Junction Block Behind Battery - Team Camaro Tech
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post #1 of 6 (permalink) Old Aug 7th, 06, 04:58 AM Thread Starter
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Junction Block Behind Battery

There is a junction block on the radiator support behind the battery on my '68 vert. It connects to a pigtail on the positive battery terminal. Does this block have anything to do with starting the car? In other words, what exactly does this block do??

Dan
'68 Camaro Convertible

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post #2 of 6 (permalink) Old Aug 7th, 06, 06:19 AM
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Re: Junction Block Behind Battery

This junction block is the main power source for the electrical system. It is a junction of battery power to the horn relay buss bar.

This wire supplies the entire current load from the battery when the engine is not running. It also supplies charging current for the battery once the engine starts and alternator is kicked into gear/turned on.

This wire supplies solenoid power to "pull in" the starter drive and connect the switch to connect the battery directly to the starter motor.

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post #3 of 6 (permalink) Old Aug 7th, 06, 06:22 AM
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Re: Junction Block Behind Battery

Dan, Everett's explaination is right on.
There is full info on that in the "what it is, Where it is" sticky.
EVERYTHING except the actual current to turn the starter motor goes thru that.





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post #4 of 6 (permalink) Old Aug 7th, 06, 06:37 AM Thread Starter
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Re: Junction Block Behind Battery

I'm confused:

Everett says:
"This wire supplies solenoid power to "pull in" the starter drive and connect the switch to connect the battery directly to the starter motor."

And Jim - you mentioned, "EVERYTHING except the actual current to turn the starter motor goes thru that."

So, does the wire to the junction block need to be connected to start the car?

Dan
'68 Camaro Convertible

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Last edited by dschribs; Aug 7th, 06 at 06:49 AM.
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post #5 of 6 (permalink) Old Aug 7th, 06, 07:21 AM
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Re: Junction Block Behind Battery

The positive battery cable attaches to the BIG LUG on the solenoid.
The starter motor attaches to another BIG LUG on the solenoid. (This is the post that saticks out of the lower edge of the solenoid and attaches to a lil tab coming up out of the starter motor with a lil screw)
inside the solenoid is a copper disk that connects those 2 BIG LUGS together when the solenoid is "pulled in" (as Everett said)

The purple wire that attaches to the inner small lug on the solenoid puts power on a coil in the solenoid, this is what "pulls it in."

The purple wire (what happened to your other post where I explained all this and gave you some steps to take to troubleshoot the problem? I think you have 3 posts running on the same problem now!) gets it's power thru the following path:

Battery
small pigtail lead on battery cable
junction block behind battery
12 guage red wire under core support to horn relay
12 guage red wire with fusible link from horn relay to fuseblock.
12 guage red (I think) wire to ignition switch
start terminals in ignition switch
purple wire to neutral safety switch
neutral safety switch
purple wire w/white stripe to inner small stud on solenoid

The clicking noise you here is the starter solenoid "pulling in."

Your car is not cranking because either:

The solenoid is not pulling in all the way and not making the connection inside the solenoid

or

the battery and the large pos and neg terminals and the solenoid are not delivering enough power to turn the starter motor.

What happened to that other post?





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post #6 of 6 (permalink) Old Aug 7th, 06, 07:48 AM Thread Starter
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Re: Junction Block Behind Battery

Thanks Jim
I didn't mean for this post to cross over with my other one on the starting issue. I was just looking for some more info on that junction block. Just so I could become more educated on what that block actually is used for. I should have re-read your response to my other post. My fault.

FYI - On the starting issue. The wire that goes to the smaller terminal on the starter had tons of breaks in the insulation. One break in the insulation was right near the block and the bare wire was basically resting on the motor. I changed that wire last night. I'm going to button it all up tonight and hoepfully I'll be good to go.

Thanks!

Dan
'68 Camaro Convertible

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