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Do you have Start Error message in the Instrument cluster? are the radio and blower operational with ignition on?
The reason for asking this is because the immobliser system recieves ignition 12v from the same fuse as blower and radio. So the fuse is definately in order. No start error message indicates that immobiliser should work fine.
If engine does not start in this case that might mean that engine control unit does not recieve ignition signal. If the glow plugs do not activate when ignition on, that would be a confirmation. Unfortunately i do not have the relay positions at the moment to provide you. i will have this info in 12 hours. If you feel that my answer is unsatisfactory at the moment, you have the option to opt me out and not to accept my answer, so that other experts could assist you.
I will be back online in about 12 hours, then i would be able to give more info.
Hope for you understanding,
If there would be a problem with glow plugs, the glow plug relay light would be on after an engine start. THe longer start is probably due to one of the injectors leaking too much fuel into return line.
Could you provide me with a VIN of your car, i need to find vehicle-specific diagrams to find the solution.
If you got the right pin, there is no voltage when ignition off.
Older Sprinter models indicated immobiliser failures by glowplug light. Your Sprinter should indicate it by start error message. Since there is no message i assume that no fault on drive authorization. So if the ignition is on and starter shorted, engine should fire. Since it does not, ECU does not see the ignition on. One more thing to check would be the voltage supply of it. Would the engine control unit wiring diagram be useful for you?
In my experience, the problems causing failure to start were fuses, immobilizer ,engine control units or ignition keys needed to be reprogrammed.
For one reason or the other my explanation for opting out did not go through. I am sorry for this.
I opted out because the only step i see is to diagnose the malfunction with Star Diagnosis scantool. The memory of the immobiliser can be lost by disconnecting the battery. It is absolutely not normal but possible.
Maybe other experts have more knowledge on this malfunction, or the solution without using diagnostic equipment. I will keep my eyes and ears open for possible solution, and if i will get it- i will reply to you immidiately.
Please reply to this post for other experts to see it.
Hope for your understanding,