: Cruise Control Issue

DopeStar 156
03-20-05, 11:31 PM
Has anyone else experienced a loss of power on inclines when using cruise control? If I have my cruise on and I go up a hill I start to lose MPH. It went as far as 45 MPH from the 65 MPH lock I had it at going uphill but if I floored the pedal it would shoot back up and go. Does anyone else have this? Is this a typical thing for this car to do since it is so heavy and it has the 307? I know there's a vacuum leak in the car but it's from the parking brake auto release which doesn't work. Are the cruise and the brake release all on the same vacuum and could that be why my car doesn't automatically accelerate going up hill with cruise on?

03-20-05, 11:48 PM
I've had that problem with my Aerostar, it is underpowered in overdrive up hills. I turn off the overdrive and it stays up to speed. In my 5.0 Mustang I have also lost cruise going up hills in 5th. I haven't had an issue in the cadi. Next time you go up a hill on cruise try dropping the tranny down into 3rd and see if that helps.

03-21-05, 12:35 AM
My 85 Cutlass 307 did the same things. I took it apart and found the seals getting hard. I cleaned them up with little improvment, and it failed soon thereafter. See your local Cadillac dealer for a new one.... :(

307 is fine on power for hill cruising, and the cruise unit will drop it out of OD if needed. The 307 is torquey for a 5.0L, 255 lb ft at around 2800 rpm. And a flat curve at that.


03-21-05, 10:17 AM
Well, if you say there's a vacuum leak but it's the parking brake release, I would take the time just to check the vacuum for the cruise. That makes a difference.


DopeStar 156
03-21-05, 08:18 PM
Can anyone tell me where the vacuum lines for the cruise control are? Are they under the hood or under the dash? When my car was last serviced a split vacuum line was found under the hood, by the carb I would assume because that's where they were working. They cut the split part off and reattached it. They told me they would guess it was for the cruise.