CLSTR Feed Fuse has No Power.

[jricklefs]

Im working on a 75 chevy, Project that I Inherited.   I'm currently trying to get the gauge clusther working, specifically the Temp gauge..  With Key On,  I checked the fuse panel and the CLSTR Feed Fuse does not have any power.  I put a test light on both sides of the fuse posts and nothing?   Where would this get power from?   I also pulled the cluster and put a test light on the plugs where the gauge plugs in and as I fugured, Nothing there either.    Also tried grounding out the Temp Wire under the hood and of course nothing there as i fugured there wouldn't be.   Help please.

[bd]

1975 Wiring Manual

The cluster fuse receives power through a 12-gauge pink wire directly from the IGN1 terminal of the ignition switch.  Battery power into the ignition switch arrives via two 12-gauge red wires that splice together in the harness under the dash.  Check all of the wire connections to the ignition switch and to the back of the fuse box for evidence of corrosion and/or melting/burning.

[jricklefs]

Previous Owner apparently decided that he was going to use the pink wire for the HEI Distributor that he added..... Um... NOPE!  Put it back together the right way and pulled keyed power from fuse block for HEI... Thank you for the help.. I would of never found that.

[bd]

You are quite welcome.  Glad you found and rectified the problem!

BTW, welcome to our online family!

[jricklefs]

Follow up.
Had some time to keep working on electrical on this thing and its a good thing I did.  I put a new fuse in the CLSTR FEED slot, (just in case) and happened to step out of the cab, when I saw a little smoke come from under the hood.  Followed the smoke and this wire is NUCLEAR HOT!  I started to track it down and it looks like it splits into 2 light brown/ dirty yellow, wires on the passenger side of the engine.  By the looks of it It looks like  1of them  continues down to the starter solenoid? and the other is a dead end with a C clip taped up.   I put a test light on it and it doesn't have power? so I'm confused how its flaming hot.  Thoughts.   It looks like its circuit #3. but not really sure.  Let me back up and say that this is a Project Truck I Inherited.  I don't believe  that it originally had HEI..    By the looks of this schematic It looks like I can basically cut the wire... Where it heads toward the starter... I'm confused   I'm thinking that I can eliminate half of this circuit. I doesn't look like HEI Dist Used this and it is probably causing the issue...?

[DanMcG]

It looks to me like the wire you called out is tapped into the 139 slot.

[jricklefs]

That's part of the issue, none of the schematics for this year seem to have a perfect match.    I was originally tracking down #139 but the wiring just doesn't match.  But that clip that the Mid Arrow is pointing to is on the #3 circuit.  and honestly I've never seen another clip like that.   Plus this circuit also connects to the solenoid.  So I kind of agree with you but the actually wiring says otherwise. 

[jricklefs]

bd  Do you happen to have the wiring schematics for a 74?  the 75 doesn't seem to match and I'm not sure if they are the same.
thanks.

[bd]

1974 Wiring Manual

The 1974 wiring diagrams more accurately match your truck's configuration.

The wire you tagged in the diagram is circuit 3 (Ckt 3).  Per the factory diagrams, Ckt 3 is pink with a black tracer.  It is a resistance wire that feeds less than battery voltage to a conventional (points and condenser) ignition coil while the engine is running.  The yellow jumper that continues on down and connects to the starter solenoid "R" terminal is a circuit bypass that provides full battery voltage to the ignition coil only while cranking the engine, for improved starting performance.

Ckt 3 should be abandoned and disconnected at both ends with a conversion to HEI, since HEI requires full battery voltage through a minimum 12-gauge wire for optimum performance.  The symptoms of "smoke" suggest that Ckt 3 is either being used incorrectly (severely undersized for the load) or shorted to ground.

[jricklefs]

  I feel a lot better with the second opinion.  I was going to clip the wire where I originally marked, but you are saying that I could disconnect it all together because the new setup utilizes the HEI dist. I was going to do a test run and snip it and test for voltage  or ground..

[bd]

I recommend that you verify whether that wire is being used before clipping.  Proceed with the knowledge gained to develop a repair strategy.

[jricklefs]

LOL, I was going to do it that way..   

[jricklefs]

Wire was removed. Everything thing functions properly.    However The gauge of wire that was originally  used seems a little light.  If you are going to re-purpose this circuit and hook it up the the BATT on the dist. I would recommend going to a heavier gauge.

[bd]

...HEI requires full battery voltage through a minimum 12-gauge wire for optimum performance...