The Series II 3800 swap has become very popular in Fiero circles. Once the work is done,
it's hard to get out of the car and document things for those who follow. Dan has kindly
taken some tips and photos along the way. Hopefully his material is a help to someone.
His background is in avionics, and he has tried to simplify the mystery of wiring the car.
The tables for PCM pinouts have the wires listed along with the appropriate changes for his swap.
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Dan has swapped the 4T65E HD tranny along with the engine. He has used a 1998 Pontiac Grand Prix GTP PCM.
All wiring and other directions relate to this combination.
General Overview
Dan: The swap consists of the 3800 motor/tranny/PCM/harness being mated to the existing Fiero
structure. Some modification and strengthening of the cradle was done, as well as designing and
building an exhaust system for the car.
Click for Cradle info
Wiring
The wiring is the biggest part for this swap and also the most time consuming.
I chose to mount the PCM in the remains of the trunk to allow more room for other things.
With the PCM in the trunk, it is a lot easier to run wires and there is more room in the cabin
for other things.
Basically other than battery power and ignition power, as well as grounds for the various sensors
and modules, most of the harness is left intact. The wiring to such things as the fuel pump
system, with its relay and pump control module had to be added. Some other emissions systems
like the rear O2 sensor had to be dealt with. I have kept the passkey system mounted near the PCM.
With the original key, this system provides added security. The fiero wiring harness through the firewall
is used as much as possible. The 3800 s/c needs more ignition sources. One is available because the 2.8 has an
extra injector wire. Also unused Fiero wires were run from the fuse box ignition connection to provide some more
fused power sources.
PCM
Here are tables showing the connectors to the PCM. Changes are bold for easy reference.
Blue PCM Connector
Clear PCM Connector
Fiero Harness Connectors
The wiring may vary by year or model but this is a guide.
Fiero C203 Connector Info
Fiero C500 Connector Info
VSS
I used the VSS signal converter found on the Fiero addiction web site. any thanks to Jon as this site is extremely
useful for swappers.
Exhaust
The exhaust system I used is basically a spiral of pipe, cat, muffler, tail pipe. This meant that the bottom part of the
trunk was removed for space. Thanks again to Fiero addiction for many pics of alternate systems.
Contact Me
Updated 8 July 2003