Hi all, my DII has developed a fault with the cruise control. It sets ok, resets ok, but when engaged the speed very slowly drops. If I set it at 70,
5 minutes later it's dropped to 60! There are no other indications or fault codes and physically the system appears ok. Anyone got any clues, or came across this one before? Ta, Badger.Brian Hi,
Vacuum loss springs to mind first if the cruise control on D2 vehicles operates like that.
I would start with the hoses supplying vacuum and then would check the "bomb" itself.
HTH
Take care Pantelis
Yep, slow loss of vacuum. Check all pipes and joints. BTDT, etc.
DII isn't a vacuum type system, it appears to be a form of electric actuator controlling a secondary throttle cable. Am starting to think it may be an issue with connections at the steering wheel.... anyone know if it has slip-rings and carbon brushes? Badger.
Fully electronic on the TD5 you don't say what fuel you use... B-)
Other option is a faulty, out of calibration or simply gunged up sensor for the secondary throttle cable position. Cruise control can't just lock the throttle at a fixed postion it has to constantly adjust it just as one would when driving manually up/down hills. The system has to "know" where the throttle is. I don't know that such a senor exists mind...
Right, I made a mistake. There is an electrically operated vacuum pump which feeds the "pull" unit. No position sensors, the only sensing input to the ecu is road speed. If speed = target, do nothing. If speed less than target, supply vacuum to pull unit to open throttle. If speed greater than target, reduce vacuum to close throttle. System is slugged somehow, to eliminate surging and hunting around target speed. It's a V8, by the way, I don't do disiesels! ;-) There is only the one short vacuum pipe from the pump to the pull unit, it appears ok, as does the pull unit diaphragm. Still at a loss as to what's causing it though. Badger.
From your description loss of vacuum would cause loss of speed. For a small throttle position change over several minuets it would be a tiny, tiny leak. But, in theory, the lowering road speed should increase the vacuum supply to compensate.
It could be the hysteresis control part (what controls the electric vacuum pump?) or possibly slighty sticky/stiff linkages. Does everything move freely?
Ah, of course. In that case, it'll be the *electricity* leaking out of the cables.
Fixed! I was under the mis-impression that the DII was a purely electrical system. There is indeed a vacuum pipe, albeit short, and guess what - yep, it'd perished and split! In my case, this is a classic example of "you learn something new every day"! Thanks to all who chipped in. Badger.
Result! Rich knew something that Badger didn't. A first for Usenet. More champagne, butler!
hehehe. Badger.
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