ConcoursMustang Forums
1st Generation 1964 1/2 - 1973 - Questions & general discussions that apply to a specific year => 1967 Mustang => Topic started by: kkupec02 on April 19, 2020, 01:09:44 PM
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I just bought the car mid March and had a burnt horn contact so I had to change my steering wheel harness. Never got the car on the road yet due to brake rebuild needed so it immediately went up on blocks. I thought that I checked turn signals and emergency flasher and believed that they worked before the swap, but evidently not. I got a repro harness and installed it. I got a strong left turn signal. Weak right turn signal you can see in daylight, but also only evident in the dark, a very weak left turn signal at the same time. So the power kind of bled over to the left on a right turn signal. Flashers give me a strong left hand flash but you can't see anything on right except a very weak right flash only evident in the dark. Right hand side issues are both front and back identical. So it's the whole right hand side. I paid $200 for a new in box Ford 1967 harness, installed it and got the same thing. Where should I start the diagnostics? It must be something going on right hand side. A short? A bad ground? Thanks.
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What do the brake lights look like - even in brightness left to right? That can help rule out a ground problem.
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My booster and master cylinder are out for rebuild. So my brake switch is not attached to the booster rod right now. My wife pulled out a couple of pictures from March as the car hauler took it off the truck at night. The left brake light is strong, the right brake light is noticeably weaker. Any particular place to look for a weak ground? I will have to look at my wiring diagrams. I assume the wires are routed through relays and voltage regulator? thanks.
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ps I have a 289 GTA coupe from San Jose as well.
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Do you have a set of the Osborn Products 67 Mustang Assembly Manuals? The electrical manual has a fairly good set of drawings and schematics. If not, get a set. The 67 Mustang set is the most complete.
Jim
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Thanks. I do have the set as well as the 1967 shop manual
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That's next on my list to peruse through.
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It does sound like a ground problem to me, so let's rule it our or fix it.
You should find the common (left and right hand side lamps) ground screw on center sheet metal support in the trunk where the latch is attached. That ground should be good since one of your lights is bright.
Pull the 57 black ground off the male spade connector on the weak light. Temporarily connect a wire from the spade to the ground screw. I typically have several jumper wires with alligator clips for things like this, hopefully you can find something handy that works.
If the light is bright, your problem is with the female spade connector, or internal to the backup light connector, or at the ring lug connector (crimp) at the ground screw. You could also have a section of wire under the insulation that has multiple broken strands, which is harder to diagnose and find.
If the light is still dim, the problem is in the socket. I would swap bulbs, left and right, to see if the problem clears. If not, inspect the socket closely, you might have some corrosion in there.
By the way, the 14305 and 14290 numbers on the diagram represent basic part numbers for the two wire harness assemblies.
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I listed this as a regular 1967 problem as electrical should be similar between a Shelby and a Mustang. I am having problems with my Shelby. I attached a few pictures of my electrical. I cleaned the common ground near the trunk latch and as you said, no difference. I then checked the volts going to the good left side and it was receiving a relatively steady 0-1.0 volts up and down. I checked the bad right side and the volts were jumping all over from 0-2.6 volts. There seems to be only that trunk latch ground in the back on the Shelby's. All black wires come from the front and only ground there in the back. That ground branches to the right and left side in the back. There is no individual ground for each socket/side on the Shelby. I wonder if it is my voltage regulator? It seems to be an older "electronic" replacement?
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I then checked the volts going to the good left side and it was receiving a relatively steady 0-1.0 volts up and down. I checked the bad right side and the volts were jumping all over from 0-2.6 volts.
In a 12 V system? What am I missing here?
Jim
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It's factory 12 volt. Not sure why I am seeing spikes. Can't be regulator as it comes from front and branches to both rear lights. Should be a problem with both not just one side if it was regulator. Remember, I am having bleed over issues and weak signal on the front right side as well as the back right side. Yet the same wire from front is used on both rear lights. ??? Also, why do I have problem in front right side as well?
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Just checked rear tail lights again. Left working strong pulling 0 to 1.2 volts with bright light. Right weak lights yet pulling 0 to 3.0 volts bouncing around with even some negative readings thrown in. When I turn on left signals, no problems. When I turn on right signals, weak back light and front light weak with bleed over to left front signal as well. ie, right turn signal turns on right back, right and left front..
