My first love was (and forever will be) electronics. I
love to play around with circuits. Even if my circuit
doesn't work, I can normally get it to do so. Normally
I start with small, primative circuits then keep
improving them until it works the way I want it to. It
is this hobby which is the reason why I'm building a
10-tube, 4-channel, 3,000+ watt amp for my Dynasty (I
don't even play my music that loud, not that Pink
Floyd was ment for that kind of loudness, lol), also
the reason why I'm also building a data logging system
for my car, the Megasquirt, and, it was even why I
picked the 3.3 Dynasty to play around with (what
better for this wierd hobby of mine then to pick
Chrysler's first DIS engine, first computer assist
tranny, and electronic options-filled Imperial-like
car?).
Well well well.
I've been putting some major thought into how one can
go from analog to digital dash on the AC/AY bodies. I
can't remeber if Brad mentioned once that he'd like
his Imperial to have the digital dash... or if that
was someone else. Regaurdless, I've heard many people
say they would have liked that 90's Imperial more if
it was more like an Imperial (more options!). Wanting
digital dash for myself......
Some 90's Imperials got analog (Brad's?) while some
got digital. Same goes for a few other AC/AY's. No
Dynasty got digital dash, though the analog Dynasty
used the same cluster as the analog Imperial...
So I got thinking- there HAD to be a way to go from
analog to digital dash.
Knowing Chrysler's EEK idealogies, I figured it would
be a simple difference in connectors/harnesses, or
MAYBE even wire colors. So I set out to see how I
could go from analog to digital....
I heard from some other AC/AY guys that '92 and '93
clusters are interchangable- but a '93 won't work on a
'91 and vise versa....
So I went out and bought a used '93 digital cluster.
My first thought was "will this fit?", as the Imperial
had a slightly different dash then my Dynasty. Well,
let's just say it's close even that if it does not
fit, I will be able to justify cutting 1 or maybe 2mm
of plastic off of my dash to allow it to fit:)
Then I went and started cleaning the cluster, turned
it over, and went oh s__t. The digital cluster has a
13 pin connector harness. The analog has two connector
harnesses (left and right) with something like 10
wires ea connector. Well, then that means there is a
pretty big electrical difference between the two
clusters.
So I sat down with my '90 FSM- and that was almost 3
days ago. After having studied the diagrams plenty,
re-drawn much of the connectors, color charts, I think
I've figured it out.
Aparently, Chrysler had a couple different AC/AY body
computers. Basically this body computer controled your
options, like if you have memory seats, this computer
will "remeber" the configuration of the seats, etc.
Different option packages got different body computers
(i.e. bare bones no-frills, no options AC/AY as
opposed to a fully loaded Imperial....).
This computer has several inputs (from sensors, TCM,
PCM, etc., etc.). These inputs are then used to figure
out what data to "output". On analog AC/AY's, it
appears that sensor data either goes strieght to the
PCM and body computer or to the PCM and then from the
PCM to the body computer. When the body computer sees
a sensor input which means something bad is going on
(i.e. no oil pressure), it will send a +DC volt signal
to the analog cluster to light up an idiot light. Each
idiot light has it's own wire and gets it's voltage
from the body computer. The analog cluster get's it's
gauge inputs (i.e. volt meter, speedo, etc) directly
from the proper sensors.
With the digital dash cluster, things get complex.
With that system, you basically have a digital LED
display center, an overhead digital console, and the
body computer.
Sensor data goes to both the body computer and EVIC
(overhead console). The idiot lights work just like
with analog.
The gauges are a whole different story.
Both the analog and digital systems have body
computers which put out a "CCD Buss positive" and "CCD
Buss Negative". This is a computerized signal,
compariative to any computer data transfere system,
like USB or serial. On all AC/AY's, this data goes to
the blue diagnositic port under the dash.
These two wires carry all kinds of coded information.
With the digital dash AC/AY, this code goes from the
body computer to both the EVIC, diagnostic port, and
the cluster.
The EVIC's internal electronics de-code these
electronic signals and uses them to display different
things on the EVIC display.
The digital cluster decodes this information and uses
it to display all the information in the LED gauges.
So technically speaking, the electronic cluster has
only LED's which display what the body computer tells
them to display- like an alarm clock.
And so a digital dash conversion is possible- here's
how.
First, get the EVIC and cluster, and new harnesses
from the dealer (the connectors which plug into the
EVIC and cluster- EVIC has one two-part connector and
the cluster has one connector).
Then, you remove your dash. Unplug the analog cluster.
To get the idiot lights on the digital dash to work,
you spice wires into the old analog harness and wire
the spices into the new harness you bought.
Then you need to get the CCD Buss wires and a few
things not found on the analog harness wired up. You
could tap into the CCD Buss's in the diagnostic
harness. Then you need to get a fused +12volts from
the battery (just get it from fuse #16 in the fuse
box). This should be all that's involved with getting
the digital dash to work.
The EVIC ties into the CCD Buss, and some sensors and
such.
And that should be it. Now this info is all from my
1990 FSM- other years (including my '92) MAY be
different.
I have also not YET tested this, so this is all just
my theory and may not be the case. One possibility I
see is that perhaps different body computers put out
different CCD Buss's. If this is the case, digital
dash and EVIC would not work until you replace the
body computer with one from a car which had EVIC and
was also from the same model year as your car.
When I update my site again, I will be including all
this information, 1990 wire colors for this, and more
detaled info. I plan to also have this info in the
1990's section of the Imperial club site when I know
from my car rather this all works or not!
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