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1G Unknown Coolant Plugs and other

jlust07

Probationary Member
12
1
Aug 25, 2022
Pullman, Washington
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This plug has a green and white wire with a green and yellow wire. It goes through the firewall to the dash connectors. (NOT THE ECU)

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Second plug I am not sure about is this 4 pin, it looks like it exits the harness near the Idle speed controller, it has 4 blue wires. Couldn't find a spot to plug it in with my car.

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I was also curious if someone could verify this image. I had previously plugged the first plug shown in this post into number 6, which at the time I had assumed to be the temperature sensor. Although following a wiring diagram, the temperature switch goes to a yellow green, and green and black wire. If anyone has information on either of those too plugs this would be greatly appreciated. If anything I want to make sure I'm wiring up the ECU water temp up correctly .
 

19Eclipse90

DSM Wiseman
5,305
1,173
Sep 29, 2003
OKC, Oklahoma
First is for your A/C’s dual pressure switch. This is by the main fuse box in the engine bay. It is physically the same connector as #6 in the diagram you’ve posted but, as you note, there’s different wire colors
Second is for the cruise control.

The diagram is correct, though it may be more helpful if it did note wire colors. Maybe I’ll revise it one of these days…

I don’t know what year 1G you have based on your post, but this thread would be helpful regardless, even though it is focused on the 1990: 1990 Engine Control Wiring Harness
 

jlust07

Probationary Member
12
1
Aug 25, 2022
Pullman, Washington
First is for your A/C’s dual pressure switch. This is by the main fuse box in the engine bay. It is physically the same connector as #6 in the diagram you’ve posted but, as you note, there’s different wire colors
Second is for the cruise control.

The diagram is correct, though it may be more helpful if it did note wire colors. Maybe I’ll revise it one of these days…

I don’t know what year 1G you have based on your post, but this thread would be helpful regardless, even though it is focused on the 1990: 1990 Engine Control Wiring Harness
If my build does not have an AC compressor, I'm assuming the first plug shown in the post will not be needed. I also don't have a cruise controller present in the vehicle, so that second plug may need to be tucked for now. I was in the process of routing the A/C dual pressure switch over to the coolant, but I now realize I may need to redo that or hide it somehow for now...
 

jlust07

Probationary Member
12
1
Aug 25, 2022
Pullman, Washington
Also my build has two wires that are labeled as coolant coming out of the ECU
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wiring diagram that I am going off of
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general front side
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back of coolant
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Front of coolant
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Left to right its AC Switch (2 wires, black green strip, green yellow strip), Coolant Temp Sensor (CTS) (2 wires, yellow green strip, green black strip), and unknown brown or yellow wire. Given the images above this one, it seem I am missing a connector wire to one of the sensors. Or one of those other "sensors" could have just been added to be a coolant stopper if you will. Could you verify this as well?

AC would go to number 6 (also, which wire goes to which side of the plug), CTS -> yellow green strip 5, green black strip -> 4?, unknown ...

Thanks for the help!
 

jlust07

Probationary Member
12
1
Aug 25, 2022
Pullman, Washington
First is for your A/C’s dual pressure switch. This is by the main fuse box in the engine bay. It is physically the same connector as #6 in the diagram you’ve posted but, as you note, there’s different wire colors
Second is for the cruise control.

The diagram is correct, though it may be more helpful if it did note wire colors. Maybe I’ll revise it one of these days…

I don’t know what year 1G you have based on your post, but this thread would be helpful regardless, even though it is focused on the 1990: 1990 Engine Control Wiring Harness
Does that mean that there are two ac compression switches? One that is connected to the coolant and one that is connected to the compressor by the fuse box?
 

19Eclipse90

DSM Wiseman
5,305
1,173
Sep 29, 2003
OKC, Oklahoma
If no cruise or A/C, you can tuck both of the connectors in the original question without affecting anything. You also do not need to connect wires to the #6 switch in the diagram as it is only used for the A/C system. If you insist on connecting the wires to that switch, either wire could go to either pin. It was originally wired, if you’re looking at the switch dead on with the latching pin at the top, green w/ yellow on the left and black w/ green on the right.

Your thermostat housing definitely has one extra temp sensors for the gauge unit (single spade). Assuming they both work, you can use either one of them for the gauge.

The dual pressure switch and the A/C temperature switch are not the same so, no, there aren’t two of them. They do use the same connector and both work with the A/c system but their functions are not the same.
 
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