cruise control test

[GLS0628]

I have read multiple post regarding the cruise control and brake switch and have not seem an answer to my particular question. I have a 96 c1500 that the cruise control is not working. All of the brake lights work fine. My question is can the brake lights work fine and the brake switch still be the problem with cruise control? Or does it all work off of the same part of the switch? I have disconnected the plug to the module and tested what I have seen suggested. Pin A, B, C, F, and G all test fine so I assume that means the stalk/multi function switch is working fine. Pin D is not testing good though. My understanding is that pin D (purple wire) should give 12 volts when the brake is not pressed and then drop when the brake is pushed. I am not getting a full 12 v when the brake is not pushed but can something less than 12 volts make a difference? It is testing around 5 volts. Do you think this means it has to be in the harness from the brake switch to the plug that goes into the module? My thoughts is that the module is not picking up the brake pedal is not pushed and not allowing it to turn on.

thanks,
Greg

 

[Keepinitoldskool]

I may be wrong but i think there are 2 brake switches.

 

[someotherguy]

My question is can the brake lights work fine and the brake switch still be the problem with cruise control? Or does it all work off of the same part of the switch?

Absolutely. There are multiple contacts in the brake switch, one for each function. (Brake lights, cruise disengage, torque converter clutch disengage.)

The brake light switch is very commonly an issue with inoperative cruise. It's inexpensive and fairly easy to replace. On your '96 you may have the round style clip; it's tricky to figure out but if you spin it around on the stud you'll see where it splits there's a hole - which is really two half-holes, since the split goes through it. Use small snap ring pliers to gently spread the clip at that hole and slide it off the stud. Then the switch unhooks off the brake booster rod, slide it off the stud, and unplug it. Easy. Clip just slides back on to re-install.

Others reading: 1988-1993 use a totally different kind of switch and it's adjustable so that should be checked first. 1994-up are non-adjustable. Older trucks that don't have the round clip have a rectangular one that slides sideways a little before you can wiggle it off.

Also, prior to 1995, the most common failure is the cruise lever itself - wiring breaking internally or the contacts in the switches going bad.

Richard

 

[Keepinitoldskool]

I may be wrong but i think there are 2 brake switches.

I was wrong. I was under my dash today and there is only one. But the newer trucks have 2.

 

[Eskimomann209]

Have to ask
You have had function of your cruise before correct?
You know how to engage it?
Over 25 MPH I think is the rule hold for three or so seconds
And the little switch is in the correct direction?

 

[mattillac]

Welcome to the forum.

My question is can the brake lights work fine and the brake switch still be the problem with cruise control?

Yes, and you should have 12 volts there not 5 volts, might be time to test through the brake switch. (a double pole single throw switch) 4 wires, 2 separate circuits.

Below is how the brake switch should be wired(cruise wise);
-------------------------------------------------------------------

<Orange wire(pin B)12v in supplied via Stop/Haz Fuse(20A)#1 IP block
S
W
I
T
C
H
<White wire(pin A)12V out to cruise module/brake applied input(pin G)


<Brown wire (pin F)12V in supplied via Brake Fuse(10A)#18 IP block
S
W
I
T
C
H
<Purple wire (pin C)12V out to cruise module/disengage input (pin D)

--------------------------------------------------------------------

Check the Brown and Purple wire at the brake switch. Brown is 12V in and Purple is 12V out, for the disengage input. That 12 volts should pass through the switch when the pedal is at rest(key in run position).

Ignore the orange and white wire at the brake switch, that part(one pole/circuit)of the switch is working, right.

Best wishes.

 

[GLS0628]

yes it only stopped working 3 or 4 months ago. until then everything was fine. since all of the functions at the stalk tested good I am going to focus on the brake switch now. I am thinking that the switch is not letting it come on.

 

[GLS0628]

You lost me a little on last post but I think that I did what you suggested already and tested at the female part of the plug that I disconnected at the cruise control module (on the firewall). I tested what i think was pin D (cavity or female end not the pin side) and did not have power with the key on. I think that I read this should have power when brake pedal not pushed and loose power once brake is pushed. Is that correct? With the functions from the stalk all testing good, is it safe to say that is not the problem?