Installed the Delco yesterday, seems to start faster, won't know about performance until computer adjusts.

I noticed the 94 module plug (right) has an extra black wire(I bent it up so you could see it) and different color codes while the 90 plug (left) has this wire omitted. It would be the fifth wire from left. But it starts up and runs.

Well a quick check of the wiring diagrams of these two years shows that the '90 module actually has 12 connections that do anything, while the '94 has 13 plus a ground. That ground may be your last connection, but i doubt it because you said it runs fine. Here'* the pinouts for the '90 and the '94 (90'* by pin letter and '94 is by color of wire, as far as i can decode):

1990:
A: WHITE to C8 on PCM
B: TAN/BLACK to C7 on PCM
C: Lt.BLUE/BLACK to D11 on PCM
D: PURPLE/WHITE to D8 on PCM
F: BLACK to C5 on PCM
G: BLUE/WHITE to CRANK SENSOR
H: Lt. BLUE/WHITE to " "
J: BROWN/WHITE to CAM SENSOR
L: BLACK/RED to D9 on PCM
M: GREY/RED to both CAM and CRANK SENSORS
N: WHITE/BLACK to " "
P: PINK/BLACK to FUSE #17, FUEL PUMP RELAY, OIL PRESSURE SWITCH

1994 (they only had colors, sorry)
WHITE- To gauges
RED/BLACK- B7 on PCM
BLACK- B9 on PCM
another WHITE?- B16 on PCM
TAN/BLACK- B15 on PCM
PURPLE/WHITE- B8 on PCM
Lt.BLUE/BLACK- B6 on PCM
PINK- Fuse 6 20A
BROWN/WHITE- In from CAM SENSOR
RED/BLACK- In from both CAM and CRANK sensors
WHITE/BLACK- In from both CAM and CRANK sensors
YELLOW- In from CRANK sensor
Lt.BLUE/WHITE- In from CRANK SENSOR

There you go hopefully this just makes sense to someone.

Maybe its a 93 I got the delco off of. It had the lower small plastic intake.
The extra wire on the delco is black with a white stripe.
Its in the K position.
My L is black /red on 90 and red/black on Delco.
the M is grey/red on 90 and red/black on Delco.
Thes two are 3rd and fourth from left.
So to simplify there are only 3 wires that are different color G,L,M.
K is ommitted on my 90.
G blue/white (crank) matches the yellow (crank) on the Delco.
so its just a matter of figuring out L,M (red/black stripe) on the Delco.
Let me think on this..........

Well that must have been something on the 93-94 that the 90 didn't use. I'd say as long as it runs OK you won't have to worry about it. I have a feeling that the black is for the RPM reading to the PCM, because the '94 has a separate wire specifically for gauges. On the 90 there is no gauge output just PCM outputs.

L & M still thinking.......
M grey/red (90) matches black red(93,94) in from cam & crank sensors.
so we are down to "L".
90 "L" is black /red stripe to D9 on PCM Delco is red /black stripe to B7 on PCM.
Thats the wild card! D9 (90) vs B7 (93,94) PCM wires?
Thats what I'd like to figure out. If its a ground we are golden.
Hey Alec thanks for the diagrams of wires.

I remember reading somewhere that extra wire was for a seperate tachometer signal that isn't needed on our cars. Don't hold me to it though.

Yeah, el capetan is correct. No worries about the extra wire.


-justin

My Haynes manual shows terminal M to be Ign/ fuse so I guess its power.
So they are the same just slightly different color codes in 3 places.