Seat Leon Mk2 No Crank, No Start, No Comm ECU

[mrsomebody]

I have a seat leon mk2 with no crank, no start, no ECU communication. Turning the key does nothing, no response from the car. Recently had 4 glow plugs replaced as well as injector #4, car stopped working after parking the car. I have tested the following:

- I have removed the starter relay and checked if its clicking, checked continuity between 30 and 87 and checked resistance between 85 and 86. all fine.
- I have removed other relays under the steering wheel, tested them as above and they are all fine.
- Tried to find 5V reference from the ECU, but instead found 0.19V volt in two connector places. One fuel related other not sure.
- one connector is fully covered in something (last picture below). when i inserted needle inside it came out black. i believe this is turbo related sensor.
- I have checked all fuses under the hood as well next to the steering wheel and all fine.
- Unable to read error codes as the computer connected via the OBD port is able to communicate with all modules except the ECU.
- Removed the ecu, tested the grounds going in to the ECU via ECU Connector A on PIN 1,2 & 4 and they are fine.
- checked all ground points i could find and they are fine.
- checked the voltage going through the PIN A 92 in ECU connector A (R1 Main Relay): 0.25V
- checked the voltage going through the PIN A 46 in ECU connector A (R4 Fuel Pump Relay): 2.8V
- could not detect any voltage going through the PIN 3, 5 or 6 in ECU Connector A
- removed the starter and it works as expected outside of the car
- when feeding the starter battery voltage where ignition signal would go the car attempts to crank, but does not start (even with easy start spray)
- engine not seized & starter confirmed working
- ignition switch does send out the signal as I've tested one of the switches going out of it when the key is in start position and I read battery voltage when turning key to start position.
- ignition voltage (pin 1) & battery voltage (pin 16) present in the obd port
- the starter relay R1, does not receive voltage on pin 87 at all. Grounds on 85 & 86 are fine. Battery Voltage present on Pin 30.
- there is no fuel going through the fuel rail to the injector 1 while attempting to start the car (while cranking). unscrewed the connector pipe to injector 1 and there is no fuel coming out.


Based on the above, is it safe to assume that ECU is potentially the culprit in all of this? I am detecting strange readings on ECU Connector A Pin 92 and 46, but I am actually unsure what they should be. It's either cable fault going to the ecu or the ecu itself. Any hints and tips regarding this issue greatly appreciated.

 

[Rosethron]

I might not help in anything, but those fuses arent messed up? Mine looks like this.

 

[mty12345]

I'm not familiar with the MK2 and I don't have a wiring diagram, but if you have battery voltage and grounds to all the right places on the ECU connectors, but no communication and no 5V reference, then probably 95% certain it's the ECU itself. If it was a CANBUS communication issue then you should still have 5V reference coming out. You can double check the CANBUS system by disconnecting the battery and meausuring between pins 6 and 14 on the obd port, should be 120 ohms or very close to it.
One more thing to check would also be the pin fitment on the ECU plugs, make sure no pins are loose, corroded or spread apart and not making a good connection.

If it happened immediately after the glow plug/intector work, then before fitting a replacement ECU, I'd make sure there is no fault there, like something possibly shorting battery voltage to the ECU etc.