Speedo and Cruise problems

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tombo_ontario

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So recently I noticed that the speedo needle will "bounce" a little when I'm on the highway and go over a bump or whatever, but will steady out once the road gets smooth. It also goes down to 0 a little erradically when I come to a stop..nothing too crazy just seems a little abnormal to me. Also, I tried the cruise control the other day and realized it wasn't working, though it had been a few weeks ago when I tried last. The cruise control indicator light comes on in the instrument cluster, just does not engage when I press the set button.

My question is, would these two things be related?

from what Ive researched so far, the cruise control can be affected by

1) a vacuum leak...but I have checked and I THINK all the lines are good (but could be wrong) ...

2) it could be the speed sensor on the differential

3) the cruise control cable coming loose

I checked the cable when I got home today and saw that it was still attached though seemed to be "loose", though I don't know what it should be like, or if it is supposed to be a little loose anyways.

I believe if it was (2) then a loose connector could be causing the "bounce" of the speedo?? It's dark out now so I can't check it out until tomorrow but I'm just wondering if there is anything else I should check....thanks
 

yellocoyote

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Most likely #2. Either the sensor itself, or the wiring leading to it. My KJ seems to eat the wiring every couple of years - it's never been the sensor. It's gotten to the point where I now carry extra pigtail sections in the jeep to replace the worn ones when they are rubbed bare.
 

jeepguy4276

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I agree that #2 is most likely the problem. The sensors do go bad but it's usually a wiring issue. Even if the wiring looks good, it probably isn't. It's the wiring that come out of the underbody under the bake seat on the driver's side. If the wires aren't moved the same problem will happen again. I got new wire and started it right where the original wiring comes out. I ran it along the driver's side along near the brake lines. Then I turned and followed the rear wiring that goes tho the fuel tank etc. then ran down to the axle and to the sensor. I used a thin layer of electrical tape over the whole run of new wires and than a layer of cloth electrical friction tape like what they are wrapped in from the factory. Than I ran a fiber reinforeced waterproof tape over it. I made sure there was enough wire to allow plenty of suspension drop without tugging the wiring. When i was satisfied it wasn't going to rub on anything zip tied it and used wiring mounts in places to keep it in place. I put the new sensor in and took the opportunity to change out fluid in the diff. The wiring and new sensor took about an hour to do as I tried a few ways to run it. I think it would take 1/2 hour or less to just rewire and put the new sensor in. It's a pretty easy job.
 

tombo_ontario

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thanks guys for the input/suggestions. I'll take a look tonight and maybe do what Jeepguy4276 said. I have to change the diff fluid anyways so might as well do it at the same time. I'll post back when/if I get it sorted out.
 

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