QuestionQUESTION: The lights on my car has started coming on sporadically. What sort of problem does this represent? Is this something that should be addressed immediately?
ANSWER: Hi Parke,
The ABS is designed so that if it has a fault nonetheless the car will brake just as well as a car without ABS. So it is not an emergency to get it diagnosed. The traction light usually just means that slippage of one wheel is being dealt with by the traction control system. It is not generally a sign of a problem.
On the ABS intermittency, if it goes on and off during a single trip the most comon reasons are: abnormally high or low operating voltage experienced by the ABS computer, interruption of current to the computer or to the modulator will cause the light to come on and if the current is resumed the light will go off. The last intermittent cause is a failure in the digital communication system, but then the ABS and the Brake warning light will come on and a message will appear in the odometer window "no bus".
The first thing to do would be inspect the plugs and wires of the system. I can tell you the list of possible items and be more specific if I know the year of the car. The most recent manual that I have for the 300M is 1999. If you have that older bodied 300M then that manual is probably recent enough. However if your model has the new body, still in production, then I would be doubtful that my wiring diagrams will be of any help.
So, I would not be overly concerned about driving the car in the current status, but move ahead deliberately along the lines suggested above.
Let me know the year model and what sort of effort you want to put toward checking it out yourself if I can provide the correct specific information.
Roland
PS Use the "thank/rate" tab to send me a 'follow-up question" without having to wait for me to be 'available' to take a question. There is a space for comments.
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QUESTION: The car is a 2000. It has 98K miles on it. Any more info would be greatly appreciated. It has a tune up around 65K. Would another tune be advised?
AnswerHi Parke,
Tune ups (spark plugs/wires is about all) aren't needed that soon. Plugs require changing every 100K miles, so a tune up is not needed.
If you haven't changed the transmission fluid, that would be adviseable according to the maufacturer's tables. Air intake filter element and PCV valve function should be checked for possible need of replacement.
One item that should be evaluated at this point is the timing belt (100k), if your engine is 3.2 or 3.5L (the 2.7L has a timing chain so this is not an issue for that one). Unfortunately there are some accessories and drive belts and the crank pulley that have to be removed just to inspect it (but a lot more than that has to be done to change the timing belt!). I don't know what to recommend to you on this one. The recommendation is to change it, yet I believe if the engine has been not driven hard it probably is fine. The big issue is that with the 3.2/3.5 if the belt breaks then there is damage to the valves/pistons. So you have to compare the price of inspection/replacement/damage if it breaks/budget and decide what to do.
On the ABS there are 4 fuses to check to make sure they are tight and clean in their sockets: 17 and 20 behind the dash, and H and K in the power box in the engine compartment. There is one control unit and its 25-pin plug to inspect for possible poor connection, but I doubt that is the issue causing intermittency, and it is a hassle to get to. Rather take a look at each of the 4 wheel rotation sensors each of which has a wire that might not have a clean/tight electrical connection to the sensor. They are accessed by raising each wheel and removing the tire/wheel and looking at the back side of the brake unit where the sensor is located. You can decide if you want to go through that process at this time or not.
If the ABS light comes on and stays on that means the control unit has identified the problem which then can be dealt with. At that point a code reader attached to a plug under the dash will be used to read out the fault code number which will describe what it thinks is wrong with the ABS system. Until then, if you check the fuses and the individual wheel sensors that is about all I would recommend, or at least the fuses. I even wonder if the cause might be related to a voltage regulation issue more generally rather than anything to do with the ABS system itself, as a dip in voltage of the system (alternator/voltage regualation) evidentally will cause the ABS light to illuminate as well.
Roland
PS Thanks for the kind remarks and nomination
