an automatic transmission "Performance Mode" switch to B/D/F/Y vehicles with an LT1 engine and a 4L60E (RPO M30) automatic transmission:

Copr. 2005 by: Scott Mueller <mailto:scottmueller@compuserve.com>
Photographs courtesy of Jay Gottlieb.

1994 and 1995 Pontiac Firebirds equipped with the LT1 engine and a 4L60E (RPO M30) automatic transmission also came with a very cool feature, a transmission "performance mode" switch (button) mounted in the center console. The switch is labeled "Transmission - Perform" (the lettering is backlit in red), and functions like an electronic on-demand shift kit. When in performance mode the shifts are firmer and upshifts are delayed so they occur at higher engine rpms.

The switch is a simple momentary contact push-button switch which is wired to the PCM and mounted in an attractive gray bezel. There were actually two switches available, one has two buttons, a "Transmission - Perform" button and a "Traction Control" (RPO NW9) button, while the other has only the "Transmission - Perform" (M30 w/o NW9) button. It is the latter one you would want when retrofitting to any vehicle without traction control. Note that 6cyl Firebird models also had a similar switch, but it was used to activate 2nd gear start mode instead and of course had different labeling.

This button can be easily installed and made functional in any '94-'97 LT1 equipped vehicle (including the B-car Impala/Caprice), provided you are using either the '94-'95 F-car PCM or you have the performance mode shift subroutine installed in your existing PCM by somebody like Ed Wright of Fastchip <http://www.fastchip.com>. For example this button could easily be added to a '95 Camaro with no PCM changes whatsoever, as all F-cars for a given year use the same PCM calibration (although the Camaro never included the performance mode switch). It could also be added to any '94-'96 Impala or Caprice, provided you had Fastchip install the proper subroutine in your PCM. Wiring the switch is simple, there are three connections made under the dash and two wires that run to the PCM.

The performance mode switch enables the selection of a more aggressive shift pattern when operating between 40% to 100% throttle. When performance mode is selected, the B+ performance mode signal from the PCM is momentarily grounded (the PCM sees the signal go to 0 volts). The PCM then enters performance mode and turns on the performance mode indicator LED inside the switch button. While in performance mode, shifts are firmer and delayed 1-3 mph on upshifts as well as advanced 1-3 mph on downshifts. Normal mode is selected by momentarily pressing the performance mode switch button again. Normal mode is also the default anytime the ignition switch is cycled.

If you have the 13 photos (PM01.JPG through PM13.JPG, thanks to Jay Gottlieb) that go along with this article, they show the installation process as well as the completed result.
(NOTE: I don't have the photos, I will talk to Scott about getting them, but they are lost on the net right now--Tom, N0DIH)

To install and connect the performance mode switch you will need:

Part no. Description Qty.
10195551 '94-'95 Pontiac Perf. Mode switch (M30 w/o NW9) 1
12064769 10-way female Metri-Pack 150 connector housing 1
12047767 Female Metri-Pack 150 terminals 5
12084913 Female PCM connector terminals 2
12051375 1/4-inch wire conduit (15-feet) 1

If you can't get the individual 10-way Metri-Pack 150 female connector housing
and terminals, then instead you can purchase a pigtail instead:

Part no. Description Qty.
12101762 10-way female Metri-Pack 150 connector pigtail 1

In addition to the parts above, you will need three approx. 6-foot lengths and two approx. 20-foot lengths of 22 gauge wire, plus a number of nylon zip ties to secure the wiring.

Although I'll tell you everything you need to know in this write-up, for further reference you will find the wiring diagram for the switch on pages 6E3-C8-12 and 8A-39-2 of the '95 F-car service manual. The connector pinout is shown on page 8A-202-21.

The 10-way connector for the switch is wired as follows:

Terminal Signal
Position Description
A PCM A15 (red connector) Perf. Mode LED indicator driver
B Interior lights dimming
F Ground
G B+ Hot in Run (ign. switch)
K PCM C13 (gray/clear connector) Perf Mode switch signal

The connector terminal positions facing the connector female end with the retainer lock on top are shown in the following diagram (view in a monospace font):
| |
_| K J H G F |
| A B C D E |

Note that only 5 of the 10-way connector terminal positions are used.

Operation is as follows: When the performance mode switch button is pressed, it internally connects terminal K (PCM C13) to F (ground), which tells the PCM to enter performance mode. The PCM will then ground terminal A (PCM A15) which causes the LED inside the button to illuminate indicating performance mode has been selected. Power for the LED is provided on terminal G (B+ Hot in Run). Terminal B (Interior lights dimming) provides power for the red backlight inside the switch circuit.


Locate a position where you will install the switch. Remove the console cover if you intend to install the switch there, or if you wish to put it in the dash, remove whatever dash piece it will be installed in.

