after a few days ago I asked a few questions. Tempomat gepostet (and also got very helpful answers, many thanks at this point !), I am now at a point at which I could actually go to work - just missing a few details to make the puzzle fit.
The cruise control is certainly not the simplest system in the V8, as I had to find out, so I needed some time to look through it. Thanks to your help, the circuit diagrams and also the temp. image of Thomas (was found in one of your postings, I hope to understand it!). I'm just going to describe my idea, and you're telling me if I'm right or wrong. Here and there I have an unanswered question, maybe you can help me there, that would be great! I'm referring a little to the schematics, for the sake of simplicity, I hope that I don't go into too much detail.
First of all, the most incomprehensible for me: the pneumatics line. I now believe that the actuator connected to the gas train is controlled exclusively by the degree of vacuum controlled by the vacuum pump via the GRA control system. Am I right with that? That means there's no electronic cable on this actuator. I can't find it anywhere on the plans. A pneumatic hose with T-piece (a smart one and then the actuator) connects the valve to the brake pedal for the GRA and the vacuum pump, right? This hose runs between F47 and V18 on the schematic, correct?
Speaking of schematics: What is this four-wire strand on the top of each plan with 30,15,x,31 ?? Even mine. ET teacher didn't really look through it.
Continued in the program: Basically, this hose is a closed system when the cruise control is active. Sometimes more, sometimes less pressure, depending on what is required. If the brake is now being braked, the F47 valve is opened and the vacuum is immediately gone - so the gas also goes away and does not get in the way of the braking process. In parallel, F47 switches off the cruise control more or less when interrupted (so the solenoid valve opens in V18), as it interrupts the circuit, which is usually interrupted by a button or the snapping of the push button at the cruise control direction "off". Is this the right one so far? If I had a clutch, would it also interrupt this circle, correct? But it's gone.
Now my first important question: Is the electric motor running permanently in the vacuum pump and is only the solenoid valve closed if necessary, or is it only running if necessary ? Is there a simple method (please everything, just no lifting platform, currently no chance) to check whether the pneumatic hose is dense?
Is the valve in the brake actually not only a second redundant way to release the pressure in the case of failure of the electronics ? Otherwise I don't see much sense ...
Continue to the lever: Is my assumption that the individual manual switch at E45 on the right is the FIX key of the cruise control? And the push button of the 4-way switch? If yes, to the switch: I think position 1 is equivalent to "top", position 0 is the initial position (i.e. "on"), position 2 is "out" and position 2a is the engaged exhibition to the right. Is this so far ? Is it true that (according to the plan) the vacuum pump is supplied exclusively by the GRA control with juice and thus also via fuse 26 its current? If so, I can test the function of the pump by ampere measurement within the circle. Is the brake light switch the same as F47, or are these completely separate switches? I'm not that clear yet.
Why does the power for the S26 fuse actually come from the J217 transmission control unit? What is the point of this ? The one, that in case of failure of the transmission control the cruise control also switches off? Or that when the gearbox is switched off ( = engine off) is also the cruise control shut down? Another uncertainty :
Where in the engine compartment is exactly the actuator for the gas train? Unfortunately, the rep. guide is silent
...
Is there a printing error on page 6-2 for vertical division 17 and 18? According to legend, the mass 135 should be 132, right?
What is T4a good for? Is this a diagnostic plug or something like that? The four contacts are not connected.
Yes, well, I know, unfortunately, not a lot of questions and uncertainties, but maybe one or the other already has experience or still has an idea (Thomas?).
Thank you very much for any hint !
Best regards
Bastian
