resistor/diode in parking break wiring

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lilhows340

lilhows340

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Hi everyone
I've been working on the wiring of my 72 Demon. Got most of it worked out. Found that there is a resistor/diode in the parking break circuit and also goes to relay under glove box. Don't know what either is for. The wiring diagrams I have are little confusing there.
thanks Jeff
 
Can you post a screenshot of a crop of the diagram and possibly the wire number?
 
I call it a resistor/diode because it ohms out open in one direction and has resistance in the other. I will try and get pic after work.
 
lilhows340 said:
I call it a resistor/diode because it ohms out open in one direction and has resistance in the other. I will try and get pic after work.
Click to expand...

LOL that is exactly how a good diode tests. The reading will vary as they "screw with" some multimeters. Most decent modern meters have a separate dedicated diode test. Diodes are like water check valves.........they allow current flow in one direction but block current in the other direction
 
"In the parking brake circuit" puzzles me. Remnants of a add on trailer brake maybe? I've tied those to the foot operated brake lamp switch but not park/brake warning lamp.
 
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The brown lead goes to the relay under dash
 
Messed that up a bit. The brown lead goes to relay, the plug in wire goes to to harness and rings out to dash and brake balancer and the other to e-brake. The only thing I can see its for is back feed off relay. hmmmm
 
It is all factory had to pull the goo and hockey tape off it. This car did have seat belt sensors in the seats.
 
My '72 Demon had that (diode) also. I thought it was an add on by the PO and removed it. I probably messed up but everything seems to work fine. I will be interested to see what it is for. Maybe I will need to reinstall it. OOPS!!!!
Yote
 
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Well the blue lead off the relay goes to the brake fuse can't see where the gray lead goes. Not to the brake light switch or the wires broken in the harness. Maybe it turns on warning light if the fuse blows.
 
This is seat belt relay "I think."

But it does not match "quite" with what you have, at least for color

See Valiant instrument panel wiring, the 72 Plymouth manual you an download from MyMopar, page 8-152, there's an inset for the seat belt relay/ manual transmission:

The diode by the way is between the "diamond 7" and "diamond 8" symbols

Only other diode I know of was used in the headlights on/ key buzzer circuit

seatbeltrelay.jpg
 
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"Bulb test circuit"
It would stay in with the seat belt warning.diode keeps from feeding seat belt lamp in the event of parking brake use.
 
That is perfect other than there is only one dbl* but that could be tied in up stream. Going to look closer to mymopar wiring diagrams just to see where gy lead goes and original br/y* thats not used. Should just be able to to finish it off and move on.
Thanks for all the help
Jeff
 
I was going to ask last evening if this was manual trans build? I know brown w/ yellow tracer is typical to neutral safety switch signal to starter relay but it wouldn't be related to park brake in automatic.
I decided asking more questions, injecting theories wasn't necessary. Someone here knows exactly what/why/how this is.
 
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