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I'm trying to add some finishing touches to my custom dash for my 85 TransAM and I wanted to add a small display to show the current gear.
I have a B&M megashifter but lost the gear indicator piece a while back and it wasn't useful anyway because my car is right hand drive and the display was on the wrong side anyway.
I have the gear selector/neutral safety switch attached to the 4L60E with the 7 wire position switch and 4 pin range switch, but it's not the most dependable circuit, and there's a good chance it's stuffed, and can't be removed/replaced without removing the transmission from the tunnel.
That said, if it's possible to wire this directly from the 4L60E connector, this would be preferable, as one less part I have to worry about.
Based on a post, I found the combination of open/grounds from a guy that made exactly what I'm after, but the post was 10+ years old and the link to the wiring diagram was expired.
Looking at it, you can determine the current gear from the 4 signal wire states below:
Signals that come from the 4way wires from the trans.
Wire Gear: Park Rev. Ntrl. O.D. Drive 2nd 1st Signal A GND GND Open Open GND GND Open Signal B Open GND GND GND GND Open Open Signal C Open Open Open GND GND GND GND Signal D GND Open GND Open GND Open GND
My understand of this, is that when the car is in Park, signal wires A & D will have a ground signal, and B & C will be open (no signal) is this correct?
There was some talk of NAND gates but I haven't looked into this yet, I was hoping someone had already done this and had the info / wiring diagrams available.
I've read a little about NAND gates and get the general idea of how they work, in that you can have logic circuits that are either complete or incomplete to get to a result, so I need either a 4 bit decoder, or a tandem 2 bit decoder to make it work.
I'm dabble in electronics but never really anything on the build your own board or circuit from scratch, so my knowledge on this is limited to a resistor.
Has anyone built something similar to this that I could go off?
Without understanding the NAND gate componentry (seems to be like an ICC or group of them) I was thinking of trying it old school and using a series of relays and diodes to prevent one from triggering the other.
The problem with that is that 3rd requires a ground from all four signal wires, so not sure yet how to isolate that from tripping all the others:
Also here is the logic diagram for the decoder, again no idea how this translates to physical hardware to solder together but, "well....there you have it." (-J Goldblum)
3 more coffees later and the 3rd gear could be done with 3 additional relays in line with the first 2 connecting A & B to the common and coil trigger, then that linking to the next relay connected to C for the coil trigger, then that connecting to the next relay common and D for the relay trigger.
It's a hell of a mess to get a set of 7 LEDs to Light up, but doable I guess. Hopefully can find some micro-relays so the module doesn't take up more room than the center console shifter area.
Thanks for the echo chamber to figure it out
Hopefully this helps someone else out if they don't want to shell out $200 for a commerical version of it, or someone better versed in electronic engineering that can create a cheap module.
So you just want to know what range the shifter is in?
A PRND321 indicator
Or do you want a gear counter that shows if you're in 1,2,3,4 as you drive?
So to start I'd like to know the physical position of the shifter, this would be via LED lit up for the particular letter/number.
After that, I'd like to also be able to display the transmissions actual current gear on a small screen, but that isn't critical at this point in time.
From what I've gathered from the inhibitor switch on the 4L60E, the 5/6 pin plug is just the inhibitor and reverse light switch, and the 4 pin uses the logic to tell the physical position of the shifter shaft. (ABCD signal wires)
The PCM gets the transmission current gear from the other wires in the 12-15 pin trans connector directly to the PCM coming in via the active solenoids.
There are 2 ways to get the PRND321 info
You can get it from the neutral safety switch
Or you can get it from the pressure manifold switch
Instead of piles of relays...a simple arduino would be the perfect fit for this kind of project
You could also have it display the current gear as commanded by the solenoids
So you could display that the shifter is in OD...but then also see as the trans is commanded 1-2-3-4
There are 2 ways to get the PRND321 info
You can get it from the neutral safety switch
Or you can get it from the pressure manifold switch
Instead of piles of relays...a simple arduino would be the perfect fit for this kind of project
You could also have it display the current gear as commanded by the solenoids
So you could display that the shifter is in OD...but then also see as the trans is commanded 1-2-3-4
Yeah I've toyed around with Arduino a bit and it would definitely be easier to program a few IF-THEN or CASE statements to cover the variations, I just can't remember off hand how many inputs the UNO or cheap boards take, and if they will work with grounds rather than a voltage.
Again from memory the inputs detect high and low as voltage or no voltage, not a closing of the circuit, so I'd likely need to use a relay board anyway to do it yes?
