just about fed up - Jeep Garage - Jeep Forum

Go Back   Jeep Garage - Jeep Forum > Jeep Platform Discussion > Grand Cherokee - WJ

Reply
 
Thread Tools Display Modes
 
  #1  
Old 07-09-2015, 07:26 AM
Member
 
Join Date: Jul 2015
Posts: 13
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 731
tc862011 is on a distinguished road
just about fed up

I need your help, I bought my 2000 jeep grand Cherokee Laredo with a 4.0 with February, shortly after that I realized that for some reason someone installed a jumper wire from the fuel pump fuse to the 02 sensor fuse. the jeep runs just fine but if I take that jump out it will crank but wont start I put the jumper back in it starts right up and runs fine. I noticed if I take the jumper out and run power straight from the battery to that same o2 sensor fuse I hear the fuel pump relay click and it pressures up the fuel line. also with the vehicle off and the key out al the fuses but one have power under the hood, at the same time all this is messing with the asd relay if I shut the vehicle off quickly it stays running for 10 seconds. I have checked the wiring harness under the hood and haven't seen anything that concerns me, I have also had the fuse block out so I could look in the bottom t and all the wires and clips in there look fine not broken wires, corroded wires or burnt wires. I am getting so fed up with this and I am hoping that someone will be able to point me in a direction of a "weak" spot in the harness I should check like under the dash or something

Reply With Quote
Sponsored Links
Advertisement
 
  #2  
Old 07-09-2015, 08:06 AM
Frango100's Avatar
The beast from Brazil

My Jeep: 2004 4.7L WJ
 
Join Date: Dec 2009
Location: Brazil
Posts: 7,613
Thanks: 23
Thanked 423 Times in 408 Posts
Rep Power: 529931
Frango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond repute
Re: just about fed up

Welcome to the garage.
I presume that the problem is with fuse 24 on the junction block, isnīt it? That is at least the fuse for the fuel pump. But you say that you put power on the O2 sensor fuse and the fuel pump starts running? Best is to mention the exact fuse position # where you put the power on, to prevent mistakes.
There is no power on which fuse?
__________________
Frank

JEEP Grand Cherokee 4.7 Lmtd 2004
HID 8000K in low and fog / Quad Squad member
KYB Gas-a-Just shocks / Pirelli Scorpion ATR 245/65/17 - Transgo reprogramming shiftkit.

VW Beetle 2.0 TSI 2013
My new toy
Reply With Quote
  #3  
Old 07-09-2015, 08:18 AM
Member
 
Join Date: Jul 2015
Posts: 13
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 731
tc862011 is on a distinguished road
Re: just about fed up

I am looking at the fuse cover right now, it is the fuse block under the hood and its the 02 sensor number 16 fuse that if I put power to that one with the jumper removed I hear the fuel pump relay click and the fuel pump turn on, basically the jumper is taking power from the fuel pump fuse number 24 and supply that power to the o2 sensor fuse number 16 but the confusing part about it is that they both have there own power so why would jumping the two cause anything to happen or change and when the key is out of the vehicle there is power to all the fuses but the trans solenoid fuse number 28, sorry a lot of confusing information
Reply With Quote
Sponsored Links
Advertisement
 
  #4  
Old 07-09-2015, 08:25 AM
Frango100's Avatar
The beast from Brazil

My Jeep: 2004 4.7L WJ
 
Join Date: Dec 2009
Location: Brazil
Posts: 7,613
Thanks: 23
Thanked 423 Times in 408 Posts
Rep Power: 529931
Frango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond repute
Re: just about fed up

O2 sensors without power will not prevent the engine from running. It looks like you are back feeding the ASD circuit via the O2 fuse. I would start swapping the ASD relay with a same one in the PDC and see if that helps, because to me it looks as if an ASD relay problem was solved by using the jumper.
Also check fuse #6 in the PDC.
This also explains why the engine doesnīt go off imediately when switching ignition off, because the ASD circuit stays powered all the time and the engine only shuts off after the fuel pressure gets too low.
__________________
Frank

JEEP Grand Cherokee 4.7 Lmtd 2004
HID 8000K in low and fog / Quad Squad member
KYB Gas-a-Just shocks / Pirelli Scorpion ATR 245/65/17 - Transgo reprogramming shiftkit.

VW Beetle 2.0 TSI 2013
My new toy
Reply With Quote
  #5  
Old 07-09-2015, 08:33 AM
Member
 
Join Date: Jul 2015
Posts: 13
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 731
tc862011 is on a distinguished road
Re: just about fed up

I have put in a new relay for the asd and tried starting it without the jumper and it still would only start with the jumper in, I took a pic of it to show you but I cant figure out how to upload it, maybe cause I am a new member I don't have those privileges yet
Reply With Quote
  #6  
Old 07-09-2015, 08:35 AM
Member
 
Join Date: Jul 2015
Posts: 13
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 731
tc862011 is on a distinguished road
Re: just about fed up

im just confused on why when the o2 sensor fuse has power applied to it the fuel pump system responds
Reply With Quote
  #7  
Old 07-09-2015, 11:06 AM
Frango100's Avatar
The beast from Brazil

