What gear are YOU in?
 

So I'm going up a hill one day, and the car didn't have any power. It felt like I was in 3rd, but it shoulda been in 2nd. Every once in a while, I wonder if the car's in 3 or 4 (D or oD).

I had an idea, so I pulled out the manual, cause I needed to find out how the PCM tells the tranny what gear to be in. It's as simple as two wires, providing the ground for two solenoids. Digitally, two wires can represent up to 4 combinations, in the tranny's case: PRN1, 2, 3, and 4.

Decoding such a signal is easy, so I set out to modify the gear indicator (to the left of the shift) to show which gear was selected (as normal, PRND1234) and to display which gear the car was in (1234). Designing such a device is easy, but building, implementation, and modifing took a little longer.


http://www.public.iastate.edu/~glang...l/sft_day1.jpg http://www.public.iastate.edu/~glang...l/sft_ngt1.jpg
ABOVE: 4 blue LED's have been added (1, 2, D, and oD) to show which gear the PCM is requesting (coincidentally, what gear the car is usually in). The blue light showed up pretty well, as did the refelctions of the other 3 LED's above it (left image), which cannot be seen otherwise, even during the day. The red selector light is hard to see, but it is still there (at the momment in Park). When the two lights converge, purple is seen.

To allow for color, the red tint was removed from the lenses of the gear indicator bubbles. Lukily, I had already replaced the bulb that lights these with a red LED months ago, therefore missing the red tint didn't matter.



http://www.public.iastate.edu/~glang...el/sft_mod.jpg
ABOVE: This is the device doing the decoding. It recieves 5V, common/gnd, illumination que, and the 2 solenoid (A & B) inputs, borrowed from the PCM with a snap-on spitter. It outputs 4 signals for the LED's and a common/gnd shared by all 4. It follows the schematic below pretty well, although I modified it later to follow the schematic exactly, and to accommodate external plugs for transitions/removal. Power, common, and illumination/dimmer input are borrowed from the harness located to the left of the shifter, which supplies the backlight and power to the gear indicator.



http://www.public.iastate.edu/~glang...el/sft_exp.jpg
ABOVE: Location of modules (including a separate module for controlling a 5v source). At present, they sit in there pretty nicely, and aren't mounted.


Below is a how-to if you're handy with electronics. There is a lot left unsaid, but I figure if you can read the diagrams and understand them, there's no reason to waste text explaining the obvious.

As with any electronic project, asses the design and test it before you implement it.

http://www.public.iastate.edu/~glang...el/sch_pwr.gif



http://www.public.iastate.edu/~glang...el/sch_dec.gif



http://www.public.iastate.edu/~glang...el/sch_dim.gif

That is a really cool idea. Sign me up!!

I'm not sure I understand what that really does. Mind you my car is old, and kinda dumb. Does this effect performance or anything?


-justin

o0o0o, I like that.Might be useful, I went ahead and bookmarked it incase I need it...

you mean there is actually supposed to be a light in there to tell u what gear ur in? i guess mine was out when i bought the car cuz i always thought i was just guessing without the indash indicator that i kno is on the se

Won't work for you. Your transmission isn't electronically controlled.

NERV: Yeah, when you move the shifter, it mechanically (via fiber optics) lights the corresponding light. Example: When you're in park, the red park dot will light. When I got the car my bulb was burned out, so I replaced it with an LED, and wired it so that it dims with the rest of the gauges at night.

opensourceguy: This isn't a mod or anything, it's just something neat I wanted to play with. Keep in mind it shows you what gear your transmission is in, which may be different that the gear RANGE you have selected with the shifter.

ALSO: This was performed on a 95. It may not work at all (older vehicles) or as described (newer cars) for your year.

Oh.. mine is mechanical.. guess this isn't for me. Oh well, seemed cool at first. Oh yeah and my tranny isn't electronically controlled, so true 8)


-justin

how do i replace this light? its not listed in the manual or the haynes manual

You lost me after "You were going up a hill one day." Sorry. :?