Not sure where to post this question but here it is
I bought a 91 Z-28 originally a TPI car but the previous owner hacked it out and was running a carburetor. Recently there was a fire and melted the majority of the engine harness. My question is can I replace the original harness with one from TBI car as they are a lot cheaper than the TPI harness. I will obviously only be using the power for the distributor,alternator and starter. Any other advice would be appreciated.

 

Are you asking because your going carb or tbi ?
with the carb swap all you need is alt wiring and distributor power and lighting through c100 if automatic tci makes a kit for tcc lockup.
Tbi , tpi and 3.1 all go through the fender well and arnt needed to run a carb.

 

Car was already swapped to carb. I’m just going to keep it that way. The tbi harness is a lot cheaper than the tpi. The original harness is completely burnt as well as all connectors and would probably be easier to just run a new one.

 

As mentioned why would you need the efi harness if your carb ?

 

Starter,alternator,factory tach,harness for trans,fuel pump relay

 

Everything but the fp relay and tcc is going through c100

 

C100 for the 90-92 =



Looks like the only difference from TPI to TBI is that TBI has wiring for the Speedo. (TBI speedo uses a VSS Buffer,.... but TPI speedo is handled by the ECM.)

Firebird 90-92 harness might be a little different (fog lights?) but should still be useable with a little work.


Here is the C207 info:

1990 - 1992 C207

PIN Color From / To (Notes)
A Brown ( TBI )
B* Pnk (Red) INJ1 TBI (TBI)
B* Pnk/Blk INJ1 (V6 / TPI)
C Brn/Wht ECM / CE Light
D Grey Speed ECM to Cluster (Not with TBI)
E Wht/Blk ALDL (pin B) / ECM (test)
F Pnk/Blk ECM fuse / ECM
G* Pink/Blk (white) INJ2 TBI (TBI)
G* Pnk/Blk (INJ2 V6 TPI)
H* Tan/Blk ALDL / TCC-ECM (auto)
H* Tan/Blk ALDL / Upshift (stick)
J Org ALDL (pin E) / ECM
K Brown ECM / Buffer (Only TBI)
L Drk Blue Vats to ECM
M Org Interior Lights
N Org/Blk ECM / P/N switch
P Red Speed Sensor (Not with TBI)
R Ppl/Wht Crank Fuse / Cold Start-(only TBI)

 

So no ecm means no speedo if I’m understanding this right

 

If the ECM is removed from a TPI ( or MPFI ) car,... there will be no speedo. The 2 speedo sensor wires lead directly from the tranny to the ECM.



If the TPI ECM is removed you can re-create the TBI speedo wiring in place of the ECM so that the Speedo works properly. You'll need a VSS Buffer, it's plug/pigtail and some spare wire.

On TBI cars the 2 speedo wires lead to C100 ( drivers side of the firewall ). If you connect a TBI ENGINE harness to your (originally) TPI dash harness car you will need to splice into those 2 speedo wires and connect them to a VSS Buffer assembly. Then connect 'switched' power and ground to the VSS Buffer. Finally, You'll need to connect the dash cluster to the VSS buffer; a good place to make this connection is @ the C207 connector PIN 'D' ( GRAY wire ). If you also wish to retain cruise control there is 1 more wire splice to make; you can do this at C207 of the TPI dash harness too ( PIN 'P', RED wire)

 

Just buy a Dakota digital sgi-100bt to use as a adjustable buffer