Bon, toujours dans mes travaux d'OBD, j'ai relevé les codes d'erreurs ECU... et j'en ai un !
J'ai un code d'erreur 19, qui correspond à
RPM signal (crankshaft sensor) -> Incorrect signal
voir cette excellent site :
http://www.topbuzz1.carenthusiasts.co.u ... _codes.htm
"A Crankshaft Sensor (also known as a Crankshaft Angle Sensor - or CAS for short) watch's the position of the camshaft and its relationship with the piston position inside the engine. The CAS is an inductive signal generator, it measure reluctance. The CAS is typicality found on injection engines, and its an important sensor. Without it, the engine will not run at its optimum, and if faulty, the ECU warning light shall illuminate on the dash"
D'après ce que je comprends, l'ECU s'en sert pour calculer les RPM, savoir le PMH (point mort haut)...etc.
"How do I know if a CAS has malfunctioned?
As previously explained, the CAS is vital for the performance of the engine. It supplies a signal back to the ECU so it can calculate ignition timing and the correct fuelling. If the CAS is sending back incorrect data, the performance of the engine decreases significantly, even stop it from working.
However, to overcome this problem, the EMU can use a data map within its memory (which was set by the manufactures) which use some default values to regain correct fuelling and ignition.
But because this data is static and not true live data coming from a CAS, the performance isn't at its optimum. What this means is that the car may feel sluggish, but the car will still work. Also the ECU warning light will be illuminated on dash."
Je suis donc sensé tourner en mode dégradé... ???
Pourtant, je n'ai aucun voyant rouge allumé, la voiture fonctionne plutôt bien, ras niveau moteur quoi !
Donc tjs sur le même site, je suis allé voir ici :
http://www.topbuzz1.carenthusiasts.co.u ... sensor.htm
Il explique comment le tester...
1) premier test
"Is there any way of testing a CAS to see if its faulty?
Yes there several methods, but all involve electronic measuring equipment. If the ECU warning light is on, read the ECU fault codes off with a paper clip to see if the CAS has logged a fault (Note: if the engine is NOT running when reading the codes, then the ECU may log this as a fault straight away because its not getting a valid signal back - ignore this logged fault). Alternatively, use a TECH1 reader to obtain the logged fault codes.
If the CAS is likely to be faulty as this point, do the simple checks as listed below:-
* Locate the CAS and look at its plug for any damage, corroded pins or bad connections etc.
* Inspect the cable form for the CAS and look for any brakes, cuts or splits on the surface. The CAS cable usually incorporates a 'shield' which protects the signal from picking up stray electronic noise from the harsh environment of the engine bay.
* Remove the CAS from the engine and inspect the condition if its 'tip' at the point it measures. It should have no damage or be corroded in anyway."
2) deuxième test
"If the above are OK, then it is possible to check the resistance of the sensor (Figure 9). However, the value depends heavily on what type of engine it is fitted to, i.e. there isn't a standard resistance value for all CAS sensors unfortunately. Also measuring the resistance isn't a compressive way of testing a CAS sensor, even if you do get a resistance value back, it doesn't mean that the CAS is capable of producing a acceptable signal for the ECU.
* Disconnect the CAS connector and with a DMM (Digital Multi-Meter) set to measure ohms (resistance) connect the two probes to the CAS unit. Note: some CAS have 3 pins, this is likely to be the 'shield' connection, ignore this pin for now.
* If the DMM measures 0 ohms then the CAS is likely to be at fault.
* The CAS resistance could measure anywhere between 500 ohm and 1500 ohms (depending on type).
* Locate the 'shield' pin on the CAS (if applicable) and the EMU equilvant pin on its multi-plug. Measure the resistance of the shield wire. It should be a short circuit (i.e.< 5 ohms). If its open circuit (infinity resistance) then there is a break in the shield wire. This could mean that the CAS signal being sent was picking up other electronic signals in the engine bay and changing the signal characteristics, hence upsetting the fuelling and ignition timing. Repair the cable."
3) troisième test
"It is possible to see if the CAS is producing a AC signal by using the AC volt function on the DMM (Figure 10). However, this will show the AC RMS (Root Mean Square) which means that it sees the average AC voltage source being produced. This method will not show if the sinewave is regular or correct, it just means the CAS is producing a AC waveform to the EMU.
* Disconnect the plug to the CAS unit. Set the DMM to measure AC volts. Connect the DMM probes across the two pins of the CAS unit. If a third pin is present, this is most likely to be the 'shield' pin, ignore this for the time being.
* With the DMM secured in position, crank the engine over on the starter motor (starting the engine is unnecessary, but will be difficult as the CAS is unplugged).
* Note the AC voltage measured. A minimum of 0.7v should have been read back. But some sensors may produce a high voltage or up to 1.4v."
J'ai fait les deux premiers tests,
- le cable semble être en bon état
- j'ai trouvé entre deux pins (il y en a 3), 500ohm, donc ça paraît normal...
- je n'ai pas fait ce qui est souligné sur le deuxième test -> faudrait que je démonte l'ECU et que je trouve la pin qui correspond à la "pin shield"...
je ferais le 3ième test après demain....
pour ce dernier test, je ne comprends pas bien, je suis sensé
- mettre le contact sans démarrer le moteur et
- mesurer le signal carré avec un voltmètre, enfin les min/max quoi !
c'est ça ?
avez vous des idées ?
problème de parasitage ? CAS mort ? (je ne pense pas)
problème de cablage avec l'ECU alors ?
qq connait le pb ?
Vivement que je termine mon OBD tools....
merci
m'inquiète moi pour catapat....
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