Get three 6-foot lengths of 22 gauge wire and crimp Metri-Pack 150 terminals on one end of each of the wires. Although specific colors are not required, if you are a perfectionist like I am, they would have to be GRY (gray), BLK/WHT (black with a white tracer), and BRN (brown) because that's exactly what the factory used. <g>

Insert the terminal ends you just crimped into the B, F, and G positions (respectively) in the 10-way connector. Route the wires through the place you intend to install the switch (for example the floor console) to underneath the left side of the dashboard. Splice or connect the wires to the appropriate connections under the dash such that terminal B is wired to the vehicle interior lights circuit, terminal F to ground, and terminal G to an ignition (hot in run) source. Normally GM vehicles use GRY for interior lights, BLK/WHT for ground, and BRN for ignition (hot in run) connections, so you you can probably look for any wires of those colors under the dash and splice to them. Be sure to verify the circuit you are connecting to before splicing.

Next get two 20-foot lengths of 22 ga. wire. Although it's not mandatory to use specific colors, the factory used DK BLU (dark blue) and LT BLU (light blue) for these. Crimp Metri-Pack 150 terminals on one end of each of these wires and insert them into the A and K terminal positions (respectively) of the 10-way connector. Then route these wires to underneath the left side of the dashboard, and then through the firewall and over to the PCM.

On the B-cars, there is a convenient oval shaped hole with a rubber plug in it just behind the LH front wheel arch, which will allow you to route these wires through the firewall without drilling any holes. Get the wires positioned and tied down under the hood, it is recommended you either insert them in existing harness loom, or use the 1/4-inch loom I listed above to protect them. Make sure the wires are tied down and secure all the way to the PCM.

Trim the wires to length and crimp on the PCM connector female terminals. Then insert the PCM terminal ends into the PCM connectors at the A15 (DK BLU wire from terminal A on the 10-way switch connector) and C13 (LT BLU wire from terminal K on the 10-way switch connector) respectively.

Finally cut a hole matching the backside of the switch in the console or dash area you intend to mount the switch, then plug the 10-way connector into the switch and snap the switch into place. That completes the wiring!

If you are not running a '94-'95 F-car PCM, then you will want to talk to your favorite PCM reprogrammer to have the performance shift subroutine installed in your PCM. Ed Wright of <http://www.fastchip.com> can do this as well as customize other aspects of your PCM. Once the PCM with the proper subroutine is installed in the PCM, the button will be fully functional.

I had this switch installed and functional in the center console of my Impala since early '96 (using an F-car PCM calibration). It gives all the effects of having a shift kit installed when activated, and yet with the press of a button one can return to normal softer shifting. All in all this is another great "factory" mod one can add to their car! Scott.

05-26-07, 09:45 PM
More to follow, just got to finish writing up the second part....

09-30-07, 10:52 PM
My question is how do I install the "performance mode shift subroutine"? I'm currently driving a 96 B-Body with a revision E OBD1 PCM from a 95 B-Body. I'm trying to become as self sufficient with this PCM programming stuff as possible (primarily to further my own education). I'm currently using the C.A.T.S Tuner software; I can't seem to find the relevant option to put a check next to. :D

I've hooked up all my wires (checked over them several times with a multimeter) and I still have no joy. For testing I currently have no switch or led hooked up. What I'm seeing is that when I test between A15 and hot I see 12V, whether or not I've grounded C13 (all this with the key in the run position).

I've determined that my PCM simply isn't programmed for "Performance Mode" though the evidence provided by Scott's article indicates that it does support it. Is it possible for me to program my PCM for this myself or am I going to have to farm this out?

09-30-07, 11:28 PM
The PCM likely isn't programmed for it, sometimes you see something in there, but I don't think most are truly setup.

Scott used a 95 Z28 w/3.23 program, so his was setup (they didn't have tuner programs for the LT1 then!).

You can use TunerCat ($70+$20 for the $EE definition file) and then get a cable from AKMCables.com or PCMPerformance.com and do it yourself. If you have never tuned before it is going to be quite overwhelming, but not impossible. I have done mine sooooo many times I don't bat an eye at whatever I want to do.

I do my own tuning, and have mine setup, but not added the wiring (I have a Fleetwood, so it is not so easy to do and look factory....)

Shoot me an email at n0dih (at) t6b.com and we can talk about it.

10-01-07, 12:04 PM
Thanks for replying to my post. Per your point about keeping the factory look: I'm driving a Buick Roadmaster (I know I'm a heretic for posting in a Cadillac forum). I intend on mounting the toggle switch where the ash tray is. That is, removing the ash tray and fabricating a plate to sit in it's place. That way, no permanent modifications.

Back to the PCM modification; the article that originally turned me on to this project can be found here (http://www.trifectaperformance.com/tech/LT1TransmissionPerformanceMode.htm).

Both this article and Scott's indicate that I meet the prerequisites for this mod. In my PCM all of the performance tables are populated. That doesn't seem to matter though because the feature isn't enabled in my PCM. This seems to be corroborated by Scott's post indicating that I need to have the "performance mode shift subroutine installed" in my PCM. Said website corroborates this by saying that I need to have my PCM "professionally programmed to enable this feature".

I've just started tunning with TunerCAT. I'm amazed at the difference that can be made by modifying all these various tables. I can't for the life of me though figure out how to enable performance shift mode. Any help appreciated.

10-01-07, 01:19 PM
You don't need to do anything to the tune to "enable" it, other than populate the fields needed. The hardware handles the change of programs from normal to performance. And manual 2nd triggers Manual Mode (that is, putting gear lever in 2nd).....

