QuestionAnother question regarding my 77 MGB. When I start my car, ( not all the time ), sometimes I hear the relay click, but the starter will not run. After a few tries, it will start. It always starts, just don't want to be out and about, when it decides not to. Do you think it's the starter? The ignition switch was replaced some time ago, and I don't think that is the problem since the fuel punp, and the relay work when I turn the key. Thank you for all your help in the past. Bob .
AnswerHi Bob,
The intermittent electrical problem to any mechanic has always been a problem because you have to have it in the failed mode to test and track down the problem.
You have three main areas in the starter system to look at first are, the starter, starter solenoid and the solenoid relay. Each needs to be monitored at the time of failure. It could still be outside of those in the battery cables, grounds etc.
I was faced with this type of problem hundreds of times in dealerships I worked in. It is like telling a doctor "My arm use to hurt but don't hurt any more, what was wrong with it?"
The point is you need to do the tests when it fails. As a line mechanic I had this happen too many times and especially on electronic fuel injection cars like the Jags. I went to Radio Shack and purchased several LEDs and installed them in a small box. I wired three up as grounds and four as powers. I then connected wires to all the points I knew had to be monitored and set the box on the dash and drove the car until I had the intermittent failure. By looking at all the LEDs I then spotted the failed item and replaced or repaired that one failing item.
You may never have another intermittent failure in your lifetime so you don't need to go to that extent. However, you may need to run several wires to critical test points and put LEDs or 12v bulbs on the few wires you need to monitor. Or you can use one test light and move it around to each point after you test each item.
The first test is the starter itself. Connect the test light to the large post on the starter and watch for a light when it just "Clicks". If you get a light when it just clicks you have either a starter problem or a battery cable or ground cable problem. If no light then go to the solenoid "Small" trigger wire (white w/brown tracer)Do the same test. If you don't get a light go back the the relay. Output on the relay is post "C-2".
Other than tossing money at the problem this is the only way I know of testing for an intermittent problem.
Let me know,
Howard