I know this thread is old, but this is the only thread I found on the internet talking about this type of indicator for the 4L60e.
I have some additional details I used to finish the build out, hope it helps someone looking to do the same.
I used 7 LEDs anode to a common +12 supply. The circuit sinks the cathode of each LED via CD4011 nand gates.
The 3 drive gear uses a cd4002 dual quad input nor gate inline to the cd4011 nand gate being its the only gear with 4 inputs grounded.
*****This legend stated above by evilstuie in thread is correct****** Wire Gear: Park Rev. Ntrl. O.D. Drive 2nd 1st Signal A GND GND Open Open GND GND Open Signal B Open GND GND GND GND Open Open Signal C Open Open Open GND GND GND GND Signal D GND Open GND Open GND Open GND
****PARTS USED*****
4 x 10k ohm resistors
7 x 2k ohm resistors
7 x 5mm led lamps
2 x cd4011 quad, dual input nand gates
1 x cd4002 dual, quad input nor gate
1 x 10uF electrolytic cap
4 x .1uF ceramic caps
The 4000 series logic chips used are static sensitive, so use caution when handling the chips outside of a circuit, and terminate all unused inputs to ground or +supply.
That could also be used to revive the Gen4 odometer project, of course you can never break even for the effort, but the community would welcome some sort of available project that they could implement without relying on specialized hardware.
@drewtronics
Great Job. I ended up getting distracted with a Raspberry Pi/Android/PC hybird AI for the car dash. Is thinking of using some of the inputs on the PI to create a virtual NAND gate to do it, but never got around to it.
A hardware solution like yours though would be a more solid option though and a lot cheaper to implement.
@drewtronics
Great Job. I ended up getting distracted with a Raspberry Pi/Android/PC hybird AI for the car dash. Is thinking of using some of the inputs on the PI to create a virtual NAND gate to do it, but never got around to it.
A hardware solution like yours though would be a more solid option though and a lot cheaper to implement.
Sounds like a cool setup! A few lines of code and some IO pins and you could do the same thing I did or better!
There must be a dozen ways a guy could implement this kind of an indicator.
I appreciate the leg work you did on the data output of the 4l60 connector. I could not find any other information on the web about an indicator like this, perhaps its out on the web some place, but I never found it.
When you get your unit built out, post back. I'd like to see it.
Will Do.
Just working out some of the kinks with the mapbox navigation but hoping to be running in-car in the next 2 months.
ChatGPT integration, voice clone, remote control of most of the cars functions (not quite up to self driving yet haha) and AI camera detection for license plates, car ID and object IDs are all tested and working as well.
The video you posted of it back in 23 is incredible, I am sure the final version will be killer. The graphic options available to you on a system like that is wild.
So much time and effort goes into these types of one off designs. Rather nice to see the final results, even better to get to use it on the street.
I know this thread is old, but this is the only thread I found on the internet talking about this type of indicator for the 4L60e.
I have some additional details I used to finish the build out, hope it helps someone looking to do the same.
I used 7 LEDs anode to a common +12 supply. The circuit sinks the cathode of each LED via CD4011 nand gates.
The 3 drive gear uses a cd4002 dual quad input nor gate inline to the cd4011 nand gate being its the only gear with 4 inputs grounded.
*****This legend stated above by evilstuie in thread is correct****** Wire Gear: Park Rev. Ntrl. O.D. Drive 2nd 1st Signal A GND GND Open Open GND GND Open Signal B Open GND GND GND GND Open Open Signal C Open Open Open GND GND GND GND Signal D GND Open GND Open GND Open GND
****PARTS USED*****
4 x 10k ohm resistors
7 x 2k ohm resistors
7 x 5mm led lamps
2 x cd4011 quad, dual input nand gates
1 x cd4002 dual, quad input nor gate
1 x 10uF electrolytic cap
4 x .1uF ceramic caps
The 4000 series logic chips used are static sensitive, so use caution when handling the chips outside of a circuit, and terminate all unused inputs to ground or +supply.
GOOD LUCK!
Instead of using 4000 series devices why not use the old school 7400 series TTL chips, no issues with static.
You could use the 7400 series logic, and do the same thing. I think you would need to lower the supply voltage to 5v. 7v max. Also adjust the resistor values to get the desired brightness.
I do not remember what the OPEN state voltage from the PCM is. If its 12v, you might have unintended complications. I just don't know.
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Custom Shift Indicator for 4L60E 
