Since there is a separate thread on the C203 and C500 pinouts for later years I thought I would start one on the pin outs for '84.

I forget where I got this from but here is what I have for C500:

There are a couple errors for the given C500.

Two that I know:
B1 is not [Cruise Control/Fuel Injection]. B1 is actually a lead for the VSS (high I think but I'm not sure)
C1 is not [Cruise Control/Fuel Injection]. C1 is actually a lead for the VSS (low I think but again not sure)

I've seen this a couple times now on 84's with manuals. I believe those with an auto are the same but I can't say for sure.

[This message has been edited by GraterFang (edited 03-16-2012).]

84 C203

Pin
A= Upshift light
B= Fuel pump power to relay
C= Check Engine light
D= A/C enable relay control
E= Oil light
F= HIR +12v fuel pump/ECM
H= 1/2 VSS signal from speedo
K= A/C from relay
N= A/C power from fuse to relay
P= TCC +12v when brake not applied
R= +12v when cranking

84's have their power distribution basically coming off the start am I correct in saying that? Would it be a better idea for me to use a distribution block from later years and re-route E4 and A5 of the c500 to the block instead?

quote Originally posted by 84se2m4: 84's have their power distribution basically coming off the start am I correct in saying that? Would it be a better idea for me to use a distribution block from later years and re-route E4 and A5 of the c500 to the block instead?

Yes...that would be better. Ogre's Cave even suggests bypassing the C500 and connecting the Chassis side of that wiring directly to the distribution block.

I would like to add my own 203 and 500 charts. In general, these match what else has been said (other than pin M of the C203...nobody else mentioned it). These are all confirmed from a perfect 84 auto wiring harness...my charts might be missing some manual stuff. If it isn't listed here, then it isn't used on an 84 auto engine harness.

C203
A - unknown color - Upshift Light
B - Orange - Fuel Pump Fuse
C - Brown/white - SES light
D - Lt Blue - A/C Request (from HVAC controls)
E - Tan - Oil Gauge (or is it a light?)
F - Pink/black - Fused ECM
H - Brown - VSS 2000 PPM - speedo to ECM
K - Green - A/C control from relay
M - Black/white - Ground to Engine/ALDL
N - Brown - A/C Clutch Relay
P - Purple - TCC Brake Switch feed
R - Purple/white - Crank in to ECM


C500
A1 - Dk Green - A/C Control
A2 - Black - Battery Ground
A4 - Yellow (auto)/Purple (Manual) - Starter Solenoid (through gear selector switch)
A5 - Red/white - Power dist
B1 - Yellow - VSS High
B3 - Brown - Charge light
C1 - Purple - VSS Low
C2 - Tan - Coolant Temp Light
C3 - Black/white - Tach signal
D1 - Green/white - Coolant fan
D2 - Green/Black - Coolant fan
D3 - Green - Coolant temp gauge
E1 - Green - Backup lights
E2 - Blue - Backup Lights
E3 - Pink - EFI (coil)
E4 - Red - Power distribution

For good measure, here are the ECM pins
Red/White connector
2 - Brown - Vehicle Speed in
3 - White/black - Diagnostic Enable In
5 - Orange/black - Park Neutral Switch In
7 - Orange - Serial Data
8 - Blue - Inj. Control
10 - Orange - Power In
11 - Gray - 5v ref out
12 - Black/white - Ground
13 - Black/white - Ground
14 - Black/orange - Ground (MAP)
15 - Orange - Power In
16 - Pink/black - Power In
18 - Green/white - Fuel Pump Relay
19 - Tan/black - TCC Clutch (Auto only)
20 - Brown/white - Check Engine light
21 - Lt Blue - A/C on (12v+ when AC is on at HVAC controls)

Blue/Black connector
1 - Purple/white - Crank In
2 - Purple/white - Pulse In
3 - Black/Red - Ground
4 - Yellow - Temp in
5 - Dk Blue - TPS in
7 - Dk Blue - A/C relay ground (grounded in ECM when power shows on red/white pin 21)
8 - Purple - O2 sensor
10 - Tan/black - Ign Mod Bypass
11 - Black - Ground
12 - Green/white - Hi IAC B Coil
13 - Green/black - Lo IAC B Coil
15 - Tan - Ground
17 - Lt Blue/white - Hi IAC A Coil
18 - Lt Blue/black - Lo IAC A Coil
19 - White - Spark Timing Out
20 - Green - Input (MAP)


If anyone needs a full color verified engine wiring diagram for the 84, let me know. I have it in Visio format...but it is hard to read when I shrink it to a PDF (need to make some changes so I can get this out to people more easily).

GREAT! Thanks CPT! This will help alot.

speedo didnt work for the longest time, pin M is the speedo ground, when i discovered this it worked a treat. I think its called VSSB Ground

quote Originally posted by 84se2m4: speedo didnt work for the longest time, pin M is the speedo ground, when i discovered this it worked a treat. I think its called VSSB Ground

Ahhh...another one of those 84 eccentricities explained...thanx, I will add that to my notes.