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1967 GT500
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Discussion Starter #1
Is there a place where I can find all of the 1967 ground points without searching through each page of the Osbourne electrical manual. I am sure to miss some and I am starting there for my electrical problems. Thanks.
 

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Your main one is going to be making sure you have a good engine ground strap to the firewall.

What are the electrical problems, because there's no point in telling you where the grounds for the dome light is, for instance, if you're having an ignition issue. Most electrical things on the car are going to have their own ground.
 

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Discussion Starter #3
I've already bothered a lot of people and have a lot of tracking to do. In a nutshell, I have low and unequal power to horns, headlights, tail lights, brake lights, back up lights, emergency flasher, turn signal lights as well as bleed over right to left front and back. I can go through the Osborne manuals if that is the only reference. The car starts and runs fine.
 

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A bad ground on a light bulb is not going to affect the horn, and a bad ground on a horn is not going to affect your radio, and so on. They are unique as Lizer said.

When you have such a broad range of symptoms you need to focus on what is common. We need to look at the grounding as well as the power source.

Starting with the common ground, there is not much really, so it should be easy. You have the large gauge cable from the battery to the engine, which we know is good because you can start the car, and there is no larger load than that. Then you have the ground strap between the engine and the firewall. You can of course remove it and clean all of the surfaces and hardware. A better option though is to measure voltage between the starter relay mounting screw and the battery negative post. Should be zero. Then turn on the blower motor or engage the cigarette lighter and measure the voltage again. If not near zero, job #1 is to clean up the engine to firewall grounding. If needed replace the strap/wire. Clean or replace hardware. Clean the engine and firewall mating surfaces. Please report back on this.

Once you have the battery to engine to body ground all set, turn to the positive power side. Don't jump the gun and skip over the ground checks. The battery large gauge cable to starter relay cable is common for engine starting and everything else, and we know that is good because your car starts fine. However, from the starter relay, power to the motor starter and power to the fuse panel are separate. The cable and connections to the motor starter are fine, so we turn to the power feed going to the fuse panel. I would start by measuring the power at one of the fuse clips on the fuse panel. Reference a nearby ground. Don't drag a reference ground all of the way from the battery, we want a true test. Then turn on the blower motor or engage the cigarette lighter or blow a horn, all of which are relatively large loads. What was the voltage at the fuse panel before and after the large load? Please report back on this.

Based on what I'm thinking from your multiple posts on the topic, I suspect that we will find one or more problems based on the diagnostics above. The next steps are based on the results that you report back with.
 

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Discussion Starter #5
Thanks again. I started to some of your earlier described tests yesterday. I already found a bad right front signal light assy where the inside spring was rusted in a lower position therefore not making good buttons contact. I have new ones on order. I also checked the volts at the fuse panel and found all but the instrument panel fuse to be about 11.5. The instrument panel fuse had no power to it with the headlights on or off. I assume that I need a new headlight switch. I will verify that power feed tomorrow and order a new one if needed. Grounds are on my list as well. I have many problems it seems.
 

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No problem. I would highly recommend doing both the ground test (and repair if needed) followed by the power feed test, reporting back specific voltage readings as requested.

Until we know those are solid foundations, anything else (including headlight switch replacement) could be a waste of time and effort. Don't build on a shaky foundation.
 

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Horns: test independently. If the horn sounds good off the battery directly, clean the back of the bracket and the radiator support. If that doen't help, then it is check the wiring time.
The lights all have a local ground. Make sure that is clean. The front fenders also need a good connection back to chassis. You can measure the ground with a multimeter on Ohms from the fender to the negative terminal on the battery. Just take one issue at a time.
 
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