1G OHM harness install in a 1990 GST

[9 T GSX]

Need a little clarification in getting this modification completed, the harness has a connector for a AEM infinity instead of the stock ecu connectors.
As some know the 90's are a bit different than the 91+ when it comes to finding the correct connectors for this install. Such as 1990 car uses an 8-pin, 7-wire connector (C-67) and later manual transmission 1G cars have a 14-pin connector, instead of a 14 and 18 pin setup on the 91+ cars. I have been trying to figure this out looking at diagrams but I don't a 1990 specific electrical manual only a 91+. I think I'm on the right path,if you could take a look at the list below to confirm this would be great, as you can see I found a good amount of the wires on the C-67 connector but there are no other white connectors in this area just radio,ecu,MPI connectors.

Resources that has helped so far:

• Dash Harness
• OHM harness
• Control harness

First question: What/where is the other connector I need to find to install the other wires I have left?

The below is the pin-out for Connector C-67 for various 1990 models.

1 -M/T - NONE
(A/T ONLY - YW, yellow with white, Power/Economy Change Over Switch pin 1 to TCU pin 9)
2 -M/T - RB, red with black, magnetic clutch relay pin 2 to ECU pin 65/ #4 on OHM Harness
3 -M/T - RB, red with black, fuse 19 to ECU pin 103 for battery back-up/ #5 on OHM Harness
4 -M/T - 2.0L Turbo ONLY - BR, black with red, Boost Gauge (gauge cluster pin 6) to ECU pin 3/ #9 on OHM Harness
5 -M/T - LR, blue with red, fuse 3 to Power Window Relay pin 4 / #10 on OHM Harness
(A/T - RB, red with black, Magnetic Clutch Relay pin 2 to ECU pin 65)
6 -M/T - Y, yellow, Self Diagnosis Check Connector pin 1 to ECU pin 1/ #11 on OHM Harness
7 - M/T ONLY - W, white, Self Diagnosis Check Connector pin 10 to ECU pin 2/ #12 on OHM Harness
8 -M/T - RG, red with green, check engine light to ECU pin 64/ #13 on OHM Harness

This is the OHM instructions:
There should be 2 white connectors on your old 91+ 1G harness, one is a 14 way the other is a 18 pin, those need to be deppined and transferred to the new harness, no need to strip or cut any wires, just swap the connector following the numbers on them going from left to right on the new harness.
1. Empty
2. Brown ECU 19 TPS: Needs a Home
3. Empty
4. Black/White ECU 65 A/C Clutch Relay (can be used for other input when A/C not used) Found
5. Blue/Red ECU 103# Battery backup constant 12v (90 Used) Found
6. Empty
7. Black ECU 101 Ground to chassis: Needs a Home
8. Red ECU 101 ABS output (can be used as other input when no ABS used): Needs a Home
9. Yellow/Black ECU #3 Turbo boost gauge output Found
10. Blue (power window Relay) (90 Used) Found
11. Yellow ECU 1 Self diagnostic output (90 Used) Found
12. White ECU 2 Data transfer (90 used) Found
13. Green/ Red ECU 64 check engine light output (90 Used) Found
14. Green ECU 14 idle switch; Needs a Home

1. White (wiper): Needs a Home
2. Blue (wiper): Needs a Home
3. Empty
4. Empty
5. Tach signal power transistor: Needs a Home
6. Empty
7. Empty
8. Empty
9. Empty
10. Red (wiper): Needs a Home
11. Blue/white (wiper): Needs a Home
12. Empty
13. Yellow (reverse switch connector): Needs a Home
14. Orange (reverse switch connector): Needs a Home
15. Orange (coolant gauge): Needs a Home
16. Empty
17. Empty
18. Empty

That's all for now trying to keep the post nice and simple, Planning to do a how to with video as I go thru this so to help others in the future

 

[19Eclipse90]

Most likely they are referring to C-58 in addition to C-67. Those are the two engine control harness connectors that changed from 1990 to 1991+ and connect to another harness.

 

[9 T GSX]

I have made some progress and learning a lot, but this is turning into quite the project, Now I understand why OHM only makes the harnesses for the 91+ as the early 90's have a good bit of differences. Seems like the fitting 10lbs of #hit in a 2lb bag quote, Im sure it can be figured out as someone has had to do this before me.

