I have a 1985 firebird (originally 5.0 with 700r4). I have swapped the quadrajet for a holley and the esc dizzy for a vacuum advance dizzy. I have removed a LOT of the unnecessary electronics. My question, is what signals are used by the ECM to shift the transmission? I want to remove as much as possible without interfering with the shift points and the lock up torque converter. Could anyone tell me if the ECM uses the vacuum sensor (MAP), baro sensor, vehicle speed sensor (behind the cluster), etc...

I do plan to keep the ECM for the coolant temp, oil pressure, and other various things. Mostly so I can see that stuff myself. None of the engine is computer controlled at this point.

Any help is appreciated!!

 

None: The only way the tranny is "controlled" is by the TV cable ( mechanical ) and the TCC lock-up ( electric. ) Transmission shift points are controlled by (fluid) line pressure and the TV cable adjustment - not an electric signal.

If you have removed the ECM than you have already lost your TCC lock-up function. It's a good idea to buy a ( factory or aftermarket ) kit to get your TCC lock-up working again.


The ECM doesn't control these things. There is a CTS for the ECM,.. but it's used to control spark/fuel and since you are using aftermarket ( non CC ) Distrib and carb,.... there's no need for a ECM CTS.

 

Thank you VERY much for your input. Good information here. According to wiring schematics, it appears that the coolant temp and oil pressure wiring goes through the pcm and then to the cluster. Is there another way those are wired up, or am I reading them incorrectly? That wiring has not (yet) been molested.

Again, Thank you for your help John!

 

I don't have the 85 Firebird schematics to look over,..... but MOST ( if not all ) carb cars had the coolant temp and oil pressure wires running thru the C100 firewall connector.

Here is a schematic of the 85 CAMARO C100 Drivers side firewall connector ( you can check your 85 Firebird C100 plug to see if the coolant and OP wires are in the same spot )

Oil Press = 'E5' TAN wire
Coolant = 'F7' GREEN wire





Glad I could help,..... .Good luck !!

 

Here's an 85 T/A schematic in case some comes searching like I did. ;-)