Hi,

My 92 Eldorado has an unpredictable electrical gremlin.

Sometimes my brake lights won't work, and at the same time this is happening, the fuel door switch won't open the door (my luck is of course that the emergency cable wouldn't work either....but that is a mechanical problem and unrelated I believe), and the cruise won't work.

With the gremlin, if I have an indicator on, and press the brake pedal, the indicator will "freeze" until the pedal is released. The only other thing I notice is that the parking lights are on dim to moderate and the third brake light is also lit at about the same intensity.

The problem comes and goes, and I've replaced ALL the bulbs and checked the sockets, including the small (1094) bulbs, fuses, as well as the third brake bulbs, without any improvement. When the problem isn't there, all lamps, fuel door, and cruise work correctly. This is extremely annoying and not too safe as well. I'v heard the brake input switch or some such by the pedal goes bad, but I can't understand how I'd get an intermittent problem out of it if it was bad. I hate to spend $$ for a switch if there is something relatively simple someone is familiar with that is common with the breed.

Thanks,

John

Gremlin is an understatement John! Despite being an annoying inconvenience, your intermittent brake light operation is a major safety issue. Do you have a GM shop manual? If not, I'd recommend getting one ASAP. For less than two hours of shop labor, you'll have the "paper brains" that can save you loads of time (and hard-earned money) when troubleshooting these types of problems. Even if you don't understand everything in it, you probably have a friend that can. So by all means, buy a manual and save yourself a lot of grief. Besides, you can always read it on those nights when you can't sleep! Alright, let's move on.

This sounds a lot like an intermittent ground fault, but one must always keep an open mind when troubleshooting intermittents. What you need to do is obtain a wiring diagram and determine what wire(s) is/are common to all the circuits affected. You list three. Have you checked the operation of every electrical device? If not, do this first.

The shop manual will also show you the path these harnesses (or harni --plural, in geekspeak) take. If there is any wiring that is routed near chaffing or "pressure" points, (the column, etc) you could have a damaged wire (nicked insulation, cut wire joined by just a few strands) or intermittently contacting connector pins. Intimidated? Don't be. Like failed relationships, the majority of electrical problems are really simple to understand --once they're over. Do get a manual, but in the meantime there are still things you can do. And where there's a plan, you still have hope.

Think back to when you first discovered the problem. Had you been working on the car? Did an ashtray full of pennies spill all over the place? If the answer is no, then look for mechanical reasons for the fault (discussed above). Get a really bright source of light and slooooowly follow as much wiring in the affected areas as possible. Trunk hinges that could be wearing through a harness, a brakelight wire hanging by a thread, that sort of thing. Where a wire goes into a harness, give it a little tug to make sure it's mechanically intact on it's pin or contact. Don't reef on it or you'll just generate new problems. Open up any applicable connectors and inspect for corrosion which can lead to intermittent contact. If you can safely get into the steering column, (cruise control circuit) check those wires too. When you get moving objects (steering wheel) and wires together, sometimes bad things happen. Do this methodically; write the results down and keep repeating the electrical Gremlin detection mantra, "If I haven't found the problem, I'm not looking in the right spot yet." Effective electrical troubleshooting is an art and a science, but sometimes. . . it really comes down to just plain, dumb luck. Write back with any results and I'll help if I can. Also, what is your troubleshooting experience level? (It pays to know your audience.)

CC