2004 Jeep Grand Cherokee Cruise Control

Tiny
EPSJCARLSON01
  • MEMBER
  • 2004 JEEP GRAND CHEROKEE
  • 4.0L
  • V6
  • 4WD
  • AUTOMATIC
  • 111,200 MILES
My cruise control on my 2004 Jeep Grand Cherokee (4.0L) has recently stopped working. When I push the on/off button the cruise control light comes on in the dash, but when I go to set the speed it will not engage and the "cruise" light will turn off. I know the system is run of a vacuum and have already replace the vacuum servo and cable connected to the throttle body, and have inspected the vacuum lines for cracks but did not find any. Is there anything else that would cause the cruise control to not work.
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Thursday, January 29th, 2015 AT 1:49 PM

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Tiny
CARADIODOC
  • EXPERT
Yup. But you need a scanner to see why. Chrysler's scanners display the "reason for last cutout". That's the reason why the cruise control turned off intentionally, but the same causes can be used to figure out why it doesn't work when it should. For example, if it says, "brakes applied", you'd look at a misadjusted brake light switch. If it says, "road speed too low" but you were going over 35 mph, you'd look at the signals coming off the speed sensors.
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Thursday, January 29th, 2015 AT 2:20 PM
Tiny
EPSJCARLSON01
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So their is no way I can fix my issue without taking it into a shop?
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Thursday, January 29th, 2015 AT 3:02 PM
Tiny
CARADIODOC
  • EXPERT
At the risk of sounding sarcastic, (not intended), buy a scanner. I have Chrysler's DRB3 but that might be out-dated for your vehicle. A lot of independent shops bought them because with an additional plug-in card, they will do emissions-related stuff on all brands of vehicles sold in the U.S, '96 and newer. I DO know the '04 Durango was the first year the DRB3 didn't work because all cars were switching over to the new "CANN BUSS" system which is the standard now. The DRB3 worked on some vehicles up to the 2007 or 2008 model year, but only on a few models. If yours requires the newer "Star Scan", I've never used one of those.

I have five Chrysler vehicles that all used the older DRB2, but I have plug-in cards for my DRB3 that lets it work on models all the way back to '83 models. My friend has a Snapon scanner that works on more models up to 2014, but those aftermarket scanners always don't do quite as much as the manufacturer's equipment, but in some cases, they have more troubleshooting procedures built in. That way you don't have to dig out a service manual. You might check around among friends to see if someone has a scanner they can use to see if the cruise control is listed. As I mentioned, the DRB3 will display the "reason for last cutout". The aftermarket scanners I've used don't show that but they do show "switch state" that can provide clues. For example, if it lists the brake switch as "applied" when you're not pressing the brake pedal, suspect it's out of adjustment or has a bad contact. There can be three separate switches built into the brake light switch so you can't go by whether or not the brake lights are staying on.

Genesis, (might be spelled wrong), is another popular aftermarket scanner, and anything will be less expensive than Snapon products. Be aware too there's a cost to update scanners every year, and Snapon really rakes their customers over the coals for that. That's why I won't own any of their products. You can find DRB3s, Star Scans, and the aftermarket scanners on eBay. You'll be shocked when you see what repair shops have to pay to buy new equipment every year and keep it up to date, but if you plan on doing your own diagnostics, a scanner is a good investment. If you keep your vehicle for a few years and this is the only one you use the scanner on, you don't have to pay to have it updated all the time. Be aware too though, if you DO want to update it, most manufacturers simply sell you the latest update which will include everything that came before it. Snapon is famous for insisting you have to buy the updates from every year. You can't skip a year to save money. That means if it was last updated in 2010, now you have to pay for the 2011, 2012, 2013, and 2014 updates, at around $1000.00 per year, before the 2015 update can be installed. I can't say for sure if that's true, but I've heard it from a few friends who won't buy their products anymore.

If you're on friendly terms with a local repair shop, you might be able to have them diagnose the problem, then repair it yourself. There are some pitfalls to that too though. Typically the diagnosis makes up 95 percent of the labor charge for this type of problem, and the part and labor to replace it makes up the other five percent, so it pays to just let them do the entire job, and if they find out they diagnosed it incorrectly, it's their problem, not yours.

You can also ask at some auto parts stores if they have a scanner to rent. A lot of stores are renting or borrowing tools now. What you DON'T want is a simple code reader that they use to read codes for free. Those almost always can only access Engine Computers. On Chrysler products the cruise control system is incorporated into the Engine Computer, but it's very likely there will not be a fault code set for this problem. Going back to that brake light switch, if it has a pitted contact for the cruise control circuit, it will be "open" as in turned off, which it does when the pedal is pressed. While that is a defect in the switch, an open circuit is a normal condition and the computer will simply see that as the brake pedal is pressed. No fault code will be set for what appears to be a normal condition.

I am really disgusted with the severe over-use of unnecessary computers on today's vehicles, and it's why my daily driver is a rusty trusty '88 Grand Caravan. It's true the computers detect the majority of problem causes which aids diagnosis, but they wouldn't be that hard to diagnose if it weren't for those computers. My '80 Volare has cruise control, and it doesn't need a computer. Now that you DO have all these computers, consider buying a scanner. There are a real lot of things you can't do without one and you'll be amazed at what you CAN do with one.
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Thursday, January 29th, 2015 AT 5:27 PM

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