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Discussion Starter #1
My friend is having 2 problems, and I'm no help, know nothing about electrics, can't understand wiring diagrams, he's not a member yet, he just bought a 68 xr7, and is starting to restore it.

He says he checked all of the wiring in the car with a test light, pulled the harness, tested each wire, and had a light showing power went thru to the other end. Now has installed it all back, has taillight, headlight, dash lights, but no courtsey lights, either by opening the door, or by turning on by light switch, no wipers, (told him it might the switch), no front marker lights, and no power to overhead console.

Second problem is the alternator diagram shows a 4 wire connection, and his only has a 3 wire, and the stator is hot all of the time.

I know this a lot, thank you in advance
 

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Checking everything with a test light doesn't tell us much....has he been comparing it to a diagram in order to know what is hot and what is ground, etc? First I would check the obvious plug not connected, fuse missing, etc. Some of those are on totally different circuits, so it would be beneficial to just pick one and start tracing it out. Say the wipers for instance - follow a diagram it shows you what color/markings go to which connector/pin all the way from the 12V source to the switch, and to the motor. Some may look a bit perplexing like the wipers since they have multiple speeds, but ultimately you just need to verify that there is voltage along the path until you find a place where voltage is lacking. First of course you check the fuse for the circuit, if it's good start tracing the path. If its bad see if it blows right away when you swap it (something is shorted if so). then youstart disconnecting plugs/wires in it's path to issolate the short and you can begin testing with an ohmeter on individual wires to ground to find the short. It's easier to watch a video than try to explain it....try googling youtube videos for finding short circuits. I bet theres a bunch. One thing to keep in mind is that they used the same wiring harness in different models, so be sure you are looking at the wiring that is relevant to the model. EX - a standard does not have all the bells and whistles an XR7 does so it may have more "dead ends" that do not apply....

DC circuits are pretty simple - they have to have a source (+ 12V) and a return path (- ground) which is typically the car body/frame/or wire that is grouped to others that go to the battery neg/frame/body conection. It's a matter of knowing which wires are what - via the diagram.

Not an exacting answer, but not an exacting question.....just a direction to to head.
 

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Discussion Starter #4
Well all I know is that I helped him with this "test" light, some cheap thing bought at an auto store that has a metal point on one end, and an aligator clip on the other, with a light on the metal tip end. If for instance we took an orange w/black stripe wire, we attached the clip and where the wire came out of the harness on the other end, touched it with the metal point, if the light came on, we thought that meant that the wire was good, no breakes or shorts.

Did that for each and every wire, so assumed that if power went thru, once installed, all should be OK.

Changed all of the fuses in the block, fuses are not blowing,,,, are there any in line fuses?

What would control the interior lights, is the dominating factor the door jamb switches, perhaps one is bad.

If fuses are not blowing, then there isn't a short??
 

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On my 69 there is a ground wire at each end of the dash. I don't know if the 68 is set up the same way (possible though). If these grounds are not connected to the car's structure the courtesy lights will not function. I found this out the hard way.....
 

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^^ Good point. It sounds like the perverbial bad ground/return then. The test light just lets you know there is power to that point, it still needs to have a good return path either via the socket or another wire. If you find wires that are not "hot" then you may be looking at a ground wire. You can test it easy enough by putting the clip end on a known good hot wire and touch it to the unknown/dead wire. It should light if it's a ground, otherwise it may be a dead end for an option your car doesn't have or it's an open/broken wire....If the dash is not grounded then it will need to be. Not sure on '68 either..? Easy enough to test by touchig the test light to a known good source and then seeing if it will light when you touch various metal points in the dash. Sounds like you don't have any shorts - so you got that going for you!

Another thing, there needs to be a good body to engine ground under the hood. The factory one sucks - just make yourself one out of nice heavy guage wire and pick a nice clean spot on the body/frame. That will elliminate future ground gremlins.
 

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Go to radio shack and get an analog multimeter and use the ohm function to test for ground.
 
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