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1984 Z28 ECM Positive Battery Wire Question

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Old Mar 5, 2024 | 11:45 AM
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ryguy32789's Avatar
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From: Chicagoland
Car: 1984 Z28
Engine: 305 HO
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1984 Z28 ECM Positive Battery Wire Question

I'm trying to un-hack this 1984 Z28 I bought and was hoping to get some guidance on this wire. It's orange, is on the passenger side of the engine bay, and runs directly to the positive battery terminal. Somebody had cut it and spliced in a switch to operate the side marker lights, which is why that wire crimp is on there. From looking at wiring diagrams and old threads, I think this is the ECM power wire? Is that correct? And is this a fusible link, or supposed to contain a fuse? Mine is just caked full of green corrosion. I was going to cut it out and solder in a new insulated spade connector, but wanted to make sure I'm not going to fry something running this without a fuse.

Also the radiator fan won't kick on when the car is hot, but it will kick on when the A/C is on - could this cut wire be related to that problem?


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Old Mar 5, 2024 | 12:11 PM
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gt4373's Avatar
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Car: 1984 Chevrolet Camaro Z28
Engine: 5.0 Liter 4-BBL V8 High Output
Transmission: 5-Speed Manual
Axle/Gears: 3.73
Re: 1984 Z28 ECM Positive Battery Wire Question

ECM Power Plug






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Old Mar 5, 2024 | 12:59 PM
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ryguy32789's Avatar
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Re: 1984 Z28 ECM Positive Battery Wire Question

Originally Posted by gt4373
ECM Power Plug
Thanks - do you know if it's a fusible link? Or is that just a harness connector?
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Old Mar 5, 2024 | 01:17 PM
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John in RI's Avatar
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Car: 1984 Camaro Berlinetta
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Transmission: T56 6-speed
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Re: 1984 Z28 ECM Positive Battery Wire Question

If there is a fusible link ( I think there should be ) than it will be on the battery side of the plug. ( Battery- then Fusible Link- then Plug) The plug itself is the main power supply for the ECM.



*I'm guessing an HO car if it's got an electric fan ? If so the ECM doesn't control the fan,.. it's done by a temp sensor and a relay. There is also a switched ground sent to the relay from the AC control head when AC is active. ( FYI: The head mounted switch will probably not turn on the fan until temp reached about 240. )



Hope that helps !

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Old Mar 5, 2024 | 01:31 PM
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ryguy32789's Avatar
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Engine: 305 HO
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Axle/Gears: 3.73
Re: 1984 Z28 ECM Positive Battery Wire Question

Originally Posted by John in RI
If there is a fusible link ( I think there should be ) than it will be on the battery side of the plug. ( Battery- then Fusible Link- then Plug) The plug itself is the main power supply for the ECM.

*I'm guessing an HO car if it's got an electric fan ? If so the ECM doesn't control the fan,.. it's done by a temp sensor and a relay. There is also a switched ground sent to the relay from the AC control head when AC is active. ( FYI: The head mounted switch will probably not turn on the fan until temp reached about 240. )

Hope that helps !
Thanks - that does help! It is an HO car. I think I see the fusible link too now that I'm looking at the harness again - I thought it was a factory wire splice initially. So I'll just solder in a new connector for the ECM circuit, and I'll see if the fan turns on by grounding the sensor plug.
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