How I did my shift to park fix under a shade tree
No guarantee expressed or implied
It took me a couple days to round up the needed items
And about 30 min to fix, without dismantling my entire car.
1. I did change my shifter previously, the small pin that holds the leaver button was out of the socket…there is a you tube video about this…. I found a new shifter on line at a good price. I did repair the original one in case it is ever needed. The new shifter helped for a while.
2. the switch issue is complicated. Sometimes it is the switch itself not making a good connection, sometimes it is the metal tab that some folks bend to make the switch push all the way in to make a better connection, sometimes it is the leaver pin I mentioned in the shifter assembly, and sometimes it is bounce.
3. the inline device GM added is a 100 ohm resistor with a IN1004 diode. Albeit it looks like the diode is backwards, it is not. When the switch is engaged ( car in park ) the current draw is appox 2.9 mA at 12 volts ( well 13.6 or 14.2 depending on battery charge, engine running etc ) on this circuit. Basically you are pulling a pin on the computer chip to ground…about as simple and standard as it gets.
I can only speculate on the GM add on, it does not fix the switch issue per se .
However, when you slam the shifter, then wiggle it and cuss it and hit it and slam it you really don’t know how many times the switch made contact for a moment and then not, and the on board computer is now catching up … like your home computer when you out type it… i could be wrong ( but I’m not) and a de-bounce and slight current limiter ( with a snubbing diode) to the rescue. Because every time it bounces it slightly arcs ( 2.9 mA at 12 volt ) and you can study this in electronic theory or just take my word for it.
4 . Denali has no key. Push button to start . most of the Car is in Park info comes right off the transmission switch itself. This is why other than it dinging you to death it acts like the key is still on, but the car is safe. Well, I think to the computer the key is still on and in the ignition…except you have no key in the ignition. This is circuit 5905 .. the key capture column lock shift position signal. It’s the white violet wire a white wire with a violet stripe. on pin 11. you can count the pins don't confuse it with any violet wire with the white strip. they use both combos.
And… it shows up as pin 11 on the slate connector, easily accessible by pulling off the passenger side console cover… one 7mm bolt, a few snap locks and you are in.
If you are good with an exacto knife, and you can read wire color codes and pin numbers, the rest is pretty easy. Just trim a bit of the insulation off the white violet wire in the slate connector at pin 11. don’t chaff or cut anything else, and don’t cut the wire into or in two. Or in half either.
I took the actual GM part I found on line and used the diode and resistor. The short end of my alligator clip is the ground end. the black stripe on the diode is the positive end. I could have made this combo for 12 cents, but I didn’t know that at the time.
I used the ground stud shown, because good grounds are hard to find on plastic cars. I then taped a bit of tape over the clip at the wire for good luck.
Why I used the resistor and diode when in theory you could ground the wire direct you ask. In my humble opinion a slight amount of current limiting hurts nothing, since this circuit was really not intended to be brought to ground all the time, and at this connector we are closer to the main computer so we do not have the slight bit of wire resistance to the switch, and mainly because I bought the thing and wanted to use it. Plus sometimes my switch in the shifter probably still works as normal or even bounces and this minimizes the switch bounce issue.
Don’t get on the wrong wire. Don’t cut anything , you could even use one of those fancy crimp on wire splice things from the local auto parts store on the white violet wire ..they call them T Taps I believe. The white violet wire size is .35
Or you can use the paper clip method. but this worked well for me. happy honking.
