Slight electrical problems

[rnrjunkie]

Hi,

Been beating on my `67 Fastback to get a few problems fixed:

1. Swap front wiring harness (fried at radiator support, no charging)
2. sfe20 (bottom) fuse blowing
3. Blinkers slow, brake light a lil late, etc.

1. I have swapped the front harness with all lights, horn, etc. working. I do have a connector that has no wires in the dash, where the previous harness was connected. After tracing the wires, one leads to the starter solenoid, the other to ground. Any ideas what it could be? It is a yellow plug with a solid yellow (ground) and solid red (solenoid.)

2. I have NO idea why this fuse is blowing...I was hoping it was related to the wiring harness, but didn't fix the problem. I have tried a fresh fuse with the turn signal harness disconnected, the light switch disconnected, radio disconnected, and of course with the front harness disconnected. Any ideas where I could look next? The dash wiring harness looks good and has no other problems otherwise. Ideas? The fuse blows immediately after inserting a new fuse. All lights, etc. work, just trying to get the harzards working properly.

3. All working great with the new wiring harness and a new flasher.

Thanks for any ideas!

Andy

 

[67GTFB]

that bottom fuse (20 Amp) provides power to the cig lighter and emergency flasher circuit .... so if you disconnected steering column connector (turn signal and emergency flasher circuits), only the cig lighter and power feed to the steering column connector (emergency flasher circuit) remain .... check around the cig lighter to see if it is shorted out somewhere ..... those two circuits are always "hot" so fuse blowing is consistent with a short in those two circuits .... but I would really focus on the cig lighter ....

good luck !!

 

[rnrjunkie]

Morning,

I've traced the schematics and you're right: the "hot" wire splits on the fused side to the cigarette lighter, the clock, and the hazard flasher which goes to the turn signal switch. At the moment my instrument cluster is out, and I did try with the cigarette lighter disconnected.

At this point I have 3 wires to test for ground: hazards, clock, and cigarette lighter.

Andy

 

[Jetsetmantony]

I totally agree with 67GTFB and RNRjunkie. They're right on the money. That's what I came up with very late last night. (Sorry, didn't want post with a mistake before checking again. You probably already resolved that problem).

The yellow plug you ask? Hmmm, do you have A/C, defogger, etc., park brake, low fuel/door ajar, seat belt warning lights/lamps? Not sure about the 67's. If you do, I have some places you could look at for identifying the yellow plug.

 

[rnrjunkie]

I have A/C and a Seat Belt warning light, although I'm not sure why either would need juice from the starter solenoid.

 

[horseballz]

Andy,
The large terminal of the solenoid that connects to the positive side of the battery is basically the main junction/main power feed to the rest of the electrical system, note that the positive side of the battery doesn't connect to anything else except at that point. The 3 other terminals of the solenoid function as:
>Other large terminal provides power to the starter when the solenoid is activated
>Small terminal near the large starter terminal provides full 12 volts to the coil while the engine is cranking at the same time that the starter gets power, and is connected in parallel to the large starter terminal
>Small terminal near the large positive battery cable activates the solenoid when it sees power from your ignition switch when the switch is turned to the start position. This is evidenced by the fact that the you can make the starter crank by placing a screwdriver or momentary switch between the positive battery connection and this small terminal.

As far as your statement in your first post:

"After tracing the wires, one leads to the starter solenoid, the other to ground. Any ideas what it could be? It is a yellow plug with a solid yellow (ground) and solid red (solenoid.)"

I don't know of any yellow or red wire that should be connected to ground!
HTH,
Gene

 

[horseballz]

Andy,
Check this link:

1967 Mustang Wiring and Vacuum Diagrams

Best to download them from near the bottom of the page as the files will open more easily for you.
HTH,
Gene

 

[rnrjunkie]

After busting out the multimeter and tracing a bit, the culprit is the (not in use) blue/black stripe clock wire going to the cluster that is grounded somewhere. I'll need to pull the ignition switch and fusebox to find the problem. At least then I can pull the harness through and fix and re-tape. The rest looks good except for a few "repairs" that could use a bit of solder and heatshrink to make them last another 44 years.

The best diagrams that I found are here:

http://1bad6t.com/diagrams/67MustangWiring01.jpg
http://1bad6t.com/diagrams/67MustangWiring02.jpg

The cigarette lighter actually connects to the + wire on the hazard flasher that comes from the fuse box.

Thanks,

Andy

 

[Jetsetmantony]

RNR, I agree with horseballz, no yellow should go to ground, at least I can't figure one to ground. How long has it been there?

"RED" does go to the Starter motor relay, (Solenoid). If your looking at it from the driver's side as it is fastened to the fender wall, it's the "right" hand "side" terminal.
Question: Is the "yellow" plug a 3 prong female or just a single? Is it for sure, "yellow"? I'm thinking there should be a yellow connector somewhere that is a Blue/RED stripe wire with this plug? How about Blue/Green stripe? We're getting there, just need precise details. Some of those wires might be really dirty and at first look might give a "false" color reading. (When "knucklehead" painted my car, he over sprayed all my wiring harnesses. It was a lot of fun removing the spray off the wiring so I could identify and hook up my rally pac and fog lamps). Provide more details and I think I/we can help you.

As for the lighting circuitry, exam for burnt out lamps still in the socket. I had one in my right hand courtesy door, and an "open" ground in the internal ground wiring for the the courtesy door light, and a positive lead shorted to ground on the driver door jam/push button, can't think of the correct name, it had to link up with the rally pac). If your blowing the same 20 amp fuse, something on that circuit is "pulling" it down and only wiring/accessories,etc., that are on that 20 amp circuit. The A/C and the seat belt could be tied into that questionable "yellow" plug with no connection.

 

[rnrjunkie]

I plan on tracing that yellow plug to see where it goes once I'm done with the fuse issue.

 

[2+2GT]

3. Blinkers slow, brake light a lil late, etc.

Was this with the engine off, at slow idle, or fast (1000+) idle? Makes a big difference. Engine off will be about 12V. Fast idle will be about 14.2V. Makes a big difference to the flasher.

 

[rnrjunkie]

Update: I pulled the fusebox out to make some sense out of what was connected to where. The Flasher relay connects directly to the bottom SFE20 fuse on the fusebox, which was grounded. After tracing the wires that also run to that fuse (cigarette lighter, clock) it was actually the flasher that was grounded. The culprit: bad flasher relay. Was grounding out inside the flasher, and then to the dash.

I still haven't looked to see what the yellow plug is for on the old wiring harness, but I'll check before I put it all back together.

 

[horseballz]

The yellow is likely for the heater/air conditioning, especially if it has a 3 hole female on the end.
HTH,
Gene

 

[Flying Dutchman]

was just looking at my harness under hood found two yellow wires one goes to battery side of solinoid and the other is at voltage reg for radio condencer