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The turn and emergency signals are a relatively slow frequency square wave, and this is where an old analog meter is superior to indicating what is going on. It is the sampling rate and update time on your digital meter that is not telling you what is really going on.
You will see at each bulb two wires - the black wires are the ground (57). Do the wires jumper from bulb to bulb? From the outboard bulb, does it then, like the Mustang, tie into the circuit that includes the backup lamp?
If you can install a jumper, like I recommended, from the ground screw that you cleaned up, to the bulb socket that can help you determine if there is a poor ground between the lights and the ground screw. From the looks of it, that might be difficult. I would probably pull the inboard most lamp, pull the bulb, and probe the ground pin, with an alligator clip connected to the ground screw, and then see how bright the lights are.
The other option is to pull all of the bulbs and connectors, and give them a good cleaning.
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The main harness comes in from the drivers side, left. It branches into 3 parts. One part down to left back up light. One part to left turn signals. One part across trunk to right turn signal. Then that branches to right back up light. Turn signals are on a chain. The wire goes from outer, middle inner with same wire from harness on each side. So the wire jumps from bulb to bulb. I pulled off one of the right tail light sockets. The other 2 got immediately brighter. I did this to each of the 3. It made the other 2 brighter each time. I jumped a wire like you said from the trunk ground to each bulb socket. It made no difference. Remember that all through this, the right signal light continued to turn on both the right and left FRONT turn signals at the same time. I pulled all 3 sockets on the right rear. I'll clean the sockets and replace the bulbs just in case. Maybe they sell replacement sockets as well. I then tried the right turn signal with all 3 bulbs out of the harness. No change. Right signal still turned on both right and left FRONT turn signals.
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Does this have sequential taillights? If so I would temporarily bypass that to remove it from the troubleshooting process
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No sequential lights. They didn't happen until 1968. Thanks for the help so far. I am going to go dark for a while while I do some work and order parts. I guess since the emergency flasher and turn signal relays are so cheap, I'll order them and rule them out. Especially since I have a problem in the front as well as the back. I'll get all new bulbs front and back and rule them out. Sockets I am not sure about yet, but I will clean them up. I will also do continuity checks from the left of the harness to the right in the rear. I don't know why the power feed goes from left to right with a "good" left to a weak right. Is it ground? I don't think so since I did the jumpers. Is it a loss in the power wire? I also have weak right running lights and brake lights as well as the turn signals. Again, this is true both front and rear on the right side.
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I just bought the car mid March and had a burnt horn contact so I had to change my steering wheel harness....
Explain "burnt horn contact"
If ever something shorted out and perhaps was WITHOUT a fuse (as in bubble gum wrapper used as a fuse or the likes), you risk the possibility that wiring could be melted together in the main harnesses.
Do you have any melted-looking wiring in the original steering column harness?
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One of the 2 floating horn contacts in the steering column harness had shorted. The copper top was gone, there was a burnt spot on the stainless steel horn ring under the steering wheel and it burnt up a wire in the steering wheel itself that I had to replace. There were no issues with the harness wiring when I removed it. And it has been replaced with a $200 new in box Ford harness from EBay. I had the turn signal issues before and after the steering wheel harness fix which of course still could mean wiring issues elsewhere. After the easier changes that I listed as parts come in, bulbs, turn signal flasher, emergency flasher, my next diagnostic as you say is to start checking continuity in all of the turn signal wiring for issues. I am hoping for something else but agree it doesn't make sense that for instance the back tail light wire goes from the left side which is good to the right which is bad. It is the same wire. I think that I may have more than one issue going on with the wiring. Something going on right rear, ground or power wire, and something going on in front with the bleed over of power where the right signal turns on the left front signal as well. Power bleeding over from a short? A bulb? Through a ground?
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Let's try this:
Take two pictures of the wiring connectors, one from the back side of each the steering column harness and another from the vehicle's under dash harness.
Maybe a previous attempt at a repair crossed wires somehow.
