Cruise control instalation and alternative parts.

[Robsey]

My pleasure - I like the challenge of working these things out.

I have updated "f".
I initially mentioned connecting a test lamp.
That is baloney...
It is just a matter of shorting pin 4 to earth, to make the vacuum pump motor run.

-------------------
Module pin functions are as follows:-

Pin 1 = Ignition Live feed from Cruise stalk switch pin 4.
(Black or Black/Blue)
12 volts with ignition on and cruise switched on.
0 volts at all other times

Pin 2 = Set switch from Cruise stalk switch.
(Red / Yellow).
12 volts with ignition on, cruise on and Set button pressed.
0 volts at all other times.

Pin 3 = Pedal Switches.
(Red / Black)
12 volts with ignition on, cruise on and either pedal depressed.
0 volts at all other times.

Pin 4 = Vacuum Pump Feed.
(Brown / Blue).
Acts as ground side of fuel pump.
ECU sets pin 4 to ground when cruise is active.
Open circuit from ground at all other times.

Pin 5 = Speed Pulse sensor.
(White / Blue)
Assuming a 5 volt square wave.

Pin 6 = Resume switch from Cruise stalk switch.
(Blue)
12 volts with ignition on, cruise on and Resume button pressed.
0 volts at all other times.

Pin 7 = Vent Valve Control.
(Green / White).
Acts as ground side of vent valve solenoid.
ECU sets pin 7 to ground when cruise is active.
Open circuit from ground at all other times.

Pin 8 = Module Ground Wire.
(Brown)
Shorted to ground at all times.

[maxstu]

Everything 100%. Including VSS
So going to plug in the ECU module and go for a test drive. AGAIN!

If nothing happens this time the only conclusion is naff module.

Many thanks for all your help.

Off we go again. Dual carriageway 10 miles away.

[Rascal]

Do you remember I had the exact same issue.. Did all the bently test. They were fine but no cruise control. Then I unplugged then replugged the ecu, has worked ever since. Over 6000 miles on it now

[maxstu]

Do you remember I had the exact same issue.. Did all the bently test. They were fine but no cruise control. Then I unplugged then replugged the ecu, has worked ever since. Over 6000 miles on it now

Hi Russ,

Yes l do

Ive re-read this thread you started so many times, and you rightly deserve 100% credit for being the pathfinder, so many times to check if l had missed something or a minute bit of detail from your install.

Ive been out for a extended drive today and success is mine. It does take a little getting use to. It's not instantaneous like a modern vehicle. And lm still uncertain whether it has a safety feature to prevent use under 45mph?

Anyhow, perseverance has paid dividends! It holds well at 55-65mph. RESUME allows user to return to set cruise speed if CC is cut momentarily. But being vacuum and bellow to rear of vehicle, there is a delay which one needs to accept and get use to.

Two issues caused the faulty CC. Nothing to do with it's design. Both were the installer's (me) failures to understand how to properly test the loom and VSS.

Im using an ECU module from a 1985 Jetta. It has an additional 9th pin outside of loom plug area. I thought leaving this unattached would not matter as the main 8 pin loom already has an earth at No 8 pin. But perhaps No 9 pin needs earthing to chassis too? So l fitted one. Why it needs earthing too? No idea I will test again without pin 9 to see what happens.

Secondly the power for the VSS (variable speed sensor) shares the same 12 volts wire going to the module loom. Most of the wiring is temporary stuff for now (and l will secure all connections with solder or proper connectors with sleeves once lm confident it's all correct) and l used a scotchlok to connect these two. However the VSS wire didnt get a secure power source causing it to fail when driving. Okay when static though.

9th pin on CC module



Shared power from G5 for CC loom and VSS. Never use scotchloks



As l said earlier, it's not exactly like a modern system. It takes a bit of time to kick in. So get up to speed. Switch on CC power and hold SET for the pump to start pulling vacuum. It may require pushing down SET for three or four seconds for it to match your vehicle's speed. The faster you are going the longer it takes. Then you will notice the throttle pedal going light, a tiny bit of acceleration, now release SET and then it settles.

I have joined the T3 cruise control club.

Many, many thanks to all contributors. But especially Rascal and Robsey for pulling my dead weight along. I couldn't have done it without your help and patience.



Regards
Stuart

[Robsey]

Yayy!!

Good man - got there in the end.

Minor thought.

If the vacuum is slow to build up, the quickest way to improve this would be to fit finer bore vacuum tubing.
Or a more oomphy pump.

But if you think that you can live with the delay, then leave as is and tick off another job from the list.

[maxstu]

Yayy!!

Good man - got there in the end.

Minor thought.

If the vacuum is slow to build up, the quickest way to improve this would be to fit finer bore vacuum tubing.
Or a more oomphy pump.

But if you think that you can live with the delay, then leave as is and tick off another job from the list.

Probably a lazy pump. Yet l've nothing to compare it against. Besides, I cant see how it would work any other way? When testing the vacuum bulb in the engine bay with a three part test lead l made and a battery, it takes about three or four seconds to fully deflate, or go to maximum vacuum.

Im leaving as it is while l get used to how it functions.

Regards
Stuart

[Robsey]

That was one reason why I plan to use the GM / Saab version.

Based on my retro-fit cruise on my Cavalier mk3...
There is no delay when you hit set.
It is purely a stepper motor that pulls the accelerator cable... no vacuum to build up.

Resume can be a bit intense though...

There is a 50mph section on the clockwise M60 as you approach Stockport.
I used to cruise down the eastern side of the M60 at 70mph.
Disengage cruise for the 50 zone,
then press resume at the end of the zone.
Blimey the Cavalier kicked you in the back to accelerate from 50 back up to 70.
At bit un-nerving when it first happened.

Probably not surprising in a 113 bhp, 1 ton car as opposed to a 2 ton van.
Being a good chunk heavier I am sure my 112 bhp DJ powered van would not be quite so intense.

Note to self - do not hit resume when you are travelling 20mph slower than the previous set speed.

[maxstu]

Ha! Good note Robsey.

To be honest l need to give it a few more test runs. But the only suitable place is about 10 miles from my home. So each test is costing me £7.50 in petrol

One issue l need to absolutely confirm is whether there is a safety feature preventing CC operating below a certain speed. Say 40 mph. Im not sure how though.

[Robsey]

The only way to know for sure is to take the van out when the local roads are quiet, and try to engage cruise when bimbling along a straight 30 mph road.

Is 40mph a preset speed limit on the VW CC system.??

Mine (GM / Saab) cuts off below 14mph, so okay for cruising around the dozens of new 20mph zones popping up around the Manchester area.

To be honest, the cruise should not 'self engage' anyway.
Keeping it turned off at the switch (or a separate isolator switch) should prevent any mishaps.

The cruise would have to be on, and you would have to be in the habit of pressing the set or resume button when faffing with the stalks whilst driving.

As the feature was not there before, you are hardly likely to press the buttons out of habit... just by faffing and fidgeting.

Another thought, it is only the resume function that could potentially cause the van to accelerate to an unexpected speed. (As per my note above)
Set would hold your current speed.
You could leave the resume wire disconnected.

As long as the off and / or brake pedal switches work, you should not come to any harm.

You have already said, cruise is a very slow reacting system, so unlikely to take you by surprise.

Try not to over-think or worry about it.
It will be fine.

[Rascal]

There definitely is a feature that it will not allow it to engage below 40mph.. Mine simply won't.
I simply press set and then completly remove my foot from the accelerator... Having used the system for several thousand miles. My thinking is that the system. Works buy counting the pulses from the speed sensor... And then matching them to as when set was pressed.. If you keep your foot on the accelerator then the system is essentially receiving the correct amount of pulses and won't activate the pump or will only activate briefly for minoor changes in your foot position... But if you remove you foot completely then. The pump instantly activates and I find its accelerated and has matched the set speed within 2 seconds. That just how I use it anyway...

[maxstu]

Good info from both. Thanks very much.


I need to test whether my SET button activates as it should then. I accept the delay is part of the old fashioned vacuum system. I felt l needed to keep the SET button pressed until the system caught up with the current speed. Will try alternative methods for testing on Tuesday. Perhaps the fierce headwind l was driving into played a part in a slow climb to SET speed.

I noted the speed sensor did increase and decrease speed according to road incline or decline. Yet a bit delayed. It doesnt help having a wildly inaccurate speedo (on standard tyres/wheels btw) showing 60mph on speedo/56mph on GPS. So l will set up a satnav on next testings.

How to test the 40mph cut off point? Again by using a GPS signal on my phone or satnav l suppose.

Still well chuffed though. And if done again, now knowing what l know, could probably sort it in a leisurely day.

Thanks guys.

[Rascal]

The delay on my system is just over a second between pressing and feeling the vacum pump take over.. With virtually no drop in revs... And as for the below 40mph Saftey that's definitely a thing.. My speedo is in km. But I'd say 40mph is correct