QuestionQUESTION: hi
after a long trip when i shut off the engine and remove the key some times the oil pressure indicator still illuminate but with very low light, at this time no cranking can be happen and every thing is dead, also one time the tachometer not return to zero after engine shut off jointing the oil indicator very low light, after one minute
the light goes off and i can start the engine.
please help,,
ANSWER: Hi Essam,
It may be an issue with the digital communications between the engine controller and the instrument cluster but the best way to find out would be to do a self-diagnostic using the ignition switch: turn it "on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. Then watch the instrument cluster to see the mileage reading to be replaced by a 4-digit number preceded by a P. Let me know and we'll go from there. Also, tell me what exactly is 'dead' and what still works, the next time this happens. If it is truly 'everything', then I would suspect the issue is related to the battery connections or to the ignition switch. But let me know the results of the self-diagnosis.
I just found your question in the 'pool' to which it had been referred by the other 'expert', Kevin.
Please 'rate' my answer (see the PS below).
Thanks,
Roland
---------- FOLLOW-UP ----------
QUESTION: Hi Roland
I'm glad that you are responding me, you helped me many times,
No fault code was found it writes DONE when the self diagnosis is applied
In the problem presence I loose the cranking and when I remove the ignition key my seat don't return back (seat memory), except that every things are working including the head lighting meaning the battery connection is ok,
Look, the digital communication is passing from engine controller to body controller then to instrument cluster, now this digital is disturbed in somewhere between them, or one of them have intermitted short or power leak internally ,
Now, let us analyze :I just replaced and program the engine controller with a brand new one, knowing that the problem was existing with the old one, the deference that the problem could be happen through driving causing engine shut off, but now it happen only after long trip in hot weather when I shut off the engine, let us go to body controller it collects all digitals from all other controllers and organize, since every accessories is working ( except the memory seat) I discard the body controller,
The instrument cluster module is controlling all indicators electronically except the oil pressure lamp, it just feeds this lamp with ignition power through a direct connection when it receive the power from the ignition key,(as wiring diagram) meaning this lamp must goes off when the key is turned to off, but it still receives some very low voltage, now since the instrument module is supplied with battery power permanently, I expect there is a power short inside the instrument module causing return some power to engine controller through the digital bass disturbing it, some power to oil lamp , some power to tachometer eliminate it to return to zero after shut off the ignition ,
If you agree with me I will remove the cluster, may be some dirt, also I have a used instrument cluster and used body controller. You opinion is very important and respected for me.
Thank you
AnswerHi Essam,
I am not certain that the issue is in the digital communication system or the cluster, but it could be either. However, it may be in the ignition switch or its wirings or the starter motor circuit itself. So you might start by listening for the starter relay to click or not (you may need a helper to operate the switch). If not then be sure that the starter section of the switch is powering up when this malfunction occurs. Pin 9 of the ignition switch is what powers up the starter circuit when you move the key to the start position. Then if those check out I would also try a direct jump to the starter solenoid switch to test whether the starter motor itself may be the problem when it is heated up after a long drive.
Also, on the memory seat, it may not be returning because fuse 14 in the dash is continuing to be powered after you turn off the key (which would explain its failure to retract).
On the oil light, that is not apparently controlled by the communication system at all but rather the warning lamp is shown to simply ground the bulb when the pressure drops too low (but here is the problem: the circuit shows the bulb to be powered even when the ignition is off (A81,F11), so I don't understand were that the case why the bulb wouldn't be 'on' all the time when the engine wasn't running!) Take a look at the cluster wiring diagram and let me know if you understand the oil pressure warning lamp circuit.
But of course if you have used cluster and bcm try those. I would not recommend buying replacements however until you check the ignition switch circuitry further.
I follow your logic and applaud your analysis, it is just that I am not certain that the digital communications in and of themselves can explain this fully.
Please 'rate' my answer, click 'yes' for a nomination (see the PS below).
Thanks,
Roland