Shoot me an email and we can talk about what you need tune wise.

11-13-07, 12:01 PM
All PCM codes found in LT1 powered vehicles have both normal and performance shift tables -- already populated. That goes for both OBD1 and OBD2 -- doesn't matter.

Did you resolve your issue? Keep the discussion here. Inquiring minds want to know.:thumbsup:

11-13-07, 12:10 PM
They are populated, but not sure how "good" they are.

What I want to be able to do it have 3 shift tables easily accessed.

Normal Mode
Performance Mode (switch wired up as above)
Manual Mode (this is trigged by the shift lever moved to the D2 position) giving me 2nd, 3rd and 4th only, losing 1st.

The Manual Mode D2 is trigged by the hydraulic fluid pushing on the transducer (pressure switch) inside the trans. There is no PRNDL switch like the older cars had. So you would have to wire into that circuit. This would let you use a toggle switch for say second gear start so you don't need to grab the shift lever, then you (for economy or bad weather reasons) just flip it on and it would shift normally, sans first (if you have it setup, 95-up cars got 2nd start disabled via SWITCH setting in the PCM code, not by fixing the tables, which essentially disabled the ability to use the Manual Shift table. As the trans in Manual Low does trigger manual mode, but the trans manually shifted there FORCES 1st gear, overriding the PCM desires.

So, yes, 3 shift tables are possible, it would take a tuner to setup if you previously have had GM disable the second gear start feature. I like 2nd gear start in bad weather. With 3.42's, it is almost mandatory! I have 3.08's and posi this year, we'll see if it is better, I will try to get my 3.42 axle back in with the posi, but that isn't happening till we get this move next week finished and I get some $$ for the parts I need to set it up.

11-13-07, 08:38 PM
Gaining the infamous 2nd gear start is just as simple as setting your gear selector in 1st OR 2nd and setting the values in the Manual table for the 1-2 and 2-1 to "0" across the board. Done.:thumbsup:

Wiring the PCM for the addition of a toggle switch, like that found in the Firehawks is another story. I didn't read that whole post listed above, but I'm sure that if it's from Scott Meuler, it's probably pretty close, if not right on. Both the "Normal" and "Performance" mode tables can be manipulated easily in the program using LT1 Edit. It's a breeze. I had one customer reverse the "Performance" mode, making it the short shifting, softer one so that his wife wouldn't abuse the car. Funny huh?:canttalk:

If you're succesful in adding the toggle switch and this ultimately works, please post more. It was always my understanding that this feature only worked in F-Body programs -- not B bodies. The tables are there for sure, but I don't know of anyone who's done it before. Your PCM could be loaded with an F-Body program, but if you have a tach in the car the values will double and then you'll need to deal with that issue.

From having driven a few Firehawks, I know that it is instantaneous. Pretty neat trick. I just used to program my automatics for "Performance" anyway, but to each his own.

Good luck and keep us posted.:alchi:

11-13-07, 10:13 PM
LT1Edit is horribly out of date compared to TunerCat (I wouldn't recommend it to ANYONE). There is a switch setting to turn on/off manual mode when selector is in D2. (I know, I had TunerCat's author dig it up for me...). 1995-up cars (B/D) lost 2nd gear start somewhere in mid 1995 midst a rash of transmission failures due to people starting in second and pulling trailers.

I'll have to get working on it and see what I can come up with.

The PCM in the F and B/D bodies is identical. So it WILL work for performance mode. And has for many people who have done it.

I work on my trans to be more towards perf mode anyway too, can't stand mush shifting.... Mine is a V4P towing car, so it is setup tougher anyway.

11-30-07, 02:19 AM
LT1Edit is horribly out of date compared to TunerCat (I wouldn't recommend it to ANYONE). There is a switch setting to turn on/off manual mode when selector is in D2. (I know, I had TunerCat's author dig it up for me...). 1995-up cars (B/D) lost 2nd gear start somewhere in mid 1995 midst a rash of transmission failures due to people starting in second and pulling trailers.

I'll have to get working on it and see what I can come up with.

The PCM in the F and B/D bodies is identical. So it WILL work for performance mode. And has for many people who have done it.

I work on my trans to be more towards perf mode anyway too, can't stand mush shifting.... Mine is a V4P towing car, so it is setup tougher anyway.

I'd place a wager on performance using my LT1 edit Vs someone else using Tunercat. I think LT1 edit has always had enough parameters for me. I don't know which software came out first, but I personally know the originators of LT1 Edit and they've impressed me for years.

Good luck figuring out what you're doing. Please post when you've had success.

12-11-07, 11:52 PM
What I see improved with TunerCat is updates, new things still being found out and released. The main things are all there. And being VIN Locked, no likey at all. If the price was reasonable, I would be ok with it, but not the prices they charge. To each his own. Hopefully they gave you a lot better deal than the general public gets. I am not bashing them, I just don't feel the price they charge is worth what you get when the competition is 1/3rd to 1/4 the price and unlimited vehicles. They just don't offer anything at all to compete with it. Their business model is WAAAY off.