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Go Back   TDIClub Forums > TDI Model Specific Discussions Areas > VW MKIV-A4 TDIs (VE and PD)

VW MKIV-A4 TDIs (VE and PD) This is a general discussion about A4/MkIV Jetta (99.5-~2005), Golf(99.5-2006), and New Beetle(98-2006). Both VE and PD engines are covered here.

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Old March 22nd, 2000, 02:00   #1
christi
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Location: Ruislip, Middlesex, UK
Default 96/97 Passat TDI cruise control, how does it work?

Given the number of speed cameras that we have in the UK now, and the amount of motorway driving I do, I fancied adding cruise control to my Passat. UK Passat TDIs don't have cruise control.

I noticed in the repair manual that cruise control is there in the circuit diagram for the TDI engine code 1Z like mine.

I pulled the trim off and found the connector which goes to the ECU, which is for the cruise control switch. "Simple" I thought "just buy a switch and hook it up". Wrong!

Because I'm mean (or sensible) I rigged up soem switches to try it out, before buying the proper VW part. It doesn't work. Maybe VW put different code, or a jumper inside the ECU to enable the cruise control.

Some questions:-
Presumably the cruise control doesn't work in neutral? in other words it keeps constant speed rather than constant rpm?

The manual isn't very clear on how to use it. Is this correct? :-
Switch cruise control to on.
Drive up to desired speed.
Press "set" button.
Remove foot from accelerator, and the car keeps its speed.

If the brake or clutch is pressed then the cruise control switches off, until you slide the switch over to "res". Does the car then accelerate back up to the set speed by itself? or do you have to press "set" again.

If you press the brake, and then accelerate to a new speed, and press "set", does it then hold that speed? You don't have to press "res"?

------------------
1996 Passat Tdi estate (wagon (variant))
See my Peugeot / Passat site
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Old March 22nd, 2000, 04:29   #2
cars wanted
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Default Re: 96/97 Passat TDI cruise control, how does it work?

The correct answer to all your questions except the 3rd one is yes.
1. The cruise control is supposed to work only at speeds above ~25 miles an hour, although I have not tested this feature. I suppose that means that it is a constant speed control.
2. In spite of your manual, it appears that you do understand how to use the cruise control.
3. Yes, the car does accelerate as needed to resume the previously set speed. You need not press the "set" button again.
4. You surmised correctly. The "set" is used to reset the cruise control to a new speed. If you wish to go faster, you can accellerate directly to the newly desired speed and then press the "set" button again. It is not necessary in that case to use the brake or clutch pedal to disengage the previously set speed.
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Old March 22nd, 2000, 05:26   #3
christi
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Default Re: 96/97 Passat TDI cruise control, how does it work?

Thanks,
I just tried out again at nearly 60mph, and it still doesn't work.
One of the four wires actually has power on it, I'm convinced that it is the right connector, the colours match perfectly those in the wiring diagram.
Damn, VW must have disabled cruise control functionality in my ECU. Damn, damn, damn, took all that trim off for nothing >
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Old March 22nd, 2000, 08:58   #4
Peter Cheuk
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Default Re: 96/97 Passat TDI cruise control, how does it work?

It's probably in the programming on the chip. I wonder if it is something that needs to be activated at the dealer?
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Old March 22nd, 2000, 09:27   #5
Karl Roenick
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Default Re: 96/97 Passat TDI cruise control, how does it work?

Yes, that is true for at least, I think, 1998 and later models.
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Old March 22nd, 2000, 18:49   #6
WestCoastGhost
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Default Re: 96/97 Passat TDI cruise control, how does it work?

There is one other 'feature' I'll mention. You can also accelerate by holding the 'res' switch against the switch stop. It acts just like the accelerator pedal. I don't know if that will help you but I wanted to mention it in case it did help.
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Old March 23rd, 2000, 00:55   #7
T5TDI
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Default Re: 96/97 Passat TDI cruise control, how does it work?

Christi,

I remember seeing a post about this from a guy in Eastern Europe about this a couple of months ago. He insisted that you only had to fit the switch. This stuck in my mind because the question came up in a mag I read, 'Can C.C. be retro-fitted to vehicles with drive by wire?' Unfortunately they are not on line so I'll let you know what they think when they next publish. It's a camper mag and many campers are based on the TDI Transporter.

My T4 van has the C.C. option fitted and it works as you say.

The option of C.C. costs a lot more than the cost of a switch. But I think you are right, VW have deliberately disabled the C.C. part of the ECU. There are ECU specialists around so it might be worth asking them, or maybe ask VW UK and see what they say. I'd be interested to here the results. Good luck!

Although I can't promise an immediate response as I'm quite busy at the moment, I'm quite happy to apply any test to the wiring of my enabled C.C. you ask.


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Old March 23rd, 2000, 02:32   #8
christi
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Default Re: 96/97 Passat TDI cruise control, how does it work?

Links to others discussing the same:-

http://forums.tdiclub.com/NonCGI/For...ML/000507.html
http://forums.tdiclub.com/NonCGI/For...ML/001022.html
http://forums.tdiclub.com/NonCGI/For...ML/001456.html
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Old March 23rd, 2000, 05:11   #9
RobStone
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Default Re: 96/97 Passat TDI cruise control, how does it work?

Christi, I think I've found the Gute-Fahrt articles (unfortunately not for your Passat B4 or my Golf A3):

Audi A3 TDI
Sharan TDI
Golf Mk4 TDI

They're "automatischen Geschwindigkeitsregler" automatic speed governor (abbreviated to GRA) in the "BauPlan" section from www.gute-fahrt.de. The text that accompanies each picture is part of the bitmap and so can't be copy-n-pasted into BabelFish. The first one (Audi A3) looks to be a complete installation, from the pictures it seems that once the switch is installed there might be a bit of wiring to do, followed by a trip to the dealer's 1551 tool to get it all to work.

------------------
1996 Golf III TDi (current)
1988 Golf II 4+E (previous)

[This message has been edited by RobStone (edited March 23, 2000).]
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