91 owners manual/Cruise control

[CDegner]

Does anyone have one? I understand that there is a good diagnostics section for the cruise control in there. Mine does not work after having some brake work done. I haven't been able to find out. Of course, where I did not find out it did not work for quite some time after I had the work done so the place I had the work done says tough.



Would anyone be willing to scan the pages that cover the diagnostic procedures and send them to me at carl20320@adelphia.net. I would GREATLY appreciate it.



Also, if anyone has any input on where to start, I would like to hear it. Fuse and switches in the steering wheel are good. Been looking for loose connectors but all seem to be in order. Brake switch is OK too.



Carl

 

[BushWakr - RIP]

I have the 93 manual and here is what is shows if the cruise control does not engage when "set/decel" is selected...



1) Fuse blown

2) No vacuum at servo

3) Speed control throttle cable disconnected

4) Improper stop lamp and speed control switch adjustment

5) Faulty electrical circuit **(see appropriate section of service manual)

6) Defective servo

7) defective vacuum pump



Well, that's a place to start at least...



bob.

 

[CDegner]

Thanks for the info. I just sat down with the wiring diagrams for a good long time and tomorrow I will be checking a few more potential trouble spots



Carl

 

[TSuter]

Wasn't sure how much of a difference there was between the '91 and '93 manuals so I checked my '91 and it reads exactly as what BushWakr sent you. I don't have a scanner but if you need anything else I'll see if I can scrounge one up somewhere and send you the info.



Tom

 

[cotto]

I had the same issue. Fortunately the owner before me added an electric trailer brake module below the steering column, so when the brake pedal is pressed the LED lights up (which shows that the brakes are engaging, brake lights are on, and cruise is disengaged). I notice that bumps in the road jogged the brake pedal just enough to move the brake light switch to illuminate the LED and my brake lights (also disengaging the cruise control, if it would let the cruise control engage at all). So after a little lookin around under the dash I noticed the switch (which should not move) had actually been moved back. The plastic threads, that are suppose to keep the switch housing immobilized, are worthless. A light pull up on the brake pedal and the switch housing will dislodge backwards inturn expanding the distance between the neutral brake pedal and the switch. This distance would break the cruise control circuit. If I push the plastic switch box forward just a hair everything works as it should (until my foot accidentally bumps it and dislodges it again). This is a long story to say that when you had your brakes done, they might have moved your pedal in a negative direction and moved your switch just enough to irritate you. The switch might look right and work alright for your brakes, but it might be keeping your cruise from working b/c the cruise thinks you are applying your brakes. If there looks like there is a little play, try pushing the switch housing toward the arm of the brake pedal. Then give your cruise another shot. I didn't notice if you had an auto or manual trans. If it is a manual you might want to check the switch on you clutch pedal as well. I finally got my cruise control to engage, but now I just can't get it to hold my flippin' speed. Keep us posted. Good luck.



Cotto

 

[CDegner]

Brake switch

I have tested this switch thoroughly. Unfortunately, it seems to be working flawlessly. I to have had the problem in the past of it getting pushed back. The way I found the problem is my brake lights were staying on. Since it does happen on occasion, I have made it a habit to check the taillights when I get out of the truck.



If a couple vacuum checks do not turn anything up, looks like it will be in to a mechanic. I hate to find out what that will cost! :--)

 

[paccool]

I'm glad to finally see someone else talk about the brake light switch. I have commented several times that I had problems with the cruise control that were caused from the switch but several guys basically said that it was something else.

My problems also started after doing some brake work. It turned out to be the adjustable rod between the booster and the master cylinder was out of adjustment and the pedel arm was not making good contact against the switch. Adjusted the rod but still had a problem now and then. Replaced the switch, was ok for awhile then started again.



What I found was that I was hitting the peddle with my right foot as I got out of the truck and this was pushing the brakelight switch up a little. The switch just pushes in so there is not a good way to hold it in position. I ended up putting a cable tie around the switch and this has stopped the problem. Someone else (can't remember who it was) was able to get a push nut to fit and that also held it in place.

The trailer brake light is a good indication, I watch mine to make sure the brake lights are not coming on. I also have ran the battery down as the switch came on and the lights stayed on when I parked. Once the neighbor came over and told me they were on.



BTW - the switch can also cause an erratic operation of the cruise control. Will surge sometimes and not work at all other times.