Low brake warning wire

Fireguyfire

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So I’ve dropped my restored 440 engine back into my 70 300 convertible and I’ve tested and reinstalled the factory wiring harnesses on the entire car. The previous owner had installed a generic painless system and the car had all sorts of electro gremlins; luckily he kept all of the original harnesses which I’ve confirmed are good.
Anyways, on the main firewall connector block on the engine bay side tge is a black wire cut off about 3” long. According to my colour wiring diagram it should go to the “low brake warning switch”.
I haven’t had a chance to have a close look yet, but I wanted to confirm that this switch would be on the brake brake proportionaling valve?
And if so, what type of connector does it need there; the 90 degree Rubber boot style?

ABA284AF-8D88-45CB-B74F-9C9852B7DC26.jpeg
 

1970FuryConv

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I haven’t had a chance to have a close look yet, but I wanted to confirm that this switch would be on the brake brake proportioning valve?
Yes.
 

Fireguyfire

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I also noticed that my 6 gauge red wire with the fusible link that goes from the positive battery terminal to the batt connection on the starter relay is missing.
Any suggestions on how I can go about making up a wire? Can I buy fusible link wire to splice in?
 

Big_John

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There is no proportioning valve on a '70 300.

There is a "hydraulic safety switch", sometimes referred to as a "distribution block" that the wire attaches to. It is not a proportioning valve, not even close in function.

If the car has disc brakes, there is a metering valve in the front brake line, but the wire does not connect to this.

I strongly suggest getting a REAL wiring diagram from a factory service manual and that will not only show the correct wiring, but will explain the braking system. Download a free version here:
Service Manuals – MyMopar

While I will never suggest doing business with this guy, he explains the differences well. I've set this to start at the safety switch explanation which goes into explaining the front metering valve, but watch the entire video too.

 

Big_John

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A picture of the brake wire... This happens to be on a '71 B-body and it's a pic I found on the intrawebs.


1650767150827.png

I also noticed that my 6 gauge red wire with the fusible link that goes from the positive battery terminal to the batt connection on the starter relay is missing.
Any suggestions on how I can go about making up a wire? Can I buy fusible link wire to splice in?

The fusible link has to be smaller than the wire it's protecting. Basically add "4" to the size and you have the size fuse link you need. BUT!!! There is no fusible link in that #6 main battery wire.

There is a fusible link in the #10 wire that runs from the battery. #14 would be that size fusible link. Refer to the FSM, page 8-93.
 
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