how do you know its the computer? - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep Grand Cherokee & Commander Forums > ZJ Grand Cherokee Forum > how do you know its the computer?

Poison Spyder DeFenders™ - "Tubeless" Jeep FendeAll Bilstein shocks & struts - Lowest Prices Ever and Santa Kolak Announces: Kolak Exhaust 20% Off Sale!

Reply
Unread 09-25-2009, 04:50 PM   #1
sweetie
Registered User
 
Join Date: Jun 2009
Location: ky
Posts: 7
how do you know its the computer?

Hello everyone Im back with another question!We have a 97 gjcl that has been nothing but trouble!We recently had it scanned at advance auto and it showed a bad ignition coil.So we changed that plus the gas cap(they said it was vapor locking)and a new throttle position sensor.Well its quit dieing while driving it but now its flooding.Its flashing bad coolant sensor but we just replaced that also.A mechanic that checked it thinks its the computer because the sensor is good.He said its telling the motor its 40 below zero outside!Thats why its sending more gas to the motor than necessary.Anew computer is going to be over three hundred bucks and Im about ready to just roll it over a freaking cliff at this point!Does anyone know how to check for the computer without having to pay a hundred bucks just to find out?Thanks!

sweetie is offline   Reply With Quote Quick reply to this message
Unread 09-25-2009, 05:14 PM   #2
moparrr07
Registered User
1998 ZJ 
 
Join Date: Jun 2008
Location: belvidere, Illinois
Posts: 772
ok first of all, never take advise from an auto parts store EVER, next you need to find a new mechanic,

i have run into this instance twice, throwing a coolant sensor code means there is a problem with the coolant temp sensor circuit, it could be the computer, it could be the sensor, it could be THE WIRING IN BETWEEN! also once i got a brand new coolant sensor in the box that was bad, open brand new,

you need to test the NEW sensor, the wiring between the sensor and pcm and if it is still a problem, then i would consider the pcm,

but your right when i senses cool (-40) (open circuit default) it will start pouring the fuel on causing a flood

not only that but unhooking the sensor will put in in open loop

and finally unhooking that particular sensor will put it into base timing mode, making it run like garbage,

you need to find a technician, not a mechanic, someone who actually knows what they are doing and will test it, not just through $300 parts at it to see if it fixes it
__________________
-Black Limited 1998 Jeep ZJ 5.2 nv3550 np242, 35s, lots of other stuff
moparrr07 is offline   Reply With Quote Quick reply to this message
Unread 09-26-2009, 02:36 AM   #3
Colorado 5.9
Registered User
1998 ZJ 
 
Join Date: Dec 2001
Location: Denver, Colorado
Posts: 2,049
A bad IAT senser can cause it to run ritch also.
__________________
ZJ 98 5.9 LTD. Lots of mods. 7" T&T's Long Arm Lift ,BFG KM2"s,35X12.50x16's,4:56's, Vanco brake upgrade, M1intake,Holley52mmTB,MikeLeach Headers,, Arb'ed HP D30,Aussie Locked rear,Procomp MX6 Shocks,Arb front,RearTR bumpers,ECT.ECT.

Latest Pics
Colorado 5.9 is offline   Reply With Quote Quick reply to this message
Unread 09-26-2009, 03:17 AM   #4
ratmonkey
R.I.P.
 
ratmonkey's Avatar
1997 ZJ 
 
Join Date: Dec 2006
Location: , Pennsylvania
Posts: 19,794
You're going to need an fsm to do the diagnostics, as well as a multimeter.
Check the temp sensor for continuity, make sure it reads the right resistance for the temp you have it in. Test it up to operating temps in some hot/boiling water.

Next check the wires for continuity, this is where you'll need the fsm to get the correct pins at the ecu connector.

If that is all good, and the code comes back after a comp reset. You'll need a new ecu most likely.
__________________
'97 zj 5.2, some stuff, some other suff, and some things that even work sometimes.

ratmonkey is offline   Reply With Quote Quick reply to this message
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.
Note: All free e-mails have been banned due to mis-use. (Yahoo, Gmail, Hotmail, etc.)
Don't have a non-free e-mail address? Click here for a solution: Manual Account Creation
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.


Thread Tools


Suggested Threads





Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.