: Cruise Control Problem



DopeStar 156
07-13-09, 08:44 PM
It started the other day when I was on my way to work, my '89 Fleetwood Brougham seems to have an issue with the Cruise Control. On the highway when you engage the Cruise it works for a few seconds then the power goes out on the system and it shuts down. The amber light letting you know it's on and the green light letting you know it's engaged both go out then after a few seconds. Then a few seconds later the amber one comes back on and the Cruise can be reengaged only to fail all over again. I've noticed that going downhill the Cruise works normally only until you level off or hit an incline. Any thoughts on what I need to do to fix this? I'm a big Cruise Control user and feel lost without it on highways....

bicentennialcadillac
07-13-09, 11:38 PM
First, check your vacuum lines.

DopeStar 156
07-14-09, 12:43 AM
First, check your vacuum lines.

That's what I was thinking because it's throttle related. How many lines go to this thing? The 307 is a jungle of vacuum lines......

sven914
07-14-09, 01:10 AM
The lights going out is electrical. My OEM Manual has a diagnostic section that leads through three diagnostic charts, which end in the replacement of the Cruise Control module and mention nothing about vacuum leaks causing the problem. I would acquire the OEM factory manual (from eBay (http://shop.ebay.com/items/__1989-Cadillac-brougham-service-manual?_nkw=1989+Cadillac+brougham+service+manual+&_cqr=true&_nkwusc=service+manual&_rdc=1)) and diagnose the problem. Also it may seem throttle related because the cruise control module recalculates the vehicle speed every time it changes, and may be malfunctioning as it does.

My car has vacuum issues to the cruise control servo, to the point where it will not even engage on flat pavement, and not once have the lights ever gone out on my switch (I have unsuccessfully been trying to find an replace the snakes that control it and drive with it on to see if I finally fixed it).

DopeStar 156
07-14-09, 01:17 AM
The lights going out is electrical. My OEM Manual has a diagnostic section that leads through three diagnostic charts, which end in the replacement of the Cruise Control module and mention nothing about vacuum leaks causing the problem. I would acquire the OEM factory manual (from eBay (http://shop.ebay.com/items/__1989-Cadillac-brougham-service-manual?_nkw=1989+Cadillac+brougham+service+manual+&_cqr=true&_nkwusc=service+manual&_rdc=1)) and diagnose the problem. Also it may seem throttle related because the cruise control module recalculates the vehicle speed every time it changes, and may be malfunctioning as it does.

My car has vacuum issues to the cruise control servo, to the point where it will not even engage on flat pavement, and not once have the lights ever gone out on my switch (I have unsuccessfully been trying to find an replace the snakes that control it and drive with it on to see if I finally fixed it).

I actually have the FSM for the car and I found the diagnostic chart pretty hard to follow. Nothing back there seemed to describe my problem but if replacing that module. Now for the million dollar question, where do I find a replacement? Is that something I can get from AutoZone or whatever or do I have to go junkyard shopping and gamble on a few?

sven914
07-14-09, 01:27 AM
PG 8A-34-3, Result 2: Cruise on indicator not lit with cruise control switch on.

If you can follow it, and it leads you to a new module, try finding an authorized AC Delco dealer (Advance Auto sells AC Delco, but they probably wouldn't stock something as vague as a CC control module). Might get lucky in the junkyard, or you can find a Brougham on Craigslist, for 500, and offer the guy 20 for the controller.

DopeStar 156
07-14-09, 01:33 AM
I looked it up and it seems easy enough to remove. Apparently you have to take the radio out and it's to the left mounted to a bracket in the dash. You don't think there could be some kinda corrosion on the connector or is it definately shot? I was thinking vacuum leak because it seemed like the system was doing some sort of emergency power down because of a leak under throttle or something. I mentioned AutoZone because I work for them so I could get it discounted from there if they had it.....

sven914
07-14-09, 01:56 AM
There is nothing definite about anything. The only way to tell exactly what is wrong is to follow the diagnostic charts. The problem could be as simple as a shorted wire. Example: (A3) if you test the module connector cavities with an DVOM and get 0 volts, the book directs you to test C2, which has you test a connector cavity to chassis ground. If the result of the test is you getting more than .03 ohms, you replace one black wire and the system is fixed and fully operational. Saying that if one, easily solved, possible cause is entirely ruled out, then the problem absolutely must be this anonymous electronic box, is how repair projects get expensive and frustrations mount.

Corrosion at the connector could cause your issue, and if there is some, clean it off an see if it fixed anything.

DopeStar 156
07-14-09, 09:52 PM
There is nothing definite about anything. The only way to tell exactly what is wrong is to follow the diagnostic charts. The problem could be as simple as a shorted wire. Example: (A3) if you test the module connector cavities with an DVOM and get 0 volts, the book directs you to test C2, which has you test a connector cavity to chassis ground. If the result of the test is you getting more than .03 ohms, you replace one black wire and the system is fixed and fully operational. Saying that if one, easily solved, possible cause is entirely ruled out, then the problem absolutely must be this anonymous electronic box, is how repair projects get expensive and frustrations mount.

Corrosion at the connector could cause your issue, and if there is some, clean it off an see if it fixed anything.

Thanks. I'll probably go in there tomorrow since I've got the day off. Worst case scenario I can get one from work by a company called CarDone for $80. I called Cadillac, discontinued......