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View Full Version : Cruise control issue - already replaced TPS - any advice?



MikeyM
06-29-2005, 07:15 PM
When on the fwy, the ZJ sometimes does the typical RPM fluctuation of about 200-250 RPM when cruise is set on the highway. I replaced the TPS about a year ago but shortly after that the problem returned. Just a couple days ago, I unplugged the TPS to check the voltage reading but must have done it wrong because I didn't get any reading - will try again. But I was wondering what else could be the issue? Maybe a bad TPS from the box?? Wouldn't be the first time. Anyone know about the cruise circuit and what else could be the issue? The RPM fluctuation only happens when in CC and all else works just fine.

Thanks, Mike.

Kraqa
06-29-2005, 07:46 PM
CHECK YOUR VACCUM

MikeyM
06-29-2005, 08:06 PM
right off the manifold with a vaccuum gun when engine off or guage when engine on?

Thanks, mike.

Kraqa
06-29-2005, 08:17 PM
on

OverkillZJ
06-29-2005, 08:27 PM
When the engines off, there should be vacume held as well. Even if your rigs been sitting for a week, when you pull the line off of the actuator you should hear the air getting sucked in for a second.

nate
06-30-2005, 03:06 AM
I had my Jeep parked for 3 months and the vac canister still was holding vacumm. I thought it might be leaking... one hell of a slow leak if it was haha.

bill~ns
06-30-2005, 09:29 AM
If you've unplugged your TPS and checked for voltage, you won't find any. A sensor cannot create voltage when there's no power plugged into it. You want to check for resistance on the TPS.

Personally, I'd just throw another TPS on it... I'm on my 3rd one now of 2 years of owning the grand. Just replaced my last one last week. All problems cleared up immediately. Dealer TPSs have a 1 year warranty, so save your receipts.

Bill

MikeyM
06-30-2005, 11:51 AM
Good to know.. thanks guys. Also, I will check the vacuum.

MikeyM
07-01-2005, 04:36 PM
PS - Is there a spec? Should it be right around 20" hg?

Thanks.