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Cruise Control - works great - but how to adjust sensitivity?

H

HAPYMUDY

NAXJA Forum User
Location
Western New York
Put the 32" tires on the Cherokee this past week and all's well. With the new gearing dynamics, the cruise control tends to be a little too sensitive for my liking.

Is there a way to adjust it so that it is not quite so sensitive? For example, if I set the cruise to 70, going up a hill if it were to dip to 68, rather than downshift and try to stay exactly at 70, I'd be okay with it.

I know, picky-picky, but when you are cruising comfortably, the sudden downshift and engine racing takes away from the cruise-ness.
 
I had the same problem, especially when I was driving x-country and going through Iowa or some other state with tons of rolling hills. The cool thing was that after I put in my cat back system by Dynomax, the problem pretty much went away. It seems like that just gave it enough torque to keep at 70 without down shifting on hills.
 
Renix XJs cruise sensitivity can be adjusted by the yellow box under the dash below the steering wheel... I've never messed with mine so I couldn't tell you exactly how to do it.
 
Those old cruise control boxes have three adjustment screws that are labelled...

Low Cut - adjusts the lowest speed at which the system can be engaged

Centering - adjusts how much the speed can deviate from the setting +/- mph.

Sensitivity - adjusts how quickly the speed servo reacts to maintain speed control

HAPYMUDY, it sounds like you want to back off the centering control just a touch to allow a bit of "sag" on hills. If you play with the sensitivity you clould end up making it take too long to resume a set speed or the other way trying to throw you into the back seat when it decides to floor it to make adjustments.
 
xzalt said:
I have the same problem with my 95, could I make the same adustments to the yellow box?
Click to expand...

Yep, I was referring to the yellow/purple/grey box systems used on a lot of XJs. The system was made by Hayes/Dana and I have personally installed a shiteload of them. The adjustments I talked about in my first post will work on any of those systems...be careful, set it incorrectly and it can surprise you!
 
Last edited:
xzalt said:
I have the same problem with my 95, could I make the same adustments to the yellow box?
Click to expand...

Do you have a yellow box in your '95? I installed the OEM unit in mine, and it consisted of the buttons in the steering wheel plus the vacuum actuator under the hood.
 
Cruise??? you have cruise!

jeeze, mr. fancy xj......bigger lift, tires, and now this...... <jeep envy>


Did you change out your speedo gear yet? Figure out which one it needs, I have a few in my tool box... you never know.
 
Ah, but you got the cool blue XJ ... not positive what speedogear swap I will need.

Original tires were 225s (27" diameter)
Goodyear MTR 32s = 31" diameter (go figure!)
 
Back from the grave with an old thread....


I have the same question, but my Jeep is a 1994 - there's no little yellow box.

Is there any way to make these adjustments?

Thanks.
 
You guys do realise the reason the cruse goes nuts is because you added larger tires without regearing right? What is happening is the computer tries to compensate by just giving extra throttle, and because of the larger tires it the moter can't exert as much force as it should. Basicly it thinks the hill is larger or you're carrying more weight. The ony way to correct it compleatly is to regear. Just changing the speedo gear might help a little, but wont cure it.
 
On the Renix setup, yes you can adjust the settings on the yellow box. On the later HO engines, the Chrysler PCM controls the servos and there is no way to adjust it.
 
scoobyxj said:
You guys do realise the reason the cruse goes nuts is because you added larger tires without regearing right? What is happening is the computer tries to compensate by just giving extra throttle, and because of the larger tires it the moter can't exert as much force as it should. Basicly it thinks the hill is larger or you're carrying more weight. The ony way to correct it compleatly is to regear. Just changing the speedo gear might help a little, but wont cure it.
Click to expand...
x1000
 
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