Try to pre-arrange each wire so the picture shows any tracer wire (such as "blue with yellow tracer").
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I have a column out of a parts car that everything worked on. I use it to test with by laying it on the floor and plugging it in to the car harness. It has save me several needless turn switch removals. I once got a car that had been done in a Mustang restoration shop, it had all kinds of weird stuff going on. I plugged in my test column in and all was fine. I discovered that they had reversed the order of the wiring in the plug.
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Let's try this:
Take two pictures of the wiring connectors, one from the back side of each the steering column harness and another from the vehicle's under dash harness.
Maybe a previous attempt at a repair crossed wires somehow.
Try to pre-arrange each wire so the picture shows any tracer wire (such as "blue with yellow tracer").
Wire in color/stripe should match wire out color/stripe.
Jim
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I stripped out the wiper motor wires from a 67 harness in order to build a test harness for wiper, switch and foot pedal. Also handy for resetting wiper to park.
Same concept to test out pieces with known good parts from a parts car!
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I just checked the harness both sides and it looks good. I have matching wires from steering harness side to dash harness side. I have: red steering harness to empty dash harness side (I guess this is normal). I then have orange/blue to orange/blue, white blue steering side goes to 2 white/blue dash side, green/white steering side goes to 2 green/white dash side, blue/yellow to blue/yellow, green/orange to green/orange, white/red to white/ red, yellow to yellow, green to green and blue to blue. I have all new bulbs coming in. I will clean all contacts and add grease. I have a new correct concours voltage regulator coming in as the one I have is incorrect parts store replacement. Also a new flasher relay if I can reach it from underneath. After that, I will have to go wire to wire and check continuity.
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My questions and recommendations have been an attempt to divide and conquer. Keep cutting the potential problem location in half until we get to the issue. But you might have more than one issue, and that can be very challenging.
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I agree in that I think that I may have more than one issue. I don't know why I am getting such low voltage to the lights first of all. Then there is the bleed over problem. Finally, my horns work sometime but not all of the time. So I am losing power to them off and on. It is after the dash harness as today when they didn't work, I put a jumper on the horn contacts, put a light on the yellow wire at the dash side of the connector and had power, but no horns. A little while later, they worked again. I'll start a new thread once my parts come in and are installed. thanks.
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I agree in that I think that I may have more than one issue. I don't know why I am getting such low voltage to the lights first of all. Then there is the bleed over problem. Finally, my horns work sometime but not all of the time. So I am losing power to them off and on. It is after the dash harness as today when they didn't work, I put a jumper on the horn contacts, put a light on the yellow wire at the dash side of the connector and had power, but no horns. A little while later, they worked again. I'll start a new thread once my parts come in and are installed. thanks.
You may already know this but it bears repeating that the horns and tailights etc,require a good ground to function properly. A poor ground has been the source of more then one strange symptom . In your case it could be one of the multiple problem . At the very least it is good to confirm and eliminate a ground as a culprit. For the best horn ground I make a small patch of the contact point bare metal on the radiator support side and on the horn bracket side .I then take a small wade of aluminum foil to take up gap in between the bracket and radiator support when bolted down. I coat all contact surfaces with dielectric grease to prevent corrosion. Other grounds can be confirmed and protected in a similar way.
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Thanks for the tip. I have a big tube of dielectric grease coming with the new bulbs, voltage regulator and flasher. I also have sandpaper ready to clean all contacts. I hate to keep extending this thread, but I just came up with another question. I have been reading through my Osborne manuals and the 1967 mustang, cougar and fairlane service manual as well as trying to jumper and continuity the problem. In the diag section of the service manual, I see what appears to be very similar to what I am experiencing in the turn signals and emergency flasher. I have ordered from NPD the only flasher assy listed for 1967. It seems to be a combo flasher for turn signals and emergency. Despite the fact that the electrical diagrams list them separately in the service manuals. Are they one and the same on a 1967? Secondly, the diag section of the service manual says that I may have 2 wires crossed at the 4 wire 'turn signal indicator relay' or may need a new one. This can't be the same as I ordered form NPD as I believe that is a 2 wire flasher? The NPD pics don't show the back. Is there a " turn signal indicator relay"?