Cruise Control Operation

[bugfil]

I have a VW cruise control unit(VPC-Volkswagen Products Corporation), Part # ZVW201709, Type 2, and manual transmission kit ZVW201728 that I bought NOS on the Samba many years ago and installed it many years ago too.
It works well as long as you don't have to go up a hill that's steeper than 3 degrees.
I have a question about the operation of the unit. When I apply the brakes while using the cruise control it slows down as long as I am depressing the brake but when I let up on the brake pedal it starts to accelerate again meaning the cruise control is still engaged. This is a little disconcerting when you are used to a modern cruise control that cuts off when the brake pedal is applied. There is a cut off switch on the clutch pedal but not on the brake pedal.
Is this the way this cruise control is designed to operate or did I install it incorrectly? Does any one else have one of these installed on their bus that could comment on whether theirs work this way too?
The installation manual mentions an operators manual but I did not get that with the unit so I'm not exactly sure how it is supposed to operate. It is a manual transmission in a 78' Champagne edition Westy.
These units seem to be pretty rare and I have found very little information online about their operation.

[busdaddy]

I see a clutch switch, does it disengage when you push the clutch?
There must be a brake switch, I've never seen a cruise control of any brand that didn't cut off when you touch the brake, what's the wiring diagram in the install instructions show?
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[Bobs67vwagen]

Yeah something is not right on this. When the brake is applied the cruise should be deactivated by a switch on the pedal. Maybe another Audi/VW car of the same period that has cruise control might be a place to start looking for wiring and components for troubleshooting advice and information.

[rsbadura]

[bugfil]

Yes Busdaddy, the clutch disengagement switch does work correctly. There was
no wiring diagram provided in the install instructions. Here are the other two pages provided in the install instructions. I have not gone back in to look at
the wiring etc. yet. I believe the system has always been this way since I installed it so it may be connected incorrectly but I don't see anything in the instructions that describe or show a switch at the brake pedal.
Thank you for the manuals "rsbadura", having a wiring diagram to look at is very helpful. On page one of the manual I see a picture of the chrome stalk and switch end that looks like the one in my set up so they may be the same or close. I see in the trouble shooting section that when the bus continues to accelerate after releasing the brake pedal it is either a faulty engagement switch or faulty regulator. Sounds like I may need to learn more about how this system works to determine what's wrong.
Thanks "Bobs67vwagen" good idea about looking at other vVW/Audi models from the same years, that may help me see if something is missing from my cruise control.
I'll let you know what I see when I take a look at the cc system tonight.

[bugfil]

Hi, so I pulled the front pan to look at the cruise control parts. I didn't see anything I can recognize as being wrong, of course that's with my very limited knowledge of cruise controls and how they work. How often does a guy who has worked on aircooled VWs for 40+ years need that knowledge?
Here are some more photos, definitely no switch for the brake pedal.

Here you can see the switch on the clutch pedal.

I'm thinking now that maybe the unit is electrically tied to the brake light as the brake does seem to shut the cruise control off temporarily. I'm not fighting the motor still trying to drive the vehicle forward when the brake is on so I believe something is cutting power to the cruise unit.

Does anyone out there know how to test for proper function of the different parts of the cruise control. I'm particularly thinking of the regulator since the information rsbadura provided says in the trouble shooting section that when a cruise unit acts like mine does it's either the switch or the regulator that is not working properly. Any ideas are greatly appreciated.

[busdaddy]

I wonder if the resume switch is stuck on, although it quits and doesn't resume when you clutch, correct?

No idea on the "regulator", is that the thing with the speedo cable on it?. It kinda looks like the GM system from that era, I figured out how that system worked years ago so I'll try and recall where I found that info.
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[67rustavenger]

I would move that clutch switch to the brake lever.
The way it's currently installed, when you depress the clutch pedal while driving, it seems to me that the engine would rev up before the pedal is completely down and disengaging the CC.

I never liked those bead chain CC's.
We installed one in a 32 Ford Coupe some 40 year ago and had an incident when we hit the accelerator and the chain slack got wrapped around the brake lever. We almost hit a Walnut tree before we could switch off the engine.

