QuestionQUESTION: Hi - my 1979 MG midget has some lights that don't work and I am completely frustrated. Left rear light, blinker, flasher and side ligth all work, right rear light, license light and marker don't work. Here is the frustrating part, the right brake light, and flasher do work - I can't figure it out. Any ideas? I am an aature at this stuff have soem testing equipment but don't know how to go about using it.
ANSWER: Hi Tony,
The only tools you need is a wiring diagram and a 12v test light.
The diagram tells you the color code of which wire you need to check with your test light back at the tail light assembly. Don't forget to test grounds also.
Always pick ONLY ONE item (circuit) to test at a time and when you have corrected that item go to a second if there is another. Many times that one circuit will correct the others.
NEVER try to guess what is wrong. ALWAYS test to find the problem.
I like to start at the load (item that don't work)and test each joint on the way back to the power supply. Some mechanics go the other way.
If you don't have a wiring diagram, let me know and I will put one up on my web site for you to copy.
Howard
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QUESTION: when I said I was an amateur..I meant it. i do not even knew how to test with a test light. I am a quick learner but need an overview. I read to test for circuit problems to take the need terminal off the battery, put the alligator clip on the wired side and the probe on the terminal side and it should light up if there is a fault. How does this equate to the wires and the light sockets and the grounds?
AnswerThe test you read somewhere of removing a battery cable and putting a test light between the cable end and the battery post is a test for something running a battery down when parked. That has nothing to do with what you asked me about.
If you have a test light you know that it has a clip on a wire and a pointed probe. When testing for power you connect the clip on a clean ground like a clean nut or head of a bolt but it must not be painted, you need the clip on bare metal. Then use the pointed probe to search for things (wires and items that are powered)
When checking to see if a ground wire is grounded, you connect the clip to a "HOT" wire (powered wire)and probe grounds to see that they are really grounded.
A quick easy exercise is to connect the clip to the ground cable on the battery and probe the power side of the battery and a few places on the fuse box to see how the test light works. Then connect the clip on the power side of the battery and start probing the engine and body parts to see what is grounded.
Howard
