[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]

Re: Cruise Ctrl and Horn prob on '85 4KCSQ

Alex Kowalski (audial@aol.com) (Law Guest Account) wrote:

> Mike Watz wrote:
> >When the outside temp is cold...the cruise control...slowly drops
> after
> > settting the speed...Once the car warms up and/or the outside temp
> > warms, it works fine.
> It sounds like the vacuum is bleeding off when it's cold.  Maybe the
> pie-pan diaphragm that opens the throttle is getting tired.  Take off
> the
> hose at the back when the rubber is cold, push the diaphragm in, plug
> the
> port and and see if it will hold its position against the throttle
> return
> springs.  If it's holding there, it's leaking someplace else: the
> vacuum lines,
> possibly the brake/clutch vacuum dump switches, or the pump itself.
> As for the horns, it could be the relay in the fuse/relay panel.
> Best Wishes,
> Alex

   I've recently (past 2 months) seen 3 4000's, all with split vaccuum
hoses in the cruise control circuit.  By all means, check the servo as
Alex has suggested... but also check ALL of the vaccuum lines (servo to
tee 1, tee 1 to pump, tee 1 to tee 2 near pedals, tee 2 to clutch pedal
switch, tee 2 to brake pedal switch,) and the clutch and brake pedal
switches.  All of these must hold vaccuum for the pump to accurately
control the servo.

I probably shouldn't tell you this, but I can't resist-- The cruise
control will work fine, and properly disengage when you depress the
brake or clutch pedals, even if the first vaccuum tee is plugged or
removed (vaccuum switches eliminated from circuit.)  The switches on the
pedals operate as electrical switches AND vaccuum switches, and so long
as they function electrically, will trigger the control unit to let up.
Driving the car under cruise control witout both vaccuum and electrical
cutout is dangerous-- don't try it.  (If one of the switches doesn't
work right electrically, the engine will rev sky high when you step on
the clutch, or not slow down when you apply the brake!)  Fix the vaccuum
leak and be done with it.

Horns fail often due to road salt and embedded dirt-- wire each "note"
individually to the battery  to test them.  Polarity matters! (brown is
ground.)  If the horns work, check that the ring on the back of the
steering wheel is in proper contact with the spring loaded terminal in
the column, then, by all means, check the relay as Alex has suggested.
(Look at the schematic screened on the case of the relay, then bridge
the terminals in the fuse box that normally connect to the load-- if the
horn works, wiring to the horn is good.  Hook a volt meter up to the two
terminals that power the coil and try the horn switch-- if you get
battery voltage, the wiring to the relay is good and the relay itself is

Good luck.

Eric "The Manicured Mechanic" Maxon
Chicago, IL