GRA Switch and Speed Signal

Okay, first of all: I have searched the forum for GRA.

My car: Golf 3 TDI, manufactured in 1996 (but appears to be running as a 1997 model, at least according to the wiring diagrams)

I have a problem. Similar to the 'Tempomat Installation Problems' thread, one of the pins is not connecting in my case.

Display Group 6 Field 3:

000000 Cruise control off
000001 Cruise control on
000101 Press the button
001001 RES Position
100001 Clutch engaged
010001 Brake applied

1. Problem: My switch has 4 wires: Set, Reset, and I/O. I have read that it is possible to 'turn it off by tapping 'off''. So, press the switch towards the speedometer, or what does that mean?

2. Problem: I tried to read Group 6 using VAG-COM, but I'm not getting any km/h signal on the PC. Where is the signal actually coming from? I have three blue connectors with blue/white cable in the wiring distribution box. One goes, as far as I know, to the radio, one to the control unit, and I suspect the third goes to the speedometer. What kind of signal can I measure there? Digital signal? Analog signal?

So, es scheint, dass abgesehen vom fehlenden Signal auch das 'Aus-Signal' fehlt. Or is it even missing in some versions?

I hope this is enough to give you an overview. Does anyone have a tip on where I should start my search?

Best regards, Sebastian

Hi,

Switch broken or incorrectly wired...

Hello, Rainer

With the words 'switch broken or incorrectly connected,' I unfortunately can't do much.

1. Original wiring, therefore correctly connected (confirmed by the specialist workshop!).
2. The switch was tested by me. There is current flowing during operation, and there are no illogical resistances, therefore I also rule out that it is broken.
3. Cables are fine.

Actually, I'm more interested in the question of where this 'tap to add 1' button should be located, which adds the second permanent 1.

This issue seems to have also occurred in other TDI units. Did the simple replacement work?

I'm sorry, but I've had the experience that the mechanic (actually from 2 different workshops) simply said, 'The switch is broken,' because 'they didn't want to find the exact cause.' My diagnostics, as mentioned, showed: illogical speedometer signal, no speed display in VAG-COM, and the missing 1. (Besides that, he also overlooked the fact that my turbo was malfunctioning, even though I had told him about the performance loss). I have now decided to investigate this further. Where could the switch be defective? The 'on,' 'off,' 'set,' and 'reset' functions are working. Could there actually be another switch (that wouldn't be shown on the schematic) that is in a continuous state, thereby preventing the second 1?

If power on, power off, Set, and Resume functions work, what else do you want? As far as I know, cruise control doesn't really do much.

Best regards, WarLord

konfi wrote:

Power on, Power off, Set and Reset functions work.

What is your problem? That's all GRA can do.

Quote:

Could there actually be another switch (that wouldn't be shown on the schematic) that's connected to a continuous circuit, thereby preventing the second 1?

Why might a schematic not represent something?

The switch on the steering wheel lever has three positions: Off, On, and RES (reverse). The Resume Position is just a button press, otherwise the switch is always in the "On" position.
Another function depends on the lever used. To activate this, the switch can be moved from the "On" position to the "Off" position without immediately locking into the "Off" position. This is the "Tap-Off" function. This steering wheel switch has not been used since 1995, so you don't need to look for its function.

Hi,

Perhaps the original source with the "typo" was not entirely complete.

Besides the version Bertil wrote about, it could also mean something completely different:

Pressing the brake or the clutch will do exactly what you want.

Best regards,

Jan

Question:
What should a "tap to dismiss" function do for a sense?

That means the switch is not broken, which is exactly what I've been saying all along. So, it seems my problem is with the speed signal. Can anyone help me with this?

Hello,

Is your GRA going now or not?
As far as I understand, you have 2 problems:
- no mph display in the engine control unit
- 2nd bit from the right at GRA/Pedal position always 0

Hello, Rainer

Okay. 2 problems

GRA doesn't work . (without the speed signal, there's no wonder) I don't know what the 2nd bit from the right is for.

Regarding the radio signal: my radio seems to have never received a signal either, as the radio's volume control never worked. But doesn't the speedometer also use the same signal? So, the signal is actually there. Maybe the connection between the instrument panel and the TV13 wiring distributor is just not working properly anymore. Has anyone had experience with this?

Hello.
A small question at the side:
Did you add the GRA? Or was it already there?
Once you've installed the upgrades, you still need to activate them.
'There is a 'KEY' that must be entered using the diagnostic device.'

first, the GRA will work.

Best regards
Micha

konfi wrote:

...GRA doesn't work. (without the speed signal, there's no wonder)....

If the speed signal (which the GRA needs) is actually missing from the engine's ECU, then the speedometer will also not function.
The VAG COM, also known as the service computer, sometimes doesn't display speed information on my 1Z. Despite everything, the GRA functioned.
Let's check the brake light switch. It's a two-way switch. If the switches don't open and close absolutely synchronously, then the GRA (presumably a system or device) won't work... without any error messages. That was the problem with my 1Z, as suddenly the GRA no longer worked.
Also, make sure to check the clutch switch as well.
Here in the forum, the following information is provided on how to adjust the switches (search function).

Do you have the original factory radio installed?
D.h. it's not possible here to somehow 'short-circuit' the speed signal, because a wiring configuration doesn't match?

@Micha: The GRA has been unlocked. And also, second-hand, but still functional.

@Rainer: The radio is not original, however, it supports the GALA function and has the same wiring on the DIN connector. Grundig Radio (doesn't really matter, but if anyone asks)

@Bertil: Ist das Geschwindigkeitssignal nur manchmal weg, oder dauerhaft? Bei mir ist es dauerhaft weg. Ich werde die Bremslichter und Kupplungsschalter nächste Woche überprüfen. Meine Vermutung ist auch, dass das Signal vom Kombiinstrument nicht zum Leitungsverteiler weitergeleitet wird. The signal itself, according to your statement, is present.

Okay, so werde ich nächste Woche also hauptsächlich auf die beiden Schalter konzentrieren und den TV13-Verteiler überprüfen. Ich denke, dort sollte ein Rechtecksignal anliegen. Mal sehen, was dabei herauskommt. Thank you so far.

Hi,

The radio thing was just an idea, because while the JVC connector fit, I had to swap out some pins.
If the EDC does not receive a speed signal, the only option is to trace the wiring harness... the original design should ensure that the speed signal always goes to the EDC, because otherwise the EDC's damping function will not work.
So, it could be due to a broken cable or a corroded connector.
Do the speedometer and the instrument cluster receive the speed signal?
Do you actually have a manual transmission or an automatic transmission?

Hello, Rainer

konfi wrote:

@Bertil: Does the speed signal sometimes disappear? Or permanently?

It's not gone, but it's just not shown during the diagnosis (and it remains that way). This happens, but I don't know why.

Quote:

My suspicion is also that the signal from the instrument panel is not being transmitted to the distribution box. The signal itself, according to your statement, is present.

The signal from the instrument cluster has nothing to do with the GRA and is completely independent of it.
"The only important thing is that the engine control unit (ECU) processes the information from the speed sensor (which is why the speedometer works) and that the engine control unit also processes the information for comfort functions (e.g., jerk damping, throttle cut-off)." GRA).