Updated pins found mostly on pin C-58 or C-50 (for the 1990)

1. White (wiper): (C-50 pin 1 BW Blue w White) #1 White (wiper) OHM
2.Blue (wiper): (C-50 pin 2 LB Blue w Black) #1 White (wiper) OHM
3.Empty
4.Empty
5.Tach signal power transistor: 10 pin ECU Connect / Pin# 109 on ECU Connector White wire
6.Empty
7.Empty
8.Empty
9.Empty
10.Red (wiper): (C-50 pin #9 LB Blue w Red) #10 OHM
11.Blue/white (wiper): (C-50 pin# 10 LB Blue w Black) #11 OHM
12. Empty
13.Yellow (Back up light/reverse switch connector): (C-50 pin# 12 RL Red w Blue)
14.Orange (Back up light/reverse switch connector): (C-50 pin#13 R Red Wire)
15. Orange (coolant gauge): ( C-50 pin#14 YG Yellow w Green)
16.Empty
17.Empty
18.Empty

I have a 90 specific factory manual and have spent a good amount of time trying to find where these wires are and have come to a conclusion either they not in there or my schematic reading isn't up to par (likely the case). Here's the last of wires I need to try and incorporate into the harness.

1. All pins for C-58 (90) are utilized with OHM wires except Pin#1 which is empty on both connectors.

Issues: (I am using C-67 as my guide to find what C-58 should have in it). Not sure if that is correct though but is all I have to go by.
The following wires should be in C-67 but have no more pins left in C-58 and these are the wires I cant find a spot for:
(C-67 Pin # 2)ECU pin #19= TPS,
(C-67 Pin # 7) ECU pin# 101 Ground to Chassis,
(C-67 pin#8) ECU pin#101 ABS output “can be used as other input when no ABS used”,
(C-67 pin#14) ECU pin# 14 Idle switch.

This one is on C-50 (90) C-58 (91+): Pin#5 on C-58: Tach signal power transistor: 10 pin ECU Connect / Pin# 109 on ECU Connector White wire


Example: Lets look at (C-67 Pin # 2) ECU pin #19 TPS) current information is- Pin#2-GW, Green w/ White stripe – runs from pin 5 of the Auto-Cruise Control Unit to pin 2 on the Throttle Position Sensor, this is correct. Attached pictures is the 90 and 91+ schematics. As mentioned I have looked all thru the manual and I couldn't find this in the 90 manual. (C-58 Pin#2 in the 90) is taken with a RB, Red with Black, magnetic clutch relay pin 2 to ECU pin 65/ will be #4 on OHM Harness. Just doesn't seem like things are adding up huh?

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[19Eclipse90]

The 1990 manual shows:

C-50
[01][02][03][04][xX][Xx][05][06][07]
[08][09][10][11][12][13][14][15][16]

[01] - Blue w/ white, pin 4 of Wiper Motor (front) to pin 7 of Steering Column Switch
[02] - Blue (FSM shows the male side to be LG, blue w/ green stripe) – pin 3 of Wiper Motor (front) to pin 8 on inside junction block Connector C-46, ultimately to fuse #9, "Wiper"
[03] - Black w/ white, pin 3 of Magnetic Clutch Relay to pin 1 of Magnetic Clutch
[04] - Green w/ yellow, pin 1 of A/C dual pressure switch to both pin 4 of A/C magnetic clutch relay and pin 1 of engine coolant temperature switch for A/C.
[05] - White, pin 1 of Noise Filter to pin 12 of Combination Meter (Gauge Cluster)
[06] - Blue w/ yellow, pin 9 of Auto-Cruise Control Unit to pin 3 of Auto Cruise Control Actuator
[07] - Blue w/ black, pin 20 of Auto-Cruise Control Unit to pin 4 of Auto Cruise Control Actuator
[08] - Yellow w/ Green, pin 1 of Brake Fluid Level Sensor to pin 36 of Combination Meter (Gauge Cluster)
[09] - Blue w/ red, pin 1 of Wiper Motor to pin 3 of Steering Column Switch
[10] - Blue w/ black, pin 2 of Wiper Motor to pin 4 of Steering Column Switch
[11] - Green w/ white, pin 1 of A/C control unit to pin 2 of A/C dual pressure switch
[12] - Red w/ blue, pin 2 of Back-Up Light Switch to pin 2 of each Back-Up Light (Right and Left Sides)
[13] - Red, pin 1 of Back-Up Light Switch to output of fuse #18 ("BACK" fuse, pin 2) at junction box in driver side foot panel
[14] - Yellow w/ Green, pin 1 of Engine Coolant Temperature Gauge Unit to pin 10 of Combination Meter (Gauge Cluster)
[15] - Blue w/ orange, pin 7 of Auto-Cruise Control Unit to pin 1 of Auto Cruise Control Actuator
[16] - Blue w/ red, pin 2 of Auto Cruise Control Actuator to of C-10 Diode, past that to pin 1 of Stop Light Switch


