95 Accord with the cruise control intermittently shutting off.

I have a 95 Accord 2 door with automatic transmission 157,000 miles
appr. At infrequent intervals, after I set the cruise, it will engage
and then will drop out as if the brake was pushed or thr cruise was
shut off. The cruise on off switch light remains lit. The check engine
light is not lit. If I push the set button a couple of times the
cruise will engage and I will not have any problems for a couple of
days. I have a factory manual and went through the trouble shooting
list for this item and it did not have anything specific to this kind
of problem. I have worked on some Toyota's and their cruise is
interconnected to the brake master clyinder oil level. If the level is
too low, the cruise will not kick in and there will be no indication
what the reason is. I did not see a reference to this in my Accord
manual and my brake fluid level is to the top line. The manual also
indicates that a defective brake switch may be an issue. Using a VOM I
checked the action of the brake switch and it seems normal. The switch
is also not on the ragged edge of activation so that is probably not
the cause. Any suggestions as to where to look?

 

That was my first guess.

Did you check both pairs of contacts? They're probably using a set of
normally-closed contacts in parallel with the normally-open contacts that
power the brake lamps. That NC pair might not be making a perfect
connection. All it takes is a little vibration as you're driving to open
them which disables the cruise control.

Don't you like intermittent problems? Unfortunately there is no way to look
inside the cruise control unit and determine _why_ it is turning off. In
addition to the brake switch some Hondas (like my Prelude) also monitor the
shift position switch, the ignition coil and the speed sensor. If it begins
to drive you crazy you might hook up some kind of voltage-monitoring alarm
logic circuit. If [cruise control main switch = ON] and [brake lights =
OFF] and [brake switch to cruise control unit = OFF] then [set latch and
sound alarm].

Of course, looking at the schematic for my car that would still trip every
time you apply the brakes. The cruise control NC contacts probably open
slightly before the lamp normally-open contacts close.

I would also check each of the ground connections involved in the cruise
control.

You might do a preemptive replacement of the brake light switch.

 

To verify that the shift switch is not the problem, wiggle the shift control
lever while driving with the cruise control active. The cruise control
shouldn't turn off until you move the lever to another gear setting.