WTF is this thing called?

ThinBlue502

Mustang Master
May 7, 2019
375
628
103
Ohio
4957E819-4981-4F0F-949A-572D5A918FED.jpeg

I need to replace this, I just have no idea what to call it. It’s mounted on the driver’s side inner fender just behind the battery.
Thanks in advance bros.
 
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Get a Ford one if you can
The engineers used to tell us there was a special zener diode inside that the aftermarket ones did not have
You could see this on the SBDS (if it had an aftermarket starter solenoid) We used to think Big Deal but
The Ford ones are only about ten bucks more (availability may be an issue)
 
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If you go somewhere like Advance Auto and they have an option for a less or more expensive one, get the more expensive one.
 
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Get a Ford one if you can
The engineers used to tell us there was a special zener diode inside that the aftermarket ones did not have
You could see this on the SBDS (if it had an aftermarket starter solenoid) We used to think Big Deal but
The Ford ones are only about ten bucks more (availability may be an issue)

Flyback diode. It prevents damage to sensitive electrical components by preventing voltage stored in the coil that opens the relay from traveling down to the ECU.

Any relay used on a vehicle should have these diodes. You can tell if you look at the schematic on the side of the relay.

Right side is standard relay showing the contacts and the solenoid that closes them. Left side shows the same but you can see the little side loop with the small triangles. That's the symbol for diode. Left relay is what should be used for something like a fan relay.

1642688237098.png
 
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Flyback diode. It prevents damage to sensitive electrical components by preventing voltage stored in the coil that opens the relay from traveling down to the ECU.

Any relay used on a vehicle should have these diodes. You can tell if you look at the schematic on the side of the relay.

Right side is standard relay showing the contacts and the solenoid that closes them. Left side shows the same but you can see the little side loop with the small triangles. That's the symbol for diode. Left relay is what should be used for something like a fan relay.

1642688237098.png
The diodes were in all of them not just the ECU equipped fuellies
 
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Lately, I’ve just gotten in the habit of buying Motorcraft because I got burned by other products. So it’s funny to me that I had already bought a new Motorcraft from Rockauto before I saw any further replies after the first. Thanks for confirming my choices, y’all.

Side note, that diode is inside the solenoid, right? No separate purchase needed?
 
Lately, I’ve just gotten in the habit of buying Motorcraft because I got burned by other products. So it’s funny to me that I had already bought a new Motorcraft from Rockauto before I saw any further replies after the first. Thanks for confirming my choices, y’all.

Side note, that diode is inside the solenoid, right? No separate purchase needed?
Right it's internal
 
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So I found a Motorcraft locally, installed it today. No issues with swapping the old one out.

As soon as I touched the negative terminal to the battery, the car tried to start. I hadn’t connect the coil wire to the distributor yet so it didn’t start, just scared the sht out of me.

What did I do wrong, please?
 
Something is wired wrong or your ignition switch is faulty. There is likely a constant 12v going to the signal tab on the new starting relay that should be getting power only when the key is in the start position.
We need to go back and ask -
1. What happened that the old one failed spectacularly? Did the starter keep running long enough to melt it?
2. What did you change to make it not work right?
 
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