Galaxy in Emergency Mode: Error Codes & Fixes

Hello everyone, I'm new here and I'm having a small problem. I drive a Ford Galaxy (WGR) 1.9 TDI, year 1996. I recently replaced the brake light switch, and since then, the car has been in limp mode.

Error code read: 4 errors stored.
533 Air mass sensors (short circuit to positive).
539 Fuel Temperature Sensor (Go to the post...Signal faulty)
522 Coolant temperature sensor.
777 Pedal Position Sensor.
Error codes cannot be deleted.
The glow plug indicator light starts flashing after just a few seconds of starting the engine.
Is there any wiring harness in the control unit?
Why are there two brake light switches, one for the brakes and the other for the cruise control (which I don't have)? What is the function of each?
I would be very grateful for the help.
Best regards,

Well, those are almost certainly electrical faults, and likely occurring outside of the control unit.

You need to check all the wiring, as you mentioned it started happening after you replaced the brake pedal switch (and I'm curious why you did that). Since you know exactly what you disconnected and reconnected, I would start troubleshooting in that area again.

All TDIs have two brake pedal switches (or contacts) and one clutch pedal switch, both for safety reasons, as the accelerator pedal is fully electronic, and also for various comfort functions.

zoray wrote:

The brake light switch was replaced, and since then, the car has been in limp mode.

Okay, then let's start right there... or rather, what was the reason for the change?

zoray wrote:

Is there any specific pathway in the control unit?

A blown fuse can cause such symptoms, depending on the overall circuit configuration.
Has this been discussed here before? -> Search function

Thank you for the answers.
The reason for the change was that the indicator light was occasionally turning on. I didn't think much of it, but then I was informed that my brake lights weren't working. I investigated and opened the cover, checked if all the bulbs were okay, but they were all fine. I pressed the brake pedal, but nothing happened. I removed the brake switch and pressed it manually, but it still didn't work. Then I checked if there was any power reaching the switch, but there wasn't. I briefly applied power, and it sparked slightly. Of course, I also checked at the back to see if the positive or negative wire was connected. I didn't check for continuity.
"The fuse didn't blow, so I removed the entire footwell trim. I found another switch there. After checking and applying power, I connected the new one, and it worked. However, that day I didn't drive the car. The next day, I started it up, and as I accelerated, the preheating indicator started flashing again. I continued driving, but at 80 km/h, it stopped. I drove to the parking lot, and suddenly the idle speed was too high, 1300 rpm. I took the control unit home and read the error messages. I then checked the relays and noticed that relays 109 and 18 were very hot. I replaced them, but it didn't make much difference. That's why I suspected the control unit, as I had shorted the positive wire to ground. I also disconnected the mass airflow sensor (MAF), but it didn't change much. Well, now I have a mess."
Thank you in advance.

zoray wrote:

I removed the brake switch; I couldn't press it with my hand. Then I checked if there was any power going to it, and there wasn't. So I just applied some power, and it worked briefly. Bitte gib mir den deutschen Text, den du übersetzt haben möchtest. Therefore, my assumption was that the control unit was the problem because I had connected it to ground with power applied.

You can definitely destroy a mass-transit train in the MSG (presumably a game or simulation) like that.

Small consolation: As far as I recall, there have been cases (here in this forum) where the MSG started working normally again after the circuit board was repaired.

If I were to replace the engine control unit (ECU), what would happen to the immobilizer system?

zoray wrote:

If I should replace the control unit, what about the immobilizer?

Must be trained -> Search function.

hi,
"Fixed the error, mass transit plan approved, soldered the bridge, it works."
Thank you for the answers.
Sincerely,