ams@hou4b.UUCP (08/10/84)
Some time ago I had an interesting experience in my 1981 Pontiac T-1000 (same car as Chevy Chevette): I was driving along and the "check engine" light (not the same as the "oil" light) came on. The manual said is was a problem with the "Computer Command Control" (seriously) and/or the oxygen sensor in the exhaust system. This was accompanied by major stalling at toll booths. By the end of the trip the stalling had gone away and the car was wanting to race across the parking lot at 45mph without any foot on the gas. So I took it to the shop where the fixed a perviously undiagnosed exhaust system leak and turned down the idle. Driving to work the next day, the light came back. I was told that the automated diagonstic routines could find nothing wrong and I should wait until something broke, whereupon they could fix it. Currently the light comes on after about 5 minutes of 60mph or above driving, stays on for 5-10 minutes, and then goes off again. The cycle then continues with variable intervals. The cycle does seem to have something to do with speed, since I have never seen it come on below 55 and it always goes off when I get off the highway. However, it also goes off spontaneously if I just ignore it and keep going 65. Gas mileage is still about the same as it used to be. Does anybody have any idea what the problem is? This has been going on for 3 weeks now, and nothing else has happened. However, I am still paranoid that something will break, leaving me stranded in the middle of the night on some deserted stretch of road. Thanks for your help, Andrew Shaw AT&TISL 834-4085 HO 1C-412A houx[a-z]!hou4b!ams
rls@iham1.UUCP (Rick Schieve) (08/10/84)
The check engine light on late model GM cars does not really qualify is an idiot light as most people think of them. It does not monitor a specific engine function, but rather it lets the driver know that the computer control thinks something is wrong. The computer has multiple inputs such as engine temp, barometric pressure and even a sensor in the exhaust. It in turn controls gas flow, spark advance, etc... Any time the check engine light comes on while driving, it is an indication that the computer is not happy with something and if it is not happy ist can screw up the car in many ways. The fact that the light came on tells no specifics. THowever, as long as power is not lost to the computer, it remembers what it was complaining about. Its memory can be dumped by shorting two terminals together at the diagnostic jack under your dash. The check engine light will actually flash an error code indicating its specific problem. Buy or borrow a service manual. The specific procedure along with diagnostic flow charts will probably pin point your problem. I was skepticle myself until my wife's 81 Camaro had some problems and after reading the error code the service manual pointed right to the faulty computer temperature sensor (which is not the same as the sensor that runs gauges or idiot lights). Rick Schieve
mikey@trsvax.UUCP (08/13/84)
#R:iham1:-18100:trsvax:55200098:000:731 trsvax!mikey Aug 13 09:05:00 1984 On GM computers you have to jumper the computer BEFORE the problem occurs to tell it to remember the problem. If you don't, it will only remember until the first time you shut off the ignition. Then once the problem happens, you strobe one of the input pins on the computer and it will flash a code on the dash indicator light as to what it thought the problem was. If you leave the jumper in the "Remember" position for extended periods without running the car, it will run the battery down. This is why it is not left on and you have to jumper it. According to my '80 Phoenix shop manual, if you run your car every couple days, you shouldn't run the battery down too far, but it depends on your car. mikey at trsvax
berry@zinfandel.UUCP (Berry Kercheval) (08/13/84)
This may or may not help, but I had an idiot light problem on my '84 VW Jetta after about 2 months. The 'fasten seatbelt' light would come on at random intervals, stay on for exactly fifteen seconds and then go out. The dealer fixed it under warranty by replacing a faulty relay. The moral of the story is, idiot light problems may be a fault with the light itself (and the associated circuitry) and not the engine. BUT CHECK 'EM BOTH! When I used to work on process control equipment, we always put in circuits and software (sounds like a RPG: "Circuits and Software" But I digress) to test the indicator lights and meters. But in a car? Noooooo. -- Berry Kercheval Zehntel Inc. (ihnp4!zehntel!zinfandel!berry) (415)932-6900
tbul@trsvax.UUCP (08/13/84)
#R:hou4b:-108700:trsvax:55200099:000:737
trsvax!tbul Aug 13 12:14:00 1984
I had a similar problem with my '82 Firebird. It was only a few months old
and the check engine light came on. I took it back to the dealer and they
pulled a little knob (unfortunately, I forget where) and the light flashed
a code. The code said that the oxygen sensor was bad along with another part
(could have been the computer...). When replaced, I haven't had the problem
since.
I would suggest that you sneak into an auto parts store or local library
and look up the section regarding the light. There is probably some switch
that you too can pull and get an answer to your problem (albeit the light
will probably have to be 'on' (indicating a fault) at the time).
Hope this helps,
Tom Bulkowskilambert@vax4.DEC (08/15/84)
>><<
Sorry if this is redundant, but I've missed a few articles in the past
couple of days.
The oil pressure light in my GTI has been coming on for a couple of
weeks now, accompanied by it's incredibly nasty buzzer when above 2000 rpm.
The problem only happens when it's humid or wet outside, and only lasts
until the engine warms up. There's no valve clatter or other noise to
indicate a real problem, though at times it seems the oil temperature is a
couple of degrees higher than normal. (That may be due to the fact that I
normally don't pay much attention to the oil temp, and don't know what
"normal" fluctuation might be.....)
The dealer checked all the pressures, etc. and said they were fine (of
course). Is this similar to your problem? If not, has anyone out there
had trouble like this? Any recommendations?
Mucho thanks,
-- Sam Lambert
rhea!decwrl!vax4!lambert
<<Nothing is foolproof if the fool is dedicated enough>>