| am gasit pe ceva forumuri de nissan si m-am gandit sa il pun si aici...se zice ca merge la orice primer a p12...eu inca nu am reusit biggrin.gif poate aveti voi mai mult noroc
Recently, my 3.5's Check Engine Light (the FSM/ESM term is Malfunction Indicator Light, or MIL) illuminated in all its amber glory. The light presented with it no other symptoms, so I finished what I was doing that day, came home and threw myself into the ESM, which is rather less interesting than reading the dictionary, only more prone to put you to sleep.
The local network of wiring, sensors, controllers, chips and other various bits of silicon in the Altima is apparently vastly complicated, so I won't bore you (or me) by addressing it in detail here. However, one thing I found interesting is that the MIL shines only under two conditions:
1) If the ECM detects what Nissan considers a "serious" fault (such as a misfire), the MIL illuminates immediately and the ECM stores a trouble code. 2) If, however, the ECM senses a less serious problem, such as a vacuum leak, the MIL does not illuminate immediately. Instead, the ECM stores an identifying trouble code and waits to see if the same fault arises during the next trip cycle, which roughly corresponds to the next time you hop in the car and drive it around after turning it off. If the ECM senses the same fault, it trips the MIL light and you get to wade into the ECM or make the always-entertaining trip to your local dealer.
Your dealer uses a scan tool called a Consult to interface with the ECM directly. However, shadetree mechanics can manually pull the trouble code(s) from the ECM and, if desired, clear the code from memory, thus putting out the Check Engine Light, which incidentally shines like the fires of Hades at night against the dimmed gauge cluster.
To check the fault code yourself from the comfort of your own garage, put the ECM in "Diagnostic Test Mode II" by doing the following:
1) Sit your butt in the driver's seat. 2) Turn the ignition key to the ON position and wait three seconds. (Do not start the car.) 3) Fully depress and release the accelerator pedal five times in less than five seconds. (If you've got bad ankles, give up now and drive the car to the dealer.) 4) Wait exactly seven seconds. Fully depress the accelerator pedal and hold it down for about ten seconds until the MIL light begins flashing. 5) Release the accelerator pedal and start counting flashes to obtain the four-digit trouble code. Long flashes (0.6 seconds) indicate the first digit of the code; count the blinks one through nine and write down the first digit. (Ten blinks indicates a zero.) The next three digits follow in turn in the same fashion except with faster blinks (0.3 second) and a 1.0-second pause between digits.
The ECM code repeats intself until you turn the ignition key to the OFF position, at which point the ECM resets itself to standard get-in-and-drive-the-car mode. You can look up the trouble codes in the ESM/FSM; there's a bunch of them. In the ESM, refer to page EC-639. Additionally, if you get four blinks of ten (0000), the ECM is indicating no malfunction.
You can clear the code (and the annoying MIL) by holding down the accelerator pedal for more than 10 seconds while in Diagnostic Test Mode II. When you release the pedal, the ECM erases the trouble code(s).
In my case, my trouble code was 0442 - "Evaporative System Small Leak" - discussed on page EC-973. This could indicate anything from a poorly sealed gas gap to a leak in the evaporative recovery system underneath the car. I checked everything I could and decided to clear the code, thinking that maybe a slightly loose gas cap might've been the culprit. It apparently was, as the MIL hasn't shined since. |