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Hi, I bought No start car(Ford Mondeo 2.0tdci 2011) so that i can learn about car electronic systems. Im working on it for few months and always find new lead. Now its different, I dont have any clue where to go next. The car cranks but cant start, no comm with pcm and when PCM is awake, the main relay is on(obviously) but, things which are after this relay(dpf glowplug relay,cooling fan motor, and something more which i cant identify but can hear it clicking) are always clicking on and off. This cycle neverending cycle starts when pcm is awoken and ends when pcm goes sleep.One of the DTCs on BCM was: DTC B10E5 wake up signal circuit opened or shorted to power. So I tried to test the wake up signal that goes from BCM(body control module) to PCM and steady 12V is there. Hovewer i found out when this signal is missing and ignition is on I can communicate with PCM( There were no DTCs) also 5v reference was there, but still could not start. Now i dont know where to go next. Could be the wake up signal shorted internally? Or the BCM thinks that it is opened circiut because of always turning on and off. Did you guys had any experience with on and off circuits? The thing is previous owner did replace the PCM and nothing changed, thats why he sold it. PCM grounds powers are good, 5v refference is there also can bus is good. If you have any suggestions please let me know, everything could help. Thanks.
So, you are saying that when the BCM does not send the wake up signal to the PCM, you can communicate?
The wake up signal is needed for communication.
If the wake up signal shorted to voltage, I don't see how the PCM would be awake as it needs the wake up signal for communication. Did you cut the wake up signal or take it out of the connector? Do you have 12 v with the key OFF?
Yes I can communicate when i cut off the wake up signal wire right at the PCM connector(also measured it, there isn t any foreign voltage.) I also tought there will not be any communication. But there was The 5v reference at the sensors and also the comm with PCM. BCM does not send 12v when key off.
I am not sure what to do next. The PCM needs to be waken up to be powered up and starts receiving informations from other modules. Do you have 12v coming out the PCM power relay with key off or doors closed? Just trying to see how the PCM get the wake up signal. Does it crank with or without the wake up? I am guessing that it does not start when you have communication since you did not mention that.
I don't have a wiring diagram nor do I have the description and operation for the vehicle. If you could provide them, it would be very helpful.
Okay im back with new information. The wake up signal is good. I tought it could be bad ground at pcm so i did droptest at ground pins at ecm connector, but all seems good. I measured the air intake flap actuator that is constantly turning on and off, found out it has 2V to 3V always changing(thats why its always turning on and off) when it should have 0V when ignition on. The thing is actuator is not only component pulsating constantly on and off. when i unplugged ecm connector where is actuator pin, the harness had 0V but the pin at ECM had 2V-3V which should be ground pin for actuator. I just dont know how to get to the root of the problem. How to find the short?
Good point I also got the idea. When i Tried that on the actuator pin, the actuator went silent (obviously) but the other components were still clicking the same frequency like actuator did.
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