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Unread 02-23-2013, 07:40 PM   #1
Shane7
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1998 ZJ 
 
Join Date: Mar 2012
Location: Lakewood, Ohio
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Cruise control not setting..

Just replaced the clock spring in my ZJ 2day and the cruise light comes on like it should again but it doesn't set. Whats the issue? Is it a fuse?

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Unread 02-23-2013, 08:07 PM   #2
ratmonkey
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either brake switch, throttle position sensor, or vacuum leak are the most likely problems.
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'97 zj 5.2, some stuff, some other suff, and some things that even work sometimes.

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Unread 02-23-2013, 08:37 PM   #3
Shane7
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Quote:
Originally Posted by ratmonkey View Post
either brake switch, throttle position sensor, or vacuum leak are the most likely problems.
definetly not a vacuum leak, I checked all the seals. Any other suggestrions?
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Unread 02-23-2013, 09:04 PM   #4
AVR2
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As ratmonkey says, brake switch or TPS. To which I would add, faulty cruise servo or even PCM issues.

As well as checking for vacuum leaks, did you ensure that there's definitely enough vacuum at the servo? I think the minimum level is 9 mm/Hg, but you'd have to check the 1998 FSM to be sure.
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Unread 02-24-2013, 04:27 AM   #5
KoreaZJ
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Reseat brake lamp switch connector.

Brake lamp switch might be out of adjustment...
  1. Push/hold brake pedal down.
  2. Pull switch plunger all the way out. (pulls hard and makes ratcheting type sound when it comes out)
  3. Release brake pedal. (should rest against the switch plunger)
  4. Pull brake pedal fully rearward firmly to reset switch position. (makes ratcheting sound when it goes in)
(Brake lamp switch has three separate circuit contacts. Just because the brake lamps work doesn't mean the cruise switch contacts are working)


Brake lamp switch might be bad. Unplug the connector, test the switch continuity between Pins #3 and #4 with meter while actuating the switch.




Cruise switches may not all be working properly. Measure resistance between clock spring connector Pins #1 and #2






Servo testing...

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Unread 02-25-2013, 03:06 PM   #6
Shane7
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Quote:
Originally Posted by KoreaZJ View Post
Reseat brake lamp switch connector.

Brake lamp switch might be out of adjustment...
  1. Push/hold brake pedal down.
  2. Pull switch plunger all the way out. (pulls hard and makes ratcheting type sound when it comes out)
  3. Release brake pedal. (should rest against the switch plunger)
  4. Pull brake pedal fully rearward firmly to reset switch position. (makes ratcheting sound when it goes in)
(Brake lamp switch has three separate circuit contacts. Just because the brake lamps work doesn't mean the cruise switch contacts are working)


Brake lamp switch might be bad. Unplug the connector, test the switch continuity between Pins #3 and #4 with meter while actuating the switch.




Cruise switches may not all be working properly. Measure resistance between clock spring connector Pins #1 and #2






Servo testing...



Hm, it now makes sense to me why it would be the switch. I tried thisand still had no luck, so now it leads me to believe I need a new one all together. thanks!
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Unread 02-26-2013, 03:43 PM   #7
Shane7
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Well I tired both resetting and replacing the brake light switch and still no luck. /: I really don't think it could be a vacuum leak but if it is, where should I look and how can I fix it?
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Unread 02-26-2013, 03:50 PM   #8
PolkaPower
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Cruise control thingy is on the passenger side above the fuse box. The plastic hose from it may be broken somewhere.

(edit)I see you have the 4.0. Well here is a useless picture then.
picture-5.jpg  
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Unread 02-26-2013, 04:00 PM   #9
Shane7
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Quote:
Originally Posted by PolkaPower View Post
Cruise control thingy is on the passenger side above the fuse box. The plastic hose from it may be broken somewhere.

(edit)I see you have the 4.0. Well here is a useless picture then.
Hahah! Yeah, I forgot to mention I had the 4.0. My mistake! Thanks, anyway!
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Unread 04-02-2013, 10:43 PM   #10
Shane7
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So, for awhile I gave up on this, but I am now kind of curious about it. Still comes on, but refuses to set. I replaced the brake switch and I'd think that if it was a vacuum leak it would throw the check engine light on, am I right?
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Unread 04-02-2013, 11:02 PM   #11
KoreaZJ
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Did the resistance measurements for all the switches check out good according to the chart?
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Unread 04-02-2013, 11:58 PM   #12
AVR2
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Quote:
Originally Posted by Shane7 View Post
I'd think that if it was a vacuum leak it would throw the check engine light on, am I right?
Most vacuum leaks won't cause a CEL.

First thing, measure the vacuum at the cruise servo and confirm that it's within spec. The magic number is in the FSM; for the 1993 ZJ the minimum acceptable vacuum at the cruise servo is 10 inches of mercury. It's probably the same for yours, but maybe not.

If that's OK, then the remaining options are (according to the troubleshooting flowchart in the FSM):

Cruise control throttle cable disconnected
Improper stop lamp and speed control switch adjustment
Faulty electrical circuit
Defective servo
Defective vacuum reservoir
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