Cruise Control

[Steve S.]

Greetings to one and all,

I'm at the state where I'd appreciate some hopefully confirmatory advice on this ongoing "investigation" before I end up with the dashboard sitting on the front seats akin to what Vanbursta had going the other day!

I've had the car for 18 months now, the c/c has never been reliable...well no surprise there I hear you say!...For example it might work if you drove over a catseye or a pothole on the lhs of the road before setting it, or it might work after a break in a journey. Once working it tended to stay ok until you switched the ignition off, then you had to try again from scratch.During the last 6 months it has ceased to work at all!

So far I have......Checked the fuses.

Replaced the rubber vacuum pipe to the pump.

Replaced the vacuum pump.

checked the brake pedal switch (electrical side) and setting

sucked the tube ,got movement of the accelerater actuater

brake lights working ok

All with no improvement.

Today I had the column shroud off again (I sprayed contact cleaner on before) and checked the multiplug connecter to the switch, it has 6 wires (whi. blu.red.bla.yel.bro) and discovered (using a bulb to earth) that there was no voltage at any of the pins. Now does this indicate a faulty control module, or something else?

Vanbursta ,you've been here before, what do you think? I'm hopeful that this might be the problem and even more hopeful that it is just a loose connection to it...I know it's a lot to hope for..forever the optimist but if bumps in the road caused it to work once, something may have dropped off!

Now I've been quoted

[Smilge]

Greetings to one and all,

I'm at the state where I'd appreciate some hopefully confirmatory advice on this ongoing "investigation" before I end up with the dashboard sitting on the front seats akin to what Vanbursta had going the other day!

I've had the car for 18 months now, the c/c has never been reliable...well no surprise there I hear you say!...For example it might work if you drove over a catseye or a pothole on the lhs of the road before setting it, or it might work after a break in a journey. Once working it tended to stay ok until you switched the ignition off, then you had to try again from scratch.During the last 6 months it has ceased to work at all!

So far I have......Checked the fuses.

Replaced the rubber vacuum pipe to the pump.

Replaced the vacuum pump.

checked the brake pedal switch (electrical side) and setting

sucked the tube ,got movement of the accelerater actuater

brake lights working ok

All with no improvement.

Today I had the column shroud off again (I sprayed contact cleaner on before) and checked the multiplug connecter to the switch, it has 6 wires (whi. blu.red.bla.yel.bro) and discovered (using a bulb to earth) that there was no voltage at any of the pins. Now does this indicate a faulty control module, or something else?

Vanbursta ,you've been here before, what do you think? I'm hopeful that this might be the problem and even more hopeful that it is just a loose connection to it...I know it's a lot to hope for..forever the optimist but if bumps in the road caused it to work once, something may have dropped off!

Now I've been quoted

[Steve S.]

Dear Bleeno,

An interesting theory.....unfortunately, impossible in this case, the car is an auto and so comes minus clutch! I've found a place in the USA that seems to refurbish cruise control units for about

[Smilge]

Dear Bleeno,

An interesting theory.....unfortunately, impossible in this case, the car is an auto and so comes minus clutch! I've found a place in the USA that seems to refurbish cruise control units for about

[Vanbursta]

Hi Steve

 

Yes I had exactly the same problem, I too checked the voltage at the steering column and the pump, the pump worked fine on the bench, there are 3 connections, one goes to earth one to the pump and the other to a relay in the pump, if you connect 12v across negative and the pump feed the pump should work, 12v across the negative and the relay connection and you should hear the relay in the pump click, no voltage to the switch connector at any time though.

 

I had exactly the same symptoms as you and it was the control unit. TIS mentions 12v at the steering column end, but even with a working unit this is not the case, none of the terminals is energised until you reach over 28mph. Don't take any notice of the TIS when it tells you to remove the dash panel either, you don't need to do this as if you remove the radio, climate control panel and the cubby box, you can then remove the finishing panel and then the panel that holds the switches in, once you have done this you can remove the single philips screw holding the CC unit in place, I think you have to remove the passenger side lower trim and gloveboxas well if I remember in order to move the CC unit out from behind the dash.

 

I bought my CC unit brand new from GBM parts in Kings Lyne for

[Steve S.]

Well, I've had a reply from this company in the USA...Auto&Truck Electronics in Florida.They will for $99 repair your c/c module or bench test it for $55. shipping is a mighty $39. there is a 3 year guarantee. All of which makes it cheaper than

[mrchipz]

Hi all,

 

I have a '96 tdi with the 90hp 1Z engine.

My cruise keeps cutting out after a short time.

I also notice it cuts out at the same spots on a local road.

Typically its as the car goes into dip and 'overspeeds' slightly. On the way out of the dip and the cruise is no longer on.

Pressing resume sometimes works, sometimes resume won't work until back on the level.

I was wondering if there is anything between the switches (pedal and control) and the ecu. Maybe a relay or something that senses momentumthat maybe faulty.

 

Can somebody please help.

 

Thanks in advance

[mk2vr6]

flooding the board wont get your question answered any quicker!

[NikpV]

Hi all,

 

I have a '96 tdi with the 90hp 1Z engine.

My cruise keeps cutting out after a short time.

I also notice it cuts out at the same spots on a local road.

Typically its as the car goes into dip and 'overspeeds' slightly. On the way out of the dip and the cruise is no longer on.

Pressing resume sometimes works, sometimes resume won't work until back on the level.

I was wondering if there is anything between the switches (pedal and control) and the ecu. Maybe a relay or something that senses momentumthat maybe faulty.

 

Can somebody please help.

 

Thanks in advance

 

 

wonder if you have a dodgy brake/clutch switch - goes over a particular bump and it kicks it out, wont resume if it thinks the brakes/clutch switch is activated

[big_kev]

Hi all,

 

I have a '96 tdi with the 90hp 1Z engine.

My cruise keeps cutting out after a short time.

I also notice it cuts out at the same spots on a local road.

Typically its as the car goes into dip and 'overspeeds' slightly. On the way out of the dip and the cruise is no longer on.

Pressing resume sometimes works, sometimes resume won't work until back on the level.

I was wondering if there is anything between the switches (pedal and control) and the ecu. Maybe a relay or something that senses momentumthat maybe faulty.

 

Can somebody please help.

 

Thanks in advance

 

I would think that the likely culprit would be either the brake or clutch switches ( assuming you have a manual gearbox ).

 

If either of these are dodgy.....which is extremely common...then the cruise control system would think that one of the pedals had been pressed and would disengage.

 

Might just be enough movement on them when coming out of a dip for them to be affected.

 

Reasonably cheap to replace....smart money would be on the brake switch .

 

 

 

Just noticed nik beat me to it... :lol:

Edited October 13, 2007 by big_kev

[NikpV]

Just noticed nik beat me to it... :lol:

 

 

:lol: :lol: :lol: :lol: :16:

[mrchipz]

Thanks guys.

Sorry about the flooding.

 

Already replaced the pedal switches and also had them disconnected and shorted the connector on the end of the wires.

Still have the same problem even with that. Runs for a short while then cuts out when it likes. Can drive on a rough road and it can be ok for a short time but then could cut out on a smooth road with no bumps etc (hard to find! lol).

I have also checked the wires running in the indicator stalk. A couple of wires have a slight crack in the insulation but didn't 'seem' to have any copper breakage. Could this area be causing the problem?

I have also dismantled the switch itself and thoroughly cleaned it out. All seemed ok in there to.

The way the CC keeps cutting out leads me to believe that there may be something between the switches and the ecu (relay?).

Can anyone confirm this for me from electrical diagrams etc please.

 

Thanks in advance.

[NikpV]

throttle position potentiometer? AFAIK there are 2 if their outputs dont match then it causes problem which may affect the cruise control

[big_kev]

throttle position potentiometer? AFAIK there are 2 if their outputs dont match then it causes problem which may affect the cruise control

 

Is this the same as the Diesel Demand Pedal Sensor ?