To the person that commented on later model CC in their driver.
I have a 2003 EV Weekender and a 2020 Tundra TRD. I have to be careful driving the EV as the Tundra has radar detection and will slow mu truck as I approach a vehicle ahead of me when the distance closes rapidly.
My EV doesn't have the radar feature so, I have to remember to touch the brake lever in the EV when driving it and the approach distance closes in traffic.
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[rsbadura]

[mikedjames]

Read the first set of instructions you posted. There is a wire from the brake light switch mentioned in the bottom right paragraph.

There is no need for an extra switch on the brake pedal, there is already a switch.
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[bugfil]

So, I’m still trying to sort the problem out. Lots of ideas but nothing I’ve checked is wired wrong or connected incorrectly.
Mikedjames, I have read that part of the install section numerous times and double checked the wiring in the brake circuit, everything gets power like it should all the way to the CC regulator and power is cut when the brakes are applied. The problem is the CC comes back on when the brake pedal is released which it should not do. This is specified in the instructions too. Any ideas why depressing the brake pedal doesn’t cut the power for more than the time the pedal is depressed?
I’m wondering about the resume feature on this CC, which I haven’t checked into yet. There is so little information on these CC units that I can find even though these Dana Speedostats were use on many different vehicles.

[busdaddy]

The factory one in my Chev truck stays off after you touch the brake (separate switch on pedal), it'll resume when you poke the resume button, I can't remember if it remembers the speed when the ignition has been off.

Yours sounds like the resume switch is stuck.
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[blacka1vw]

Could there be an input switched between the brake switch signal and the clutch pedal signals? Maybe resuming after clutching could be ok.
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[bugfil]

The mystery continues but new information has been found. With the help of user "airschooled" I was able to access the owners manual that "sage79" had added to the technical section of the Samba forums back in 2009. The manual has a simple wiring diagram and a fairly lengthy troubleshooting section that describes how to test the various functions of the Cruise Control system.

https://www.thesamba.com/vw/archives/manuals/VPC_A...l_1976.pdf

I have been in the process of creating a mounting system for a universal brake light switch and wiring that in line with the clutch pedal switch allowing both pedals to shut the system off through the same circuit. Before I do that though I will do some testing first to try to narrow down which part isn't functioning correctly instead of bypassing the problem.
Is it the resume function or possibly the one relay in the system or something else? I'm now leaning towards thinking that it's the relay and when the brake pedal is depressed it releases vacuum from the regulator but doesn't send a signal to the unit to shut the power off so vacuum engages again when the pedal is released. We'll see if I'm right or totally wrong tomorrow when I get a chance to do some electrical testing.

[Opossum]

[bugfil]

Hey Opossum, thanks, that template is for the Cruise Control switch/arm that mounts to the steering column just under the steering wheel. I was referring to making a bracket that would allow me to attach a on/off switch at the brake pedal arm where there wasn't one originally.

[Wildthings]

I can see having a momentary cut off on the clutch pedal and a cut off that stays activated on the brake pedal. Can the wiring be swapped between the two?

[bugfil]

Wildthings, there is no physical switch on the brake pedal. Wires are connected
to the hot and cold side of the original brake light wires in the bus. The actuation of the brake light circuit is what shuts off the cruise control; supposedly. I'm still trying to figure out why it acts as a momentary switch when all the different installation and owners manual literature says the system should shut off completely.
I spent most of the day yesterday checking the physical parts and connections and had hoped to do the trouble shooting electrical tests but that's a 2 person job and I was working solo. I did figure out that the clutch switch is supposed to be pressed in when the clutch lever is at rest(not depressed) and when the clutch lever is depressed it lets the switch out and cuts continuity through the system. This is the opposite of how I thought the switch physically worked. I also sprayed the switch out with electrical contact cleaner and got it working much better, before the cleaning it would light up my test light but wouldn't show continuity on my ohm meter. Thanks for the comment, I'm hoping that some of the comments here will give me an idea that helps me figure this out.

[busdaddy]

I'm still going with stuck resume contacts or touching wires.
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