My stang has developed gremlins - help, please

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Animal Lawyer

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So after driving for two hours after dark my headlights started blinking. I remembered reading about it and searched the forums and figured it was time to add in the auxiliary harness and relays . I plugged, and nothing, it didn't play. I tried to start the car, nothing. No power, no clicking, nothing. I disconnected the new harness (I had attached it to the hot terminal of the solenoid), still nothing. I shorted the starter pin, it started to turn over. Took it out of gear, went the start it, by key, nothing. tried shorting, nothing. jiggled the wires and checked that the push on terminals were snug, shorted again, started. turned off the key, stopped, restarted with key, success, but no under dash lights, no map light, no radio. checked fuses, all seem good. Jiggled wires at solenoid and checked for broken or disconnected wires, still no change. Everything else works, all lights, horn, lighter, clock, heater, wipers, convertible top and all gauges work.  Jiggled wiring by solenoid a few more timed, no change. I'm stumped. The wiring under the dash seems like a rats nest, with multiple splices, an additional blade fuse and no rhyme or reason, but until this morning everything worked.

My options -

1.Pull the harness and rewire everything and be done with it once and for all, negative is time and cost (new harness is expensive and once I pull it out I'll be redoing it for month (if not years))

2. Start at the battery and try to do a continuity check on each and every wire (I am assuming there is a broken wire I moved while attaching the new harness to the solenoid and that is what is depriving the courtesy lights and radio power), negative is time and without a plain english list of what wire (by color) attaches to what I will be 80 before I have traced everything down.

3. Figure out what wire inside the car controls the courtesy and map lights and run a new unswitched wire to the door switches (and hope the light switch also turns them on with this fix) and a new switched wire to the radio and be done with it. Not the best solution (in that whatever caused it is still there) but if everything works (and the car doesn't go up in flames) I'm good with it.

Des anyone have any other suggestions or does anyone have an easy to understand diagram (I have the  Scott Drake wiring diagrams, they are not, as they advertise easier to read, nor can I figure out where the correct wires are on the diagrams or the colors or connections) of the under hood wiring (especially everything by the solenoid and VR) or a suggestion of what color wires to look for and check?  The car runs well and drives, everything else works but I need my radio (interior courtesy lights, while nice are less necessary).

Please help,

Thanks

Rich

 

midlife

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Sounds almost like the battery cables (+ and/or -) is not making contact or has corroded terminals.  I'd start there. 

 

Animal Lawyer

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I will check it tomorrow, does anyone have a diagram (or, even better a list, of what wires are attached to each terminal of the solenoid?

 

Kilgon

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I will check it tomorrow, does anyone have a diagram (or, even better a list, of what wires are attached to each terminal of the solenoid?
Go to the 7173 Wiki tab at the top of the page and you will find the wiring diagrams there.

 

Animal Lawyer

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Go to the 7173 Wiki tab at the top of the page and you will find the wiring diagrams there.
thank you, that diagram in actually readable and has an index (as opposed to the scott drake ones)

 

Animal Lawyer

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Do you have gauges or lights
gauges, all are working, as an added bonus, taking the headlights off the switch wiring has the added benefit of increasing the instrument lighting, I can actually see the gauges at night, now

 

Animal Lawyer

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A few observations and a few questions:

Since the issue my dash lights are working better (brighter) but I am assuming that is as a result increased voltage due to the headlights no longer drawing current from the switch. The dash lights are still not quite bright enough, but if I turn the dimmer past the detent for the interior lights they become even brighter than the max setting (just before the detent). 

The courtesy lights & map light are inop whether I open the door or turn them on using the light switch. I therefor I am thinking it must be a ground problem, (otherwise one of the 2 power sources (headlight switch or door switches should work (similarly the map light wont work directly from the switch on it, or from the door or headlight switches).  If the ground is the issue does anyone have an idea where (location and what color wires) I can run a new ground for those circuits?  Seems strange that the only ground to suddenly stop working is that circuit.  Any ideas on what to test, rewire, kludge would be helpful. I'm going to run a new power and ground to the radio this afternoon, I need my music!

Thnks in advance

 

Don C

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Is your battery properly grounded? The ground cable should run from the negative battery terminal to the bottom screw on the voltage regulator (for the chassis ground) and then onto a bolt on the engine block. A few forum members have also added a ground wire from the rear of the engine block to the firewall just to insure the chassis is well grounded. The only thing that is common to all of the lights you mentioned, other than fused power, is the chassis ground. Each of the bulbs get their ground from a ground point near the bulb.

Did you check the fuses with a multimeter? Old glass fuses can look good, but corrosion inside the metal caps can cause the fuse element to lose contact.

 

Animal Lawyer

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Did you check the fuses with a multimeter? Old glass fuses can look good, but corrosion inside the metal caps can cause the fuse element to lose contact.
No just a continuity tester/light

 

Don C

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As long as your test light lit up on both ends of the fuses you should be good, which leaves the grounds or wiring/wiring connectors and switches. 

You may have to start at the headlight switch and trace and check voltages on the black with light blue stripe wire, which should have voltage on it when the headlight switch is turned to the courtesy light on position.

 
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Animal Lawyer

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You may have to start at the headlight switch and trace and check voltages on the black with light blue stripe wire, which should have voltage on it when the headlight switch is turned to the courtesy light on position.
do you know where that wire goes?  Are the door switches completely separate or do those wires join with the black with light blue stripe wire before connecting to the courtesy lights>

 

midlife

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I've seen an issue where the courtesy lights won't work because the black/blue wire that chains them together is broken.

On the other hand, your dash lamps being brighter past the detent suggests that the rheostat is dirty/corroded/wiper not making good contact.  And you know what else goes through the headlight switch?  Yup, the black/blue wires for the courtesy lights.  When the knob goes past the detent, those underdash courtesy lights should go on.  They get their power from the green/yellow wire either at the door jambs or the (guess what...) the headlight switch.  Hmmm...

 

Animal Lawyer

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I guess I will pull the headlight switch and start there. Weather kept me from troubleshooting yesterday, when I get a few minutes (I really hate how work interferes with my car time) I will pull the radio to check for power there and the light switch to check for power at the black/blue and green/yellow wires at the switch. 

 

Animal Lawyer

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So, I pulled the radio and tried the hot lead grounded to the brake pedal, nothing, then I tried a known good line and still nothing. I changed the ground to the cigarette lighter and both had power. So I opened the hood and checked ground to the block, good and to the fender and cowl, all good. Seems I have good ground in the engine compartment but not inside the car? This I really don't understand. Any thoughts, ideas, suggestions?

Do I run a ground directly from the battery to the two courtesy lights, the map light and the radio?

 
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Don C

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If the cigarette lighter provides a good ground your dash has a ground. The cigarette lighter does not have it's own ground, the metal case gets it's going from a common ground point on the dash. The brake pedal is not a good ground, it is suspended on nylon bushings, has a rubber bumper, the push rod runs through rubber.

 

midlife

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If the cigarette lighter provides a good ground your dash has a ground. The cigarette lighter does not have it's own ground, the metal case gets it's going from a common ground point on the dash. The brake pedal is not a good ground, it is suspended on nylon bushings, has a rubber bumper, the push rod runs through rubber.
That's incorrect.  Every 7123 has a two wire female spade lead very close to the cigarette lighter 90* connector that provides the ground for the lighter.  That spade lead is tied into every other ground (if the wires aren't broken) via 2 ring connectors on the passenger side of the car.

 

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