I piggybacked a C3 series ecm onto a later PCM application that uses an E trans (4L80E). Is there any pin that I can tap into, to use as a P/N switch input for the older ecm?.
TIA

 

You could use the range switches to determine when its in P/N. A logic circuit of some sort would be needed from what I see. It appears that when the range switches one and three are open and range switch two is closed the vehicle is in park/neutral.

 

I need to know this too.

 

The range switches appear to be the only way.The combination of the three switches is what tells the PCM what gear has been manually selected. The other way would be to patch it to turn on an output when in P/N has been selected.

 

The later 4L60E's used an external switch setup.
If the 80's did too you might be able to swap the selector
shaft out and install the switch.

What about the starter interlock circuit?

 

Yeah, Range A B C... not looking easy. Everything I've found tells me nothing other than what they should read with ignition on and what they should read with engine running.
Grumpy, are there any wires coming off of the shifter?

 

"There are three sets of contacts on the transmission range switch, both on the column shifted cars and the floor shifted '96 Impala. They are or the reverse lights, starter lockout and P/N input to the PCM. The reverse lights obviously just turn on and off the backup lamps, the starter lockout simply prevents the car from being started if you're not in park or neutral and the P/N position input tells the PCM if you're in park/neutral or not (also allows the trunk release to operate)."
http://www.lt1edit.com/pipermail/lt1...20/019242.html

So I'd say one of those "range" pins is probably the normal p/n switch .

edit: Even if the above doesn't work for the truck you might look at the wiring that disables the starter relay. I'm sure if you tapped into that circuit it would provide a good p/n.

 

From the truck PCMs side, the combination of the three switches appears to be what tells it what position the manual shaft is at. Not the easiest thing to use if its your only option. This is all thats in the PCMs harness itself I think.

Obviously the other easy 'duh' option is to use the external switch on the actual shifter if one was present.

Me personally, though, id just say to screw it if your using a C3 in addition. Other then the extra few IAC counts added in and removed when shifting theres not much that youll miss from just having it think its in drive all the time.

 

I've just grown custom to having things, as *right* as possible.

Time to poke some, the steering column might be where I start.

Thanks all.

 

True... If its an easy fix then its a no-brainer.

As far as P/N and drive, the only real differences in my old 8063 was the addition/subtraction of IAC steps and only doing full closed loop idle when in drive, which was really annoying. I preferred drive all the time. Is this one romless with the U-TBI code?

With something like the PCM, though, then it actually can really matter. The routines in those are supprisingly sophisticated compared to the stock stone age stuff in the C3's (no offense...)

 

A what?.
Romless TBI?,
now that sounds interesting....

 

This is probably stupid to say, but I'll take the licks. I did a piggyback e-trans and 730 tpi ecm. Now the stupid part, I ran a manual trans .bin in the 730. It drove pretty normal. I'm sure it's not the best way to go, but it is possible.

 

While helping my brother with his G30 1ton bus i remembered seeing some stuff on the tranny, so i checked the ads file (A183)and it hate the chart in there for the inputs..

25 IODPORTC BIT STATUS
0 A/C REQUESTED 1 = ON 0 = OFF (1 = A/C REQUESTED)
1 BRAKE SWITCH 0 = ON 1 = OFF (1 = BRAKE PRESSED)
2 RANGE INPUT 1 1 = HI 0 = LOW
3 RANGE INPUT 2 1 = HI 0 = LOW
4 RANGE INPUT 3 1 = HI 0 = LOW
5 POWER STEERING PRESSURE SWITCH 1 = ON 0 = OFF (1 = CRAMP)
6 NOT USED
7 NOT USED

PRNDL TABLE:
------------
RANGE 1 RANGE 2 RANGE 3 GEAR
----------------------------------
0 1 1 LOW
1 1 1 DRIVE2
1 1 0 DRIVE3
1 0 0 DRIVE4
1 0 1 P/N
0 0 1 REVERSE


-mike