QuestionQUESTION: About a week ago I started my intrepid and backed it out of the garage and turned it off. When I started it again it acted like it was running rough and then killed shortly after. I couldn't start it again. I let it sit overnight and it started easily and ran smooth. I started it yesterday morning after a cold night and it ran rough again but running. After it ran a while it seemed to run smooth again. I ran the diagnostic default codes and it came 12, 66 and 55.
ANSWER: Hi Joyce,
The 55 code means "end of readout". The 12 code means the battery was disconnected recently from the power supply to the computer. Recently means the last 50-100 key cycles. If that is not the case, you may have a poor connection at battery cable clamp.
The 66 code is a late entry in the OBD-I system of codes that was phased out in the mid-90's. In fact, I am surprised you could get the code in your '97 vehicle as by then the switchover to OBD-II had occured which has 4-digit fault code numbers. Was the engine computer in the car exchanged at some point? Did you use the ignition key and check engine light to get these codes?
The 66 code means that one of the 3 computers is acting up (either the engine/transmission/body computer). They are tied together through a digital data communication pair of wires. The rough running points at the engine computer as the cause.
Probably, if this is the original '97 computer, you can get the 4-digit OBD-II codes that are more specific as to which unit is at fault. There is a plug under the dash next to the steering column into which a code reader is plugged. An Autozone parts store will often do the readout for free. An independent garage will do it for about $40. Ask for the specific fault code numbers, what they mean, and what is recommended to do. Write back with the numbers and we'll compare notes and go from there.
Roland
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QUESTION: I went to Autozone and their diagnostic reader came up with "P0306, misfire detected on cylinder 6." He recommeded new spark plugs and a tune up. What do you think.
Thanks
ANSWER: Hi Joyce,
Aha! I am glad that you got a 'second opinion' using the more complete and possibly more accurate OBD-II system.
However, I am not certain that simply replacing the spark plugs (and a 'tune up', which is a very non-descript term and can be an open invitation to go almost anything whether needed or not) will correct a specific cylinder code such as the reader gave. The code means that the rpm of the engine dips slightly just when the #6 cylinder is supposed to fire which suggests that it isn't doing too good a job. I would begin by checking the wires to the spark plug, and if you have the tool replacing/cleaning the spark plug for that #6 cylinder. Also, take a look at all the spark plug wires on a humid evening in the shadows (it needs to be dark in the engine compartment) to view whether you see an arcing occuring along the spark plug wire which would be a sign to change that specific wire because its insulation has deteriorated. If the problem is not severe and your budget is tight I would be inclined to just keep checking for a more specific fault code to show up at a free readout at Autozone and when that happens deal with that code.
Roland
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QUESTION: Ok, I will let you know what happens when the spark plugs are checked out.
Thanks,
AnswerThanks, I'l be interested to learn. If you have the tool or a friend who has the tool and skill to pull the #6 plug then it won't cost anything. Otherwise, just pay to have the plugs changed, but generally plugs last at least 50,000 miles (100,000 is sometimes suggested now days) so if they were replaced in less than that time frame it may be a waste of money to do that again.
Roland
