Seat CAYC Glow Plug Control & Coil

During the drive, the engine check light and the glow plug indicator came on. The owner continued to work, and after work, when he tried to drive home, the car wouldn't start.

I was thinking that the error messages might be caused by a faulty sensor.



The following pins are used for the donor reference voltage A: T94/14 5V - T94/79 Ground, T94/15 5V - T94/74 Ground, T60/10 5V - T60/51 Ground.

Okay, so I disconnected the differential pressure sensor G450, the boost pressure sensor G31, the EGR potentiometer G212, the throttle potentiometer G69, the potentiometer from the VTG control unit G581, and the fuel pressure sensor G247, and then tried to start the engine. It started, but then I turned it off and plugged in one sensor again, I think it was the G581, and it wouldn't start anymore.

I then disconnected the remaining sensors (G40, G79) that were connected to the reference voltage A. When measuring the voltage at each individual sensor, the power supply voltage was 0.38V. The measured voltage decreased as I disconnected more sensors. When I disconnected all of them, I could only measure 0.13V at the corresponding pins.

Finally, I measured the voltage at G28, and it was 5V, which it shouldn't be, as it shouldn't be connected to the sensor reference voltage A. All the other readings were 0.13V.

I then removed the control unit and checked the wiring for short circuits, but I couldn't find anything (although I only checked it with two sensors). I also checked the connection from the two sensors to the control unit, but that was also okay.

I then wired the control unit on the table and checked the pins for the sensor reference voltage A without load, and I did get the 5V there.

The control unit was reconnected to the T60 wiring harness, and only the power supply was connected to the T94 using individual wires. I was now able to measure 5V again at the sensors that are connected to the T60 connector.

T94 connected, and the sensors are showing 5V again. The motor has also started up again.



What I also noticed is that the battery maintainer didn't turn on, and the sensors weren't receiving 5V. It charged with 30A, but then dropped down to only 19A after the ignition was on for a while.

Now that he's leaving again, there are only 10A seats left.



What do you think, is the control unit malfunctioning or just "frozen"?



I had a similar issue with a gasoline-powered A6. In that case, the relay responsible for supplying power to the control unit wasn't being activated. I spent a long time searching for the problem until I finally opened the control unit and left it overnight (it was winter) inside the house. The next day, the car started again and has been running fine ever since (for 6 months).

Okay, I'm ready. Please provide the German text you want me to translate.

Hi,

Checked the wiring harness for any chafing? Are the battery connections properly tightened and is the battery in good condition? I suspect the issue lies in this area, as several control units are reporting a low voltage.

Best regards, Rainer.

The low voltage is likely due to the towing, and it has managed to start the ignition.

"There might be a blown fuse in the engine control unit. Check the fuse box."

Is this a question, or have you experienced this before? The car has been running again for 3 weeks, but I haven't found anything wrong.

The mileage readings associated with each error in the car scan refer to the commute to work or the tow truck trip?
It appears that the undervoltage in the on-board network occurs first (109114 km, with an irrelevant date), followed by the reference voltage becoming too low (109118 km). The exception is the error related to the load signal for the generator terminal, which has occurred 49 times over the past few months.
hg
Herbert.

I can no longer reconcile this. When I had the car scanned, it showed 109,110 km, and I only drove it after I had everything checked. This doesn't add up; the scan showed 109,110 km, but the error codes were logged at 119,118 km.