Just wanted to give back a little, as I am tackling my swap harness there is good information from users all over that I used, and I wanted to compile everything I have researched to one spot in some easy to use diagrams.

If you want to re-pin your engine harness connectors for a swap, or if you are trouble shooting and find you need to replace some corroded pins or broken wires in your engine harness, then this thread will be useful.

A note that my car is a base model 85 originally with a 2.5, swapped to a 2.8, now going 3900. So my wiring colors may not totally match yours.

C203 connector, backside view:




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C500 connector, backside view:




Here is an actual image of the two connectors for reference, C203 on the left, C500 on the right.



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And here is a full list of the pins used in the C203 and C500 with all the options for different wire sizes especially if making modifications. My C500 only had Metri-Pack 280s and 480s, but I think there are some spots that fit 150 series pins.

280s are 2.8mm wide spades, 480s are 4.8mm wide spades, and 150s are 1.5mm wide spades.

The C203 uses the same Metri-Pack pins, but they are female 280s. On the body harness side connectors, they are male 280s, just like the majority of pins in the C500.

C203 PINS

280 Series (Female)

12-14awg: 12162597
https://www.mouser.com/Prod...7jpqap4wGEtxsg%3D%3D

18-20awg: 12034046
https://www.mouser.com/Prod...1xzQG8c%2FZrwg%3D%3D


C500 PINS

150 Series

17-20awg: 15344866
https://www.mouser.com/Prod...Obt1XEOt6rAAOA%3D%3D

280 Series

10-12awg: 12084586
https://www.mouser.com/Prod...FL2p3rKY3shgCg%3D%3D

14-16awg: 12020116
https://www.mouser.com/Prod...FL3bGErK9Bv5ow%3D%3D

18-20awg: 12034047
https://www.mouser.com/Prod...FL0P6hZQKNlzpg%3D%3D

480 Series

12awg: 12065197
https://www.mouser.com/Prod...dyd%252BacawLA%3D%3D

14-17awg: 12065196
https://www.mouser.com/Prod...5AK9w5s05garzJQOAAFT
18-20awg: 12020119
https://www.mouser.com/Prod...t2KKItj3GKFjBA%3D%3D

Let me know if there are errors and I will update.

[This message has been edited by zkhennings (edited 02-11-2023).]

Good information, thank you.

No problem, I have ordered all the pins I need to re-pin these connectors from the links I listed and I will update if everything fits correctly.

I may create a how-to on wiring our cars up with a Microsquirt (applies to Megasquirt too but I am using a Microsquirt), cheap and powerful with no frills, self tuning, real time tuning, free software, lots of digital dashes compatible with it, and a brand new wiring harness. Also they are designed to work with all GM hardware which is great for our application.

Are the color pin outs correct for the 2.8 ? ….just a bit confused.

quote Originally posted by zkhennings: No problem, I have ordered all the pins I need to re-pin these connectors from the links I listed and I will update if everything fits correctly. I may create a how-to on wiring our cars up with a Microsquirt (applies to Megasquirt too but I am using a Microsquirt), cheap and powerful with no frills, self tuning, real time tuning, free software, lots of digital dashes compatible with it, and a brand new wiring harness. Also they are designed to work with all GM hardware which is great for our application.

I would like to see that for sure. I am thinking about getting a Microsquirt for my 4.9. I am not worried about the wiring, but I do like to compare to how others do things.

quote Originally posted by PhatMax: Are the color pin outs correct for the 2.8 ? ….just a bit confused.

Yes they should be, my car did not have AC, and it is a manual, so that may be the cause of some discrepancy.

Update that I ordered and received these pins to rewire the C203 female side and C500 male side (engine wiring harness side connectors) I have confirmed that they all work and are the correct form factor. I ordered lots of extras.