My Jeep: 2004 4.7L WJ
 
Join Date: Dec 2009
Location: Brazil
Posts: 7,613
Thanks: 23
Thanked 423 Times in 408 Posts
Rep Power: 529931
Frango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond repute
Re: just about fed up

Quote:
Originally Posted by tc862011 View Post
im just confused on why when the o2 sensor fuse has power applied to it the fuel pump system responds
Fuse 16 is for the O2 sensor feed, but the power comes via the ASD relay contact. For some reason the ASD relay is not closing. When you now take power from fuse 24 (which has power as long as the battery is connected), you will feed the O2 sensors, but also backfeed the PCM. The PCM can then do its job and switches the fuel pump on and all the rest its suppost to do. So for some reason the ASD relay is not doing its job. Let me see the wiring first and then i will come back to you.

---------- Post added at 01:06 PM ---------- Previous post was at 01:01 PM ----------

Did you check fuse #6 in the PDC? Its the supply for the ASD contact. It should have 12V all the time. Measure on pin 30 of the ASD relay if the 12v is present there as well. Let me know if ok sofar, then we can see how to proceed further.
__________________
Frank

JEEP Grand Cherokee 4.7 Lmtd 2004
HID 8000K in low and fog / Quad Squad member
KYB Gas-a-Just shocks / Pirelli Scorpion ATR 245/65/17 - Transgo reprogramming shiftkit.

VW Beetle 2.0 TSI 2013
My new toy
Reply With Quote
  #8  
Old 07-09-2015, 11:21 AM
Member
 
Join Date: Jul 2015
Posts: 13
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 731
tc862011 is on a distinguished road
Re: just about fed up

i will check on this stuff and get back to you, thank you so much for the help
Reply With Quote
  #9  
Old 07-09-2015, 03:14 PM
Member
 
Join Date: Jul 2015
Posts: 13
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 731
tc862011 is on a distinguished road
Re: just about fed up

I checked all that stuff and I was able to get it started with out the jumper not its not reliable I could start it 3 times and then fight it again, I think there is a connection issue but everything has power and I checked all the wires they look fine, I am about to just replace the stupid box
Reply With Quote
  #10  
Old 07-09-2015, 04:34 PM
Frango100's Avatar
The beast from Brazil

My Jeep: 2004 4.7L WJ
 
Join Date: Dec 2009
Location: Brazil
Posts: 7,613
Thanks: 23
Thanked 423 Times in 408 Posts
Rep Power: 529931
Frango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond repute
Re: just about fed up

Indeed there probably is a bad connection. I would just check the connections in the box and see if there is not something loose/broken.
Probably with checking, you moved something, whereafter the contact re-estabilized.
__________________
Frank

JEEP Grand Cherokee 4.7 Lmtd 2004
HID 8000K in low and fog / Quad Squad member
KYB Gas-a-Just shocks / Pirelli Scorpion ATR 245/65/17 - Transgo reprogramming shiftkit.

VW Beetle 2.0 TSI 2013
My new toy
Reply With Quote
  #11  
Old 07-10-2015, 06:23 AM
Frango100's Avatar
The beast from Brazil

My Jeep: 2004 4.7L WJ
 
Join Date: Dec 2009
Location: Brazil
Posts: 7,613
Thanks: 23
Thanked 423 Times in 408 Posts
Rep Power: 529931
Frango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond repute
Re: just about fed up

Eventhough the wires look fine externally, there is a change that there is an internal break, while the isolation is still intact. When you get it running again, try to mess a bit with the wires and see if the engine stops.
__________________
Frank

JEEP Grand Cherokee 4.7 Lmtd 2004
HID 8000K in low and fog / Quad Squad member
KYB Gas-a-Just shocks / Pirelli Scorpion ATR 245/65/17 - Transgo reprogramming shiftkit.

VW Beetle 2.0 TSI 2013
My new toy
Reply With Quote
  #12  
Old 07-17-2015, 07:51 AM
Member
 
Join Date: Jul 2015
Posts: 13
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 731
tc862011 is on a distinguished road
Re: just about fed up

I haven't abandoned the thread just trying to get time to actually work on it again and will pot my results when I do
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Just starting to customize my jeep, just have a few questions CjCoats1693 New Members - Welcome! 0 02-09-2015 03:28 PM
Starting to get fed up! SteveC Grand Cherokee - WK2 - 21 01-06-2014 07:36 PM
New Jeep owner already fed up w customer service jblow New Members - Welcome! 5 07-27-2013 09:34 PM
Fed up! tashakirkham Suspension/Driveline/Brakes/Wheels/Tires 8 11-22-2012 02:05 PM

» Premium Vendor Showcase
Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 05:36 AM.


Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Copyright 2012 - JeepGarage.Org
The Jeep Grand Cherokee Owners Community

JeepGarage.org is in no way associated with or endorsed by FCA US LLC. Chrysler, Dodge, Jeep, Ram, Mopar and SRT are registered trademarks of FCA US LLC.