STG Glitches Every 3 Minutes

I had a used engine control unit (ECU) installed in my Audi A6 90 PS TDI, manufactured in 1996, after the original one failed. The engine and everything else ran perfectly after the replacement.
After that, I bought a pair of chips from Digi Tec, installed them, and everything seemed fine. However, during a highway drive, I noticed that if I didn't press the brake pedal at least once every 3 minutes, the control unit (ECU) would reduce the power output as if it were running on the original settings. When I did press the brake pedal, it would function normally again. I also hear a clicking sound coming from the ECU after about 3 minutes, and it stops when I press the brake pedal.
The error code indicates "brake pedal sensor - implausible signal."

So, I removed the cover from the brake pedal and disconnected the wiring from the two brake pedal switches. There was a black switch with a red/white and a red/gray wire at the bottom, and a light-colored switch with a red/black and a red/yellow wire at the top. However, after disconnecting the wires, nothing happened except that the brake light stopped working.
Can anyone help me figure out what this might be? It could probably just be a problem with the switch.
Is it possible that a cable needs to be disconnected or something like that?

You're very welcome, BASTI.

That sounds like an inverted switch.

Hello,

The brake light switch is active, but if the pressure in the braking system is below a certain threshold, the above error is stored. This usually indicates a brake light switch that needs adjustment. It's strange that this only started happening after the chip tuning. Has the vehicle been driven frequently over rough terrain recently?
As a first step, adjust the switch.

- Remove the switch by rotating it 90 degrees clockwise (make sure to unplug the connector beforehand).

- Pull the switch's plunger completely out.

- Press the brake pedal all the way down.

- Reinstall the switch by turning it counterclockwise.

- Release the pedal, and the switch will automatically adjust.

- Attach the plug.

Hello.

I found this article while searching. I'm having the same problem. However, it's not the switches; they are all set correctly.
After replacing the control unit, I now consistently see the values as 110 in VCDS. When I press the brake pedal, the last '0' also changes to '1'. The car drives normally, but I can't activate the GRA (presumably referring to a specific function). The automatic transmission coding is also set, but it shows as 00002.
I have no idea what that is.
Could it be that the new engine control unit (ECU) has a different pin configuration?

Hello!
no, it's not about the configuration, but definitely code the DTG to "automatic" if it is one!! I've had my share of problems with that. You can probably explain why some bits are set to 110, even if you only have 2 pedals .
Sure, here's the translation:

"gruzz" translates to "greetings" or "regards" in English. It's a casual way of saying hello or goodbye.

Hi there,

I also experienced this problem during my engine swap. According to the original wiring diagram for my 1997 Golf AFT engine, the brake pedal switch (not the brake light switch) grounds to the negative terminal.
After replacing the control unit (likely from a newer Passat), I experienced the same issue.
In the new control unit, the brake pedal and clutch switches must be connected to the positive terminal (terminal 15). Additionally, the newer control units have an extra connection for the GRA (Gearbox Ratio Adaption), which is pin T68/58 on the control unit. This must be activated, otherwise the GRA will not function. The simplest solution is to connect pin 58 to pin 66.

This only applies to the MSA15 device with the single 68-pin connector.

greetings
dieter

T3 Syncro, 16" AFN.

Hello!
No, it's not related to the settings. But definitely set the DTG to automatic if it's a DTG device!! I've had my share of problems with that too. You can probably explain why certain bits are set to 110 even if you only have 2 pedals.
gruzz

I didn't express myself clearly. I have a switch that is also coded, and I meant that it can't be due to that.



In the new control unit, the brake pedal and clutch switches must be connected to plus (terminal 15). Additionally, the newer control units have an extra connection for the GRA (Gear Range Actuator), which is pin T68/58 on the control unit. This must be activated, otherwise the GRA will not function. The simplest solution is to connect pin 58 to pin 66.


The bits from the GRA module all match when checked with VAG COM. They respond correctly to all the settings I make on the control lever. Could it still be that it doesn't work despite that?
So, I need to connect the clutch switch and the brake pedal switch to the positive terminal.
Which one is the brake pedal switch? Think about it, it's probably the upper one!
To connect the switches, I just need to connect one of the wires from each switch to the positive terminal. But which one? I don't have a wiring diagram. My car is a Golf 3 with a 1Z engine from 1996, so it also has a 1Z wiring harness.
Can someone tell me the cable colors?

So, I have to connect the clutch switch and the brake pedal switch to the positive terminal.
Which one is the brake pedal switch? Think about it, it's probably the upper one!
To connect the switches, I just need to connect one of the wires from each switch to the positive terminal. But which one? I don't have a wiring diagram. My car is a Golf 3 with a 1Z engine from 1996, so it also has a 1Z wiring harness.
Can someone tell me the wire colors?


Hat sich erledigt. Danke an Dieter. Habe die Schalter auf Plus geklemmt und siehe da, es geht.!! Happy

The bits from the GRA are all correct when checked with VAG COM. They respond to everything I adjust on the lever with the correct combination. Could it still be that it doesn't work even then?

Bad news: It's not working. The second bit from the right is not going to 1.
Is that due to the missing pin on the control unit? Where exactly should I make the connection? Directly on the control unit, or can I do it on the cable under the steering column? Sorry for the question, but I unfortunately don't have a wiring diagram.

Hi there,

Perhaps you should first obtain a circuit diagram, for example, from here:
http://volkswagen.msk.ru/

"If you have an older wiring harness, pin 58 in the T68 may not be connected. In that case, you'll need a suitable connector pin to bridge the connection. I removed one that I didn't need and used it for that purpose. --> wiring diagram."

greetings
dieter