Cruise control problem

bigred

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New to forum. Have a 99 3.8l V6 convertible in Ohio. Cruise is driving me nuts!
So far I've checked the buttons on the wheel and have power to them, plus I took off the cover of the on/off buttons and horn honks when both are pressed. Have changed the servo and the brake pedal switch, all fuses are fine but still nothing.
The only thing I can think of left is the VSS on the automatic trans but my speedometer and odometer work fine and no shifting problems with the automatic. I've had it for 2 years and it just decided to stop working. Doubt if it's the Clock spring either as my horn will work no matter which position it's in. Cable from servo to throttle body is fine also.
Any ideas would be a great help!
Thanks, Al
 

lwarrior1016

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Well, unfortunately I’ve never troubleshot one of these systems. If you find someone with a good scan tool, you can monitor the commanded and achieved state of the cruise control. Make sure the ecu is seeing the demand for cruise. The cruise module might be bad.
 
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bigred

bigred

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Thanks, there is so much to these it's unreal!
Where the heck is the cruise module?
Plus I'd like to know if it's possible for the output sensor to be bad and still have speedometer working but not the cruise. I've tried finding that but no luck.
 
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bigred

bigred

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Yes if you're talking about if I have brake lights. No bulbs out either. I probably replaced two things that were fine.
I see the module that iwarrior was talking about I call the servo , that's one of the things that's been replaced. I'm lost, this is a mystery..lol
 
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bigred

bigred

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Yes if you're talking about if I have brake lights. No bulbs out either. I probably replaced two things that were fine.
I see the module that iwarrior was talking about I call the servo , that's one of the things that's been replaced. I'm lost, this is a mystery..lol
No keds either.
 

ttocs

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Isn't there some aspect of vacuum that is used in it? I never messed with mine but I thought there was plastic ball in the drivers fender that kept at vac that was used in some manner and if the lines to it are bad it will not work?
 

cobrajeff96

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Auto or manual car?

I know on my 96 the CC module / servo are one unit and they are located in the driver fender splash area behind the wheel or just in front of the firewall. There should not be any vacuum connections to it as it's all electronic. You should be able to disconnect its harness and probe the ground pin for continuity to either chassis or neg battery cable and that ensures it at least has a complete circuit. Also you might probe its 12vdc pin to the appropriate fuse to make sure its even powering on. Power/ground is everything, without it you have nothing.
 
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bigred

bigred

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Isn't there some aspect of vacuum that is used in it? I never messed with mine but I thought there was plastic ball in the drivers fender that kept at vac that was used in some manner and if the lines to it are bad it will not work?
No this is all electric . I guess some years they are vacuum but not this one. The servo or module is in the driver's side fender well though
 
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bigred

bigred

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Auto or manual car?

I know on my 96 the CC module / servo are one unit and they are located in the driver fender splash area behind the wheel or just in front of the firewall. There should not be any vacuum connections to it as it's all electronic. You should be able to disconnect its harness and probe the ground pin for continuity to either chassis or neg battery cable and that ensures it at least has a complete circuit. Also you might probe its 12vdc pin to the appropriate fuse to make sure its even powering on. Power/ground is everything, without it you have nothing.
Yes it's in the fender well and no as many times I've been in there I never checked that.
I did check all the fuses for power with the key on and found number 35 was the only one that did not have power to it and have no idea where the power comes from, can't get to the top or back of the box. That also has shift interlock, abs which it doesn't have and engine controls on that fuse, but no power to it unless it has to be running but I wouldn't think so, that has me stumped! Could you run a jumper wire from 17 fuse same amps and hot in run to 35 or would that blow a fuse?
 

ttocs

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most of the fuses under the dash get their power from the larger fuses under the hood. Check them out
 
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bigred

bigred

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Those are all fine and there except for the spot where if it had it the abs. The spot is there but no metal contacts for a fuse there. It worked before just like it is but not sure if fuse 35 under dash had power to it before or not. 17 fuse says same thing, servo, shift lock actuator.
 
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bigred

bigred

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#35 also has PCM but so does #6 under hood plus instrument cluster but it's good. Go figure.
 

ttocs

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that fuse could have been for the lights, it would only show power with the lights on if you didn't try them. I don't have a 98 manual myself, only 94/95
 
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bigred

bigred

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#6 under hood as all of those have over 12v. #35 with lights on has .09v without ignition on.
 
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bigred

bigred

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I don't have a 99 manual but have cruise wiring diagram and printout of all fuses and relays.
 
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bigred

bigred

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Well I have ground at the servo but no power with the key on. Maybe the on button on the steering wheel would have to be pushed for power to show up, not sure myself. But that wouldn't make any sense otherwise it would work.
 

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