cruise control no worky- what to check?

[fastr68]

my 91 pickup cruise control does nothing

all hoses and wiring connectors are good and connected and fine

cannot find anything wrong

it doesnt set or accelerate or anything

what do i need to check and how ?

thanks for anything

[Dr.Fiero]

Did you check the adjustment on all the switches? If it's an automatic, there's just the one on the brake pedal, but...

Go straight to the module, and check for all the asst power signals it needs.
(and all the various signals it gets when you press 'set' etc)

The toughest one I've found is the servo itself - if EVERYTHING checks out OK, I usually just resort to swapping in a known good one.

[fastr68]

Quote: Originally Posted by Dr.Fiero

Did you check the adjustment on all the switches? If it's an automatic, there's just the one on the brake pedal, but...

Go straight to the module, and check for all the asst power signals it needs.
(and all the various signals it gets when you press 'set' etc)

The toughest one I've found is the servo itself - if EVERYTHING checks out OK, I usually just resort to swapping in a known good one.

hi there ok yeah its an auto trans truck, ill have to check the brake pedal switch out then

sometimes i know the switch is a dual combo switch brake and cruise together inside it and two wiring plugs on it

thisone may be also, in which case the switch should be fine because my brake lights work fine

although i notice that the overdrive TCC doesnt seem to disengage when i hit the brake pedal and cause the RPM to increase slightly

so hmmm..

thanks

[Dr.Fiero]

That era of cruise stalk was prone to breaking as well.

Where the wire goes from the stalk to the column would fatigue and crack.
So.. check that the switches all electrically work properly.

[fastr68]

haha well today i checked switches under the dash and found the cruise vacuum switch was completely broken apart

it is switch number 15600278

two wires and large vacuum hose



another question:


all the wires to the servo under the hood are dead with the key on even

shouldnt something be hot at all times especially with the ign on ?


interesting ?

thanks

[Dr.Fiero]

Quote: Originally Posted by fastr68

all the wires to the servo under the hood are dead with the key on even

shouldnt something be hot at all times especially with the ign on ?

With the key on, and the cruise switch in the on position, you should get B+ between pins "A" and "J" on the servo.

[fastr68]

ok thanks i guess i should re check for this


what does it mean if i have no b+ power there even when all the fuses are good and such?

thanks again

[Dr.Fiero]

Power goes from:
Ign/gauges fuse -> pin "A" of cruise stalk -> out of pin ""B" from cruise stalk (if it's "ON") -> grey wire goes down to the brake switch, comes right back out of the switch, then heads for pin "A" on the servo...

So, trace it through!