NAXJA Forums -::- North American XJ Association  

Go Back   NAXJA Forums -::- North American XJ Association > NAXJA Unibody Jeep Technical Forums > Jeep Cherokee XJ (1984 - 2001) > OEM Tech Discussion
HOME Member FAQ Sponsor Info Rules Bylaws E-Mail

OEM Tech Discussion Forum for OEM (Original Equipment) or stock XJs and MJs.

Reply
 
Thread Tools Display Modes
  #1  
Old February 6th, 2013, 16:50
dirtyjerseyjeep dirtyjerseyjeep is offline
NAXJA Forum User
 
Join Date: Dec 2009
Location: new jersey
Posts: 30
Oil pressure sending unit ground

Can anyone tell me where the ground is for my oil pressure sending unit ,I'm having issues with my oil pressure and I have a feeling it's working cause it's a new sending unit and my motor runs great.
Reply With Quote
  #2  
Old February 6th, 2013, 19:17
ParadiseXJ's Avatar
ParadiseXJ ParadiseXJ is offline
NAXJA Forum User
 
Join Date: Mar 2006
Location: Paradise, CA 95969
Posts: 2,774
Re: Oil pressure sending unit ground

It would be most helpful if you would include the year, engine, driveline information in ALL of your posts.

It makes a HUGE difference if you have an 89 or a 98. If you don;t include this info, you'll find it difficult to get any answers.
Reply With Quote
  #3  
Old February 6th, 2013, 19:18
kastein's Avatar
kastein kastein is offline
NAXJA Member
 
Join Date: Jul 2009
Location: Longbranch WA / Central MA
Posts: 14,235
Re: Oil pressure sending unit ground

Agreed... it's very significant especially on this question. Some years ground through the block/threaded tip on the sender, some ground through the wiring harness.
__________________
My yard looks like Sanford & Sons.
Current crapcan fleet: LS swapped bobbed 79 J10 Honcho, 4x4 auto 4.0 8.25 swapped metric ton 88 MJ
CTeunuch: Sometimes I really wonder if this sport makes you insane, or it just attracts the mentally unstable.
Reply With Quote
  #4  
Old February 6th, 2013, 19:46
dirtyjerseyjeep dirtyjerseyjeep is offline
NAXJA Forum User
 
Join Date: Dec 2009
Location: new jersey
Posts: 30
Re: Oil pressure sending unit ground

Sorry I meant to 99 xj 4.0, aw4
Reply With Quote
  #5  
Old February 6th, 2013, 20:00
ParadiseXJ's Avatar
ParadiseXJ ParadiseXJ is offline
NAXJA Forum User
 
Join Date: Mar 2006
Location: Paradise, CA 95969
Posts: 2,774
Re: Oil pressure sending unit ground

Thanks for the info.

I'm not very well versed on post-Renix era Jeeps, but since your sending unit grounds thru the harness, the harness grounds are, for the most part, grounded at the oil dipstick mounting bolt. There is a cluster of common grounds there with a terminal ring. Sometimes the connection there can become loose, corroded or both. Funny that that one spot has so much to do with so many components and it's in about the dirtiest spot on the engine.

Clean the area up, remove the bolt, shine everything up and fix any loose or corroded connections...tighten it all up. It's likely that if you're having gauge issues that the sender is toast.

On the Renix models, the sender is just a one wire, grounds thru the block and when the sender goes south it usually pegs out past 80psi or goes to zero.

On a side note: You can go to User CP and fill in the info on your Jeep in your signature, then it pops up in every post you make.
Reply With Quote
  #6  
Old February 6th, 2013, 21:00
dirtyjerseyjeep dirtyjerseyjeep is offline
NAXJA Forum User
 
Join Date: Dec 2009
Location: new jersey
Posts: 30
Re: Oil pressure sending unit ground

Terminal ring??
Reply With Quote
  #7  
Old February 6th, 2013, 21:08
dirtyjerseyjeep dirtyjerseyjeep is offline
NAXJA Forum User
 
Join Date: Dec 2009
Location: new jersey
Posts: 30
Re: Oil pressure sending unit ground

My oil pressure gauge acts up, I've replaced my nss and it still won't work. I think I have a ground issue.
Reply With Quote
  #8  
Old February 6th, 2013, 22:15
kastein's Avatar
kastein kastein is offline
NAXJA Member
 
Join Date: Jul 2009
Location: Longbranch WA / Central MA
Posts: 14,235
Re: Oil pressure sending unit ground

I don't recall exactly where your gauge grounