406 Cruise Control stops after a few minutes. Not brake pedal switch

The car is a 1997 406 - 4 cylinder petrol engined auto purchased new,
now done 270,000 km without any serious issues and no previous
problems with cruise control.

Almost all operation of the car has been on motorway under cruise
control.

When started from cold, (daytime temperature 20 degrees Celsius)
cruise control can be engaged normally but will invariably stop
operating after 3 to 4 minutes (less if the temperature is higher) and
can not be restarted immediately.

If I continue driving at motorway speed limit of 100 kph occasionally
attempting to restart cruise, I usually succeed after about 30 minutes
but operation will stop after only 1 to 2 minutes.

When daytime temperatures exceed 30 degrees Celsius, cruise will not
work at all.

I have driven the car this way in the two weeks since the problem
first appeared and have found it to be quite predictable, i.e. it
never operates longer than about 4 minutes, might be restarted after a
half hours spell but will then only run for a minute or two and will
not operate at all when hot.

Car spent most of yesterday with Peugeot dealer who replaced brake
pedal switch and steering column cruise control switch as well as
checking all the wiring. None of this has had any effect, the problem
remains. I have tested it today on the freeway and it behaves exactly
as before.

Dealer, who is not charging me for his unsuccessful repair attempt,
says I should talk to an auto electrical specialist.

I suspect the vacuum pump. Any suggestions?

 

On Sat, 17 Feb 2007 05:50:36 GMT, Bob Morrison

The problem turned out to be an intermittent open circuit in the
vacuum release solenoid valve(part of an assembly in the engine bay
consisting of the vacuum pump and this dud sol. valve in a plastic
bag).
I was quoted $AUS 1,000 for the complete assembly plus installation as
valve not sold separtely.
Opeated on the faulty valve re-soldering dry joint(s) at coil ends and
everything is working fine.