QuestionQUESTION: Dear Hyundai Expect:
I am the original owner of a 2001 Hyundai Santa Fe with approximately 140k miles. I have gone through three batteries in four years. The positive charge on my battery gets a lot of corrosion build-up during the winter. Recently, the problem has been the "check engine light".
The check engine light has been turning off and on since the beginning of the spring. I have noticed that it stays off when it is not hot outside (I live in AL and it gets pretty hot during the summer). When the light cuts on, it sounds like my transmission. Once the car makes an adjustment (a crazy jerking/clunking sound), it drives fine. It loves the highway and purrs like a kitten. The light tends to come on in stop and go traffic in the city. It cuts on around 70mph on the highway, but less frequently than city driving. Sometimes when the light cuts on, the engine roars and will not change gears. I had the transmission checked by a transmission expert and it was fine. My mechanic thought it was the transmission, too! Sometimes the light cuts on without a lot of fanfare.
My mechanic took apart the alternator because the car was running sluggish when the check engine light was on (windows moving slowly and dim lights); however, the alternator was fine. Also, once I replaced the battery, everything was fine (except for the check engine light).
I am not a driver that ignores a check engine light, so this warning light is driving me and my mechanic nuts! My mechanic is baffled and so am I. I do not know what to do. Whatever it is, it is not showing up on the computer, but is giving all sorts of crazy codes to my mechanic.
I am starting to think the problem it is electrical. I am a graduate student and cannot afford a new car. I am worried - big time! I appreciate your opinion.
G:(
ANSWER: Hi, Gina. Unless there's been something lost in the translation, I'm thinking the mechanic looking at your vehicle may not be the best mechanic to choose for diagnostic type work. For example, I've never known it to be necessary to take an alternator apart to check it, because the parts to rebuild alternators are no longer readily available in small quantities. Once we know that the alternator is receiving proper input and is not providing proper output, we know that the alternator needs to be replaced.
Based on your description, the problem indeed sounds like it's related to the transmission. My guess is that your mechanic's diagnostic tool does not communicate with the transmission control module, and thus does not retrieve the trouble codes contained within. In most cases, the cause of the symptoms you describe is an faulty input or output speed sensor, fairly simple components of the transmission to replace; they bolt directly into the transmission case. The potential is still there, though, that this could be a more major issue. If you do not know of a shop nearby with equipment that can read both your engine and transmission diagnostic trouble codes, I'd recommend taking the vehicle to the local dealer and have them diagnose it. With luck, it'll be a simple repair and you'll be driving again without lightening your pocketbook too much.
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QUESTION: Thanks for your quick response. My mechanic thought the problem was my transmission. So I took my car to the transmission expert here in town. I was told that it was not my transmission. The transmission mechanic wrote down the codes and also test drove the car and nothing happened. I will take my car back to the transmission mechanic one more time. What about the hot/cold sensitivity? Is there a heat sensor or thermostat that could have gone bad? Also, I used to service my car at the local dealer; however, I encountered problems with the service and repairs.
G:(
AnswerIf the transmission expert couldn't tell you anything more than the trouble codes and that the problem isn't in the transmission, then he's not the person to be repairing this. Do you know the trouble codes he wrote down?
It's unlikely this is related to the thermostat, as that would cause abnormal engine temperatures. Many electrical components fail at certain temperatures due to expansion/contraction.
If you've had troubles at the dealer, you could go to an independent shop good at diagnostics and with the tooling necessary to communicate with both the engine and transmission control modules (both data and trouble codes). Without this tooling, anyone will have trouble diagnosing and repairing your vehicle. I originally recommended the dealer because they'd be sure to have the appropriate tools. Alternately, if there's a different dealer close by, you could try them.