C-58 (MANUAL + TURBO)
[01][xX][Xx][02][03]
[04][05][06][07][08]

[01] - none
[02] - Red w/black, pin 2 of A/C Magnetic Clutch Relay to pin 65 of MPI Control Unit
[03] - Red w/ black, output of fuse #19 ("ROOM" fuse, pin 2) at junction box in driver side foot panel to ECU pin 103 for battery back up
[04] - Black w/ red, ECU pin 3 to Combination Meter Pin 6 for Boost Pressure Gauge
[05] - Blue w/ red, output of fuse #10 ("HEAD" fuse, pin 2) at junction box in driver side foot panel to pin 4 of Power Window Relay
[06] - Yellow, ECU pin 1 to pin 1 of Self-Diagnosis Check Connector
[07] - White, ECU pin 2 to pin 10 of Self-Diagnosis Check Connector
[08] - Red w/ green, ECU pin 64 to Combination Meter Pin 8 for Check Engine Light

Just a few notes I want to make when reading over your post:

• No ABS in a 1990 so anything related to that can be ignored.
• The Auto-Cruise Control Unit and Actuator was different from 1990 to 1991. That may be why the 1990 does not show a link to the idle position switch.
• More of a mental note for myself and perhaps others that are following along, for purposes of this thread:
  
  _________________________C-50 on 1990 harness is C-58 on 1991+
  _________________________C-58 on 1990 harness is C-67 on 1991+
  ​
• In general, you've posted a lot of information that is very difficult to sort through and follow. It is honestly a bit overwhelming trying to locate the questions within your posts. It looks like you've got C-58 (1990) figured out.
• When I swapped a 1991 harness into a '90, I moved the connectors from the '91 body harness over to the '90 vehicle so that I did not have to mess with the 1991 engine harness. The extra wires on the 1991 harness had a home but did not ultimately mate with anything on the '90 vehicle.
• I extended the wires from the 1991+ Auto-Cruise Control vacuum pump location (1991 harness) to the location of the 1990 Auto-Cruise Control Actuator. Using the 1990 Actutator and Cruise Control Unit, the cruise works without any additional wiring which suggests to me that the C-67 (1991+) pin 2 and pin 14 are not necessary if you're retaining the 1990 cruise system or eliminating it all together.
• You show C-67 (1991+) pin 7 going from ECU pin 101 to chassis ground - I see pin 7 going from 1991+ Auto Cruise Control Unit pin 14 to chassis ground. ECU pin 101 is on C-64 and goes to ground.

If you have further questions, I'd recommend being as specific as possible and I'm sure we'll be able to help guide you through it all.

 

[9 T GSX]

The 1990 manual shows:

C-50
[01][02][03][04][xX][Xx][05][06][07]
[08][09][10][11][12][13][14][15][16]

[01] - Blue w/ white, pin 4 of Wiper Motor (front) to pin 7 of Steering Column Switch
[02] - Blue (FSM shows the male side to be LG, blue w/ green stripe) – pin 3 of Wiper Motor (front) to pin 8 on inside junction block Connector C-46, ultimately to fuse #9, "Wiper"
[03] - Black w/ white, pin 3 of Magnetic Clutch Relay to pin 1 of Magnetic Clutch
[04] - Green w/ yellow, pin 1 of A/C dual pressure switch to both pin 4 of A/C magnetic clutch relay and pin 1 of engine coolant temperature switch for A/C.
[05] - White, pin 1 of Noise Filter to pin 12 of Combination Meter (Gauge Cluster)
[06] - Blue w/ yellow, pin 9 of Auto-Cruise Control Unit to pin 3 of Auto Cruise Control Actuator
[07] - Blue w/ black, pin 20 of Auto-Cruise Control Unit to pin 4 of Auto Cruise Control Actuator
[08] - Yellow w/ Green, pin 1 of Brake Fluid Level Sensor to pin 36 of Combination Meter (Gauge Cluster)
[09] - Blue w/ red, pin 1 of Wiper Motor to pin 3 of Steering Column Switch
[10] - Blue w/ black, pin 2 of Wiper Motor to pin 4 of Steering Column Switch
[11] - Green w/ white, pin 1 of A/C control unit to pin 2 of A/C dual pressure switch
[12] - Red w/ blue, pin 2 of Back-Up Light Switch to pin 2 of each Back-Up Light (Right and Left Sides)
[13] - Red, pin 1 of Back-Up Light Switch to output of fuse #18 ("BACK" fuse, pin 2) at junction box in driver side foot panel
[14] - Yellow w/ Green, pin 1 of Engine Coolant Temperature Gauge Unit to pin 10 of Combination Meter (Gauge Cluster)
[15] - Blue w/ orange, pin 7 of Auto-Cruise Control Unit to pin 1 of Auto Cruise Control Actuator
[16] - Blue w/ red, pin 2 of Auto Cruise Control Actuator to of C-10 Diode, past that to pin 1 of Stop Light Switch


