I've got a '90 Ciera S that, to my astonishment, was sitting in my mother's garage when I opened it after going to her home following her death. What happened to the much nicer, new Mercury I'm still trying to figure out. But, in any case, after putting several hundred into it so I could use it to get my tools home to California (after fixing-up her house), I've been driving it because I'm by-god gonna' get my money back out of it!
At any rate, it has started doing something really odd, and only intermittently... and it's possibly heat-related (only I'm still trying to figure that out).
Basically, it runs fine most of the time. But sometimes, after I start it and pull out onto the street, the tachometer suddenly starts jumping all over the place; and all other dials go up or down (usually down); and the radio and other dash light dim; and all the dials and tach and speedo needles and gas guage and alternator guage and temp and oil pressure, etc., all kinda' bounce around like there's some kind of short (though it doesn't seem related to bumps in the road or anything like that)... especially the tach... it just goes wild. Sometimes it affects the engine, which starts to kinda' run unsmoothly, and sometimes it doesn't.
When it happens while I'm driving or sitting behind a car at a stop light, I notice the even the headlights (shining on the car in front of me) dim, then brighten, then dim, erratically... along with all the other stuff going nuts.
I took it to the mechanic and he said it happened while he had it (though it took a while) and while it was happening, he tested the alternator and said it was providing steady current... no voltage regulator problems, he thought. He said it sounded like something was clicking in the dash, but he said that could have been a symptom, not the cause... and he based that on the fact that the cruise control unit was clicking, too whenever it was happening. He said it was likely some nutty, intermittent electrical problem... probably in the dash... and he just didn't want to tackle it.
While he had the car, I had a thought: What if the vibration from the crappy tires (before I replaced them) had jiggled a fuse loose or something. So when I picked-up the car from the mechanic, before I started it up, I made sure all fuses were seated. And it started right up and didn't do it. But then again, it was the cool of the early evening, so who knows if it was that, or my reseating the fuses.
I'll say this much, though: I then drove it without a problem for weeks... relatively cool weeks, though, I've realized upon thinking back on them... although that may not really have anything to do with it.
At any rate, the other day, while sitting in traffic on a terribly hot day, it started doing it again. I drove straight home and parked the car and decided to check it after the cool of the evening set in.... but I forgot to do that.
So, today, I went out (very hot again) and tried again and, sure enough, needles bouncing all over, dash lights brightening/dimming, and this time, the engine not really wanting to stay running. I reseated the fuses to no avail.
So, now, as I write this, the precise symptom is: Will start (but with a tiny bit of difficulty... good cranking, though); but won't really stay running for more than a few seconds at a time; suns kinda' rough when it *is* running; radio and other dash lights flicker bright/dim (in no particular pattern) the entire time it's running; tachometer jumping all over the place; all other needles more or less dropping down, then up, along with the dash light brightening/dimming; and until I slid the cruise control switch to off, I could hear the cruise unit clicking along with all the other stuff. As it's doing all this, I can also hear relays clicking under the dash, but I think that's basically the same thing as the cruise control clicking: A symptom, not the problem.
If it behaves as it has in the past, I may very well be able to go out to the car this evening, after things have cooled off, and the darned thing will start right up and run smoothly without a symptom. I might even be able to drive it for days or weeks thereafter with nothing.
Has anyone ever seen anything like this?
Should I be looking for something behind the fuse box?
Could the voltage regulator be bad?
Is there some kind of master relay that could be causing this?
Thoughts, anyone?
I look forward to your replies.
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HarpGuy