I own a '83 Eldo with the 4.1L V-8, DFI & 27,750 miles and auto trans.

I can turn on the cruise control switch at the dash and get an "Orange or Amber Light", but when I try to activate the system on the steering column the "Green" Light does not come on and the cruise control does not enguage, Period. Tried from 30 MPH up to 65 MPH.

I have replaced all vacuum lines underneath hood, checked and double checked all connections. Have checked all the hoses underneath the dash and their connections along with the brake switch. Have also checked engine codes and no codes are being displayed.

I do not have a vacuum test unit.

Any suggestions?

 

By checking the brake switch, do you mean both switches on the support? One completes the circuit and also dumps vacuum when the pedal is depressed. The other supplies power to the brake lights. Are both adjusted. did you check supply voltage with a test light? Do you have a factory service manual? Thru on board diagnostics, you can do a switch test of the cruise system. Try this, While driving above 35 MPH, put your foot under the brake pedal and lift up hard and hold your foot, then set the cruise. Does it work, does the green light illuminate? If so, the brake switch or switches are out of adjustment or one is faulty.

 

OK, I have figured out the switch system for the brake light and the cruise control.

I can not keep the switch adjusted properly. I have taken the ring that the switch goes through and made
the edges a little sharper in order to hold the switch in place. At this moment, I can not get the switch to stay in place up against the brake pedal stem.

Do they make an after market switch that has real threads? Have you ever encountered this situation and do you have any other suggestions.

Your input has been of great help.

Again, thank you for your input.

Equalizer in Big Sky

 

What wears is the plastic switch. So replace the switch. They are available in the aftermarket. Which one wont hold, vacuum dump switch or brake lamp switch? To adjust, you simply push the switch toward the pedal till the plunger bottoms, then with foot under pedal, pull back gently till the ratcheting adjustment noise quits.

 

Again, thank you for your input. The Vacuum switch is the one that will not hold. Have fooled and fooled with it an can not get it to stay one more ring out.

In all this fooling around I have also been trying to work out a long and hard brake pedal.

One question, which may or may not be related to all this. On Friday, I was helped change out the Brake Power Booster. After that was changed out we fooled with the two switches (brake light & vacuum dump) We could not keep the vacuum dump switch in place for the cruise to work, however, the Brake Power Booster helped the brake pedal situation a lot. I then drove the car around town just to make sure everything worked properly. I put on about 20 miles without any problems. This mourning my wife takes the '83 into Church early to help an elderly lady get to Church and I go in a different vehicle.

After about 5 miles of driving, I get a call stating the car will not go another inch and something stinks. Yes, the brakes or one of the brakes had locked up. When I arrived you could smell the burning brake pads. My question? Could I have done something wrong in changing out the Power Booster to make the brakes lock up? After the car cooled off, (brakes cooled off) I got in the car and drove it without any problem back into town. I have no idea what happened, but my wife is not real impressed with my abilities. Any thoughts??

Equalizer

 

Yes you could have. The booster has a threaded shaft exiting the back that attaches to the brake pedal. You probably do not have enough clearance or " freeplay" on this rod, allowing the master cylinder to partially depress the brakes. Or I've seen brake light switches that keep the pedal itself depressed ever so slightly. Usually tho the brake lights stay on as well. The attaching clevis that hooks to the brake pedal more than likely rotated upon installation, shortening the rod length. The switches are designed to "slip" within the metal ring to fine tune the depth of the switch to the pedal.

 

By the way, have the rear calipers been adjusted and/or replaced to correct the long pedal and lack of parking brake?

 

Answer to last question. Yes, rear Calipers have been adjusted. The parking brake will now hold in a stopped position when you put the car into gear. My wife still complains the brake pedal is too hard to push and still too much pedal travel.

I removed the master cylinder from the Power Boost and measured the rod against the rod in the old Power Boost. Both exactly the same, down to 100th of an inch. I had put some grease on the rod/piston when I exchanged the Power Booster. I have now cleaned all the grease off of the rod/piston, thinking that perhaps was the cause of the brakes locking up. Today the brakes locked up within 500 feet of where they locked up the first time. So, the car is setting along side the road and in the A.M. I will drive it back into town and take it to the shop and start looking at the other side of the power booster, i.e. where it connects to the brake pedal.

RE: Cruise Control. I have that fixed!!! I purchased a coarse threaded "Nut" and had enough room in front of the bracket to force thread it onto the switch so that it will not back out of the holder. One Problem down. Again, I appreciate your input and help.

Back to the Brakes. If I get everything adjusted properly, i.e. to specks and I still have long pedal travel and wife complaining about hard to push, should I look at different calipers???. I can not afford these high priced after market set ups that have more pistons, i.e. 2 or 4 as I think the calipers that came standard with the '83 had one piston. Could I look at a later model cadillac brake & rotor set-up that would produce better stopping power. I have not had any replys from my last post on the brake issue.

Thank you,

Equalizer

 

These cars with the brakes working correctly do have a somewhat long pedal travel because 4 wheel disc brakes do not self energize like drum brakes do. Its very important to have the right surface on the rotor, not glazed, and the correct pads. If the rear calipers needed adjustment then most likely the rotor surface is glazed from prior lack of use.I would resurface the rear rotors and either rough up the pads or replace with Delco brand new to improve the feel. Regarding the booster, I think you're on the right track in checking the rod length to the pedal. Also make sure the attachment to the pedal is not in any kind of bind (the retaining clip) and make doubley sure the dump switch is not pressing on the pedal not allowing to fully come to rest, foot off pedal. Did you adjust the rear calipers with the parking brake cables disconnected from the caliper levers? as the manual dictates.

 

Reporting in. It appears I have the Power Boost and the Locking up problems resolved. 1. The power boost was purchased from NAPA and the rod on back side of the unit was not adjustable. I ended up purchasing 2 washers from local hardware store, approx. thickness 56 thousands, and placing them between the Booster and Master Cylinder. Have driven over 50 miles and no problems. The brake travel and pressure on the brake pedal is about the same, perhaps 5% less.

I have taken the car back to the local garage, who did the initial work on the brakes and asked them if the rear calipers were adjusted with the parking brake cable disconnected and he said yes!!! He also inspected all 4 rotors and pulled pads from passenger side front and rear, they are not GM Pads, but NAPA pads purchased last year. They looked very good.

It was suggested I consider and install a "Residual Pressure Valve" on each line. I have done a little research and have a general idea of their concept or how they should work. What are your thoughts??

Again, I really appreciate your input.