C-58 (MANUAL + TURBO)
[01][xX][Xx][02][03]
[04][05][06][07][08]

[01] - none
[02] - Red w/black, pin 2 of A/C Magnetic Clutch Relay to pin 65 of MPI Control Unit
[03] - Red w/ black, output of fuse #19 ("ROOM" fuse, pin 2) at junction box in driver side foot panel to ECU pin 103 for battery back up
[04] - Brown w/ red, ECU pin 3 to Combination Meter Pin 6 for Boost Pressure Gauge
[05] - Blue w/ red, output of fuse #10 ("HEAD" fuse, pin 2) at junction box in driver side foot panel to pin 4 of Power Window Relay
[06] - Yellow, ECU pin 1 to pin 1 of Self-Diagnosis Check Connector
[07] - White, ECU pin 2 to pin 10 of Self-Diagnosis Check Connector
[08] - Red w/ green, ECU pin 64 to Combination Meter Pin 8 for Check Engine Light

Just a few notes I want to make when reading over your post:

• No ABS in a 1990 so anything related to that can be ignored.
• The Auto-Cruise Control Unit and Actuator was different from 1990 to 1991. That may be why the 1990 does not show a link to the idle position switch.
• More of a mental note for myself and perhaps others that are following along, for purposes of this thread:
  
  C-50 on 1990 harness is C-58 on 1991+
  C-58 on 1990 harness is C-67 on 1991+​
• In general, you've posted a lot of information that is very difficult to sort through and follow. It is honestly a bit overwhelming trying to locate the questions within your posts. It looks like you've got C-58 (1990) figured out.
• When I swapped a 1991 harness into a '90, I moved the connectors from the '91 body harness over to the '90 vehicle so that I did not have to mess with the 1991 engine harness. The extra wires on the 1991 harness had a home but did not ultimately mate with anything on the '90 vehicle.
• I extended the wires from the 1991+ Auto-Cruise Control vacuum pump location (1991 harness) to the location of the 1990 Auto-Cruise Control Actuator. Using the 1990 Actutator and Cruise Control Unit, the cruise works without any additional wiring which suggests to me that the C-67 (1991+) pin 2 and pin 14 are not necessary if you're retaining the 1990 cruise system or eliminating it all together.
• You show C-67 (1991+) pin 7 going from ECU pin 101 to chassis ground - I see pin 7 going from 1991+ Auto Cruise Control Unit pin 14 to chassis ground. ECU pin 101 is on C-64 and goes to ground.

If you have further questions, I'd recommend being as specific as possible and I'm sure we'll be able to help guide you through it all.

First, I want to say you are the Man!! and Thank You Thank You!! You couldn't have posted this at a better time, As my diagram reading skills are not the greatest especially when the wires and components start jumping around pages,then remembering what all the little dotted dashed lines and symbols represent gets a little confusing sometimes but I'm not too bad either , I was unsure about a few of the pins and what component they went too but your post helped me confirm I had a few wrong.
Sorry about the difficult to understand information, to be honest I wasn't very confident that anyone had a 1990 specific factory manual let alone knowing that there are quite a few differences between the 90's and 91+. Just assumed everyone would just have the 91+ or I would have asked if anyone has a pin-out diagram for the C-50,C-58, would have made my first post a lot easier to understand. I know how difficult topics like this can get so I try to be as informative as I can "too much" sometimes, it seems as I am writing my question gets intertwined in the information or its not very clear. I will try to keep my future post more to the point.

UPDATE:
Had a chat with OHM about my harness as I had some issues with what the instructions were saying I needed to connect in the car, compared to the wires I had left on the harness. What we learned was the Instructions are for harnesses built for cars using Stock ECU's and connectors. Harnesses made for cars with aftermarket ECU's will generally have less wires in the harness that needed to be connected to the car due to how they are configured.

