cruise control or lack of it

Hi.
Anyone know if the cruise control light on the dash is part of the circut ie if the bulb goes the cruise control wont work?
Thanks
Jules

I suspect not, but the easiest way to check is to take a working bulb from an adjacent switch so you can eliminate it as a possibility.

I'm trying to fix my cruise also. Have checked the vacuum bulb and the vacuum lines and no cracks apparent anywhere; the vacuum on the bulb is holding fine. My switch light does come on. Anyone have any ideas of where to look next?

Thanks

Hi if a bulb blows it may disconnect the circuit as some manufactures use it a ground for the system.

Also you could check the servo valves and the vacuum release valve and the air valve (if fitted)

After that it's a full electronic diagnosis by a mechanic equipped with the necessary diagnosis equipment.

The only Cruise control I've had dealings with was the Volvo 740 series

Charlotte

There is a large forum at Motorcarsltd.com (hosted out of Houston, TX). There I remember reading that another cause for lack of cruise control is a switch that is apparently (if I remember correctly) actuated by the brake pedal. Someone there suggested to check the lines for cracks/leaks or this switch, as "the electricals seldom fail", or something to that effect. He mentioned that in order to check this switch one has to remove the lower fascia? to access it. I too don't have cruise control on my truck, but haven't had the time to go looking under the dash.
Hope this helps.

Yes, I found the switch on the brake pedal (it's the lower of the two, with a single vacuum line coming off it). Tested it with a multimeter and it delivers 12V when the panel switch is on and the plunger is depressed to close the circuit. So the current's getting to the switch correctly. Now I'm looking what to do next. Does anyone know how the switches are wired from the steering wheel or whether there is a test I can do (whilst stationary) on all the vacuum lines?

OK, I think I've found the problem. A 9 pin female multiplug with 6
active pins is dangling disconnected. It's under the steering wheel and
I can't see what it plugs into.
Looking at the main circuit diagrams for 1990 model year RR, it seems
certain that it's for the cruise control. The available cable doesn't
seem long enough to get behind the instrument binnacle; though the
wires have been previously bound up so it might reach.


Does it plug in there somewhere, picking up info from the speedo etc?


Thanks


Paul 1990 US Spec RR V8 EFI LPG

Hi there should be a socket for it to connect into, don't believe the Cruise Control would be located on the Speedo unit, less its a square plug (Bit like a Computer ribbon cable) then it's possible because there are two square sockets on the Speedo/Instrument panel. It may pick up from behind the accelerator pedal

Other wise it might be worth taking the dash out and seeing if the socket end has dropped behind the dash (As so often previous owners have a problem with something so instead of taking it to the Dealership or Garage they just disconnect it) I'm finding this with my 89 Range Rover SE Vogue EFi.

Charlotte

Don't know anything about your "dangling Cable" but there is a cruise control cassette behind the steering wheel nut that has a copper spring fitted to allow contact top remain when wheel is turned. I believe that this spring has a habit of breaking on older vehicles in which case a new cassette board is required.

Frank

Thanks Frank & Charlotte. Yes, I trust the cassette is ok - my first task is to plug the connector back where it belongs. I'd rather not take off the whole dash to find out where that is.

Does anyone have a good picture of the back of the instrument binnacle? The workshop manual only has a diagram and isn't at all clear. If anyone has an instrument binnacle out in the open would they mind telling me if there's a socket that looks like it would meet this:



Or maybe this plugs into the cassette somewhere??

Cheers

Paul

1990 RR County (Vogue SE US Spec) V8 3.9 LPG

Well, I've got a little further. It doesn't plug in to the back of the steering wheel and it doesn't plug into the back of the speedo. Where on earth does this thing go ?!

PualV8,

Bit of a long shot but on UK cars the cruise control won't work unless both the Brakelight bulbs are working.

Might be worth checking that?

Tom