For example on my harness I have a Brown wire labeled #2 TPS, its goes to pin #2 TPS on the C-67 (91+). But on C-58 (90) pin#2 is for the AC Clutch relay which then leaves the BROWN wire as extra but OHM told me it will not be needed to connect to the car as the wires for the TPS have already been integrated into the harness for the AEM.

Also I wont need to connect either of the Self Diagnosis Connector wires as the AEM doesn't/cant use them. Just a small oversight on their part?

For the "C-67 (1991+) pin 7 going from ECU pin 101 to chassis ground I see pin 7 going from 1991+ Auto Cruise Control Unit pin 14 to chassis ground. ECU pin 101 is on C-64 and goes to ground". This is what OHM has in their instructions. This one is a perfect example of the connectors/wires jumping around.

One thing I noticed that is incorrect on C-58- [04] - Brown w/ red, ECU pin 3 to Combination Meter Pin 6 for Boost Pressure Gauge. I see a Black w/ Red ECU pin 4 to Combination Meter Pin 6 for Boost Pressure Gauge. Maybe Mitsu made a error, I checked a few other places and they show ECU pin 4 as well.

Not much of an Info update for getting this installed in the car, more of a working out little issues so the actual install goes smoothly. Now that I have the correct information for C-50,C-58 and from OHM, I plan to soon start removing the old harness and install the OHM harness. Just need to double check a few more things.

 

[19Eclipse90]

Truly no worries, I commend you for working at it and trying to figure it out. That's the best way, IMO, that you'll learn it!

Clearly, we all make mistakes. You're correct on C-58 - [04] --- that's my error in transposing BR as brown w/ red instead of black w/ red. Brown with red would show BrR. It is, in fact, black with red and I have corrected this in my post. Onto the rest of this section, that "pin 4" is not on the ECU, it's simply showing pin 4 of C-58. Pin 4 of the ECU is a white wire that goes to pin 1 of the O2 sensor and changes to black to run to the O2 Sensor Check Connector. I provided this the other day for another member but here you can see at the lower right-hand side that pin 3 of the ECU runs through pin 4 of connector C-58, through pin 10 of C-61, and to pin 6 of the Combination Meter for the boost "Pressure" gauge.

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Regarding C-67 (1991+), refer back to the Configuration Diagrams section of the manual. You will note that the MPI Control Unit is using C-64, C-65, and C-66. C-67 is a "Control Wiring Harness and Body Wiring Harness Combination". You're referring to a pin 101 on C-67 which does not exist in Mitsubishi's notation (again, this is 1991+):

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​

Are you saying your OHM harness has a brown wire for pin 2 for what would be C-67 and would then go to pin 2 of the TPS? If so, I would definitely go with what they say. All that wire is doing is running to the Auto-Cruise Control Unit (Cruise Control ECU / Brain) on 1991+, so I do not see its relevance on a 1990. For reference, from the article I put together, here's how I repopulated the 1991 connector on the 1990 harness:

'90 -> '91+
2 -> 4
3 -> 5
4 -> 9
5 -> 10
6 -> 11
7 -> 12
8 -> 13​

I would assume that they either were not aware you were using an AEM or, yes, it would be an oversight. The self-diagnostic connector is really only beneficial with the original ECU, as far as I can see.

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1990 Cruise Control

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[92AWDHX40]

Good read i have installed a auto harness in a manual, 1g, and a 1990 harness into a 91 a just ha and ri make some changes, glad you making sense of it .

 

[9 T GSX]

Thanks for clearing this up,I was just making sure that we were both looking at the same diagram for the boost pressure gauge. In this diagram page 8-71 is there any relation to pins 4 and 8? Are they both on C-58 it looks like they should be or else there would be another connector next to 4, correct? What does the dotted line between them represent if anything.
You mentioned there is no ABS in a 1990, Are you saying that none of the 1990 cars had it at all or just that if anything on my harness had wires going to something ABS I could ignore it because it probably wont have it? Curious due to the manual having an ABS section? Perhaps its just a default thing when they make these manuals?

I can see where the confusion for 101 on C-67 comes in. I might have worded it wrong but it should be Pin # 7 on C-67 which then goes to ECU pin# 101 Ground to Chassis.Could
you confirm.
I remember reading the symbols and that [7] in black at the bottom that has 2-B on it has a meaning, something about the wire is continued on the next page, but in this case it goes from (Page 75 then to 123) if reading this right. You can see #7 on the C-67 connector even though it upside down.

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Yes my harness has a Brown wire that is suppose to go into Pin 2 on C-67, But OHM has already wired the TPS for the aftermarket TPS I will be using. You can see the Brown #2 wire in the photo above,its right under the #10 blue wire. When I talk to OHM again I will find out which loose wires I have get installed or not. As of right now, out of the 4 loose wires I have, only 3 will need to be connected to the car. I really think they just overlooked this during the assembly process, could have been on auto pilot thinking OHH DSM harness, ok it gets this,this and this. Because when you build these harnesses they have many options to choose from including which ECU you will be using.

Might be a bit of a stall on updates as my job is ramping up on work so many hours ahead for the next few weeks but I will update when I have something to share.

Thanks for all the help so far.

 

[19Eclipse90]

The dotted line between 4 and 8 on 8-71 indicates that the pins are on the same connector, C-58. It's a bit tricky as you can see below that at the ECU that it appears there is a dotted line between pin 64 on C-56 and pin 3 on C-57. This obviously does not fit with Mitsubishi's notation and checking the 1991+ manual, we see this was corrected and can safely assume it was an error in the 1990 version.

As far as I am aware, ABS was not found in the 1990 model year. I've checked against ASA in the past and did not see an ABS modulator pre June-1990. What manual are you referring to that has an ABS section? My 1990 hard copy doesn't have it and the 1990 Technical Service Manual doesn't show it. What's more, the ABS modulator sits where the 1990 cruise control sits - hence why they moved the cruise control unit to the firewall in 1991.

You're talking about 1991+ C-67 pin 7, right? I provided the diagram at the end of my previous post - pin 7 connects pin 14 of the Auto-Cruise Control Unit to ground. That 7 at the bottom is showing you a grounding location within the vehicle - the black squares with white numbers are grounding locations. See highlighted section below and the associated locations.

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​

 

[9 T GSX]

Thanks for the explanation for the dotted lines, Don't think I would have never figured that one out.

I have a 1991 Eclipse factory manual that I have had for years. I recently bought a brand new 1990 Laser factory manual and in it it there is a ABS section. The one thing that is different between the 2 manuals is the 91 Eclipse is 2 separate books Volume 1 and Volume 2 and the 90 Laser is both volumes in 1 its literally 6" thick.

Yes I was referring to C-67 91+, Looking at the 2 pictures of the manual in my last post I was suggesting that pin 7 has a (2-B identification) connects pin 14 of the Auto-Cruise Control Unit to ground (yes), on page 123. Then looking at Page 75 Lower left corner it shows C-67 again showing (2-B ) which I was assuming was Pin 2 on C-67 but it also connects to ECU pin 101(Ground).Which is what I think OHM is suggesting as well, as it would make sense because pin 2 on C-67 is the TPS. If that is the case then this must be the ground from the TPS sensor thru those 2 connectors then to the ECU 101?

I guess I misread the black square with a number with the upside down triangle with a letter, as in your diagram in your last post top right corner under "resistor". It say "Indicates the diagram is continued from (upside down triangle A) on the previous page"

 

[19Eclipse90]

The 2-B "identification" is showing the wire size for the indicated run of wire.

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So, at some point between pin 7 of C-67, the wire is enlarged - most likely due to multiple components using the same grounding location, from 0.5mm^2 wire to 2mm^2 wire.

Whether or not any 1990 manual mentions ABS does not do anything for us here unless your car has ABS. If it does, then it is something to worry about. If not, then it's a moot point. Not that it means anything, but the 1990 hard copy I am currently referencing is the Laser / Talon version and it is a two-book set, the second of which is Electrical.

Refer to this snippet of page 75:

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Each of the boxed in connectors C-17, C-64, C-66, and C-67 are provided, in this instance, in their full pinout schematic form at the bottom left of the page for reference because there is not sufficient space within the drawing to place the full pinout schematic. Easily the best example here is C-66, where you can see multiple pins (6, 8, 10, 11, 14, 15, 16, 17, 19, 20, 21, 22, 23, and 24) shown on the diagram. Imagine if you had the full pinout schematic for C-66 at each pin and what an absolute cluster that would turn into. I added the red arrow to indicate that on the next page, you'll see that the dotted line will continue across to C-66 as well.

Here also you can see that ECU pin 101 is on C-64 and, along with 104 and 106 on the same connector, all go to the same grounding location (location #7) as pin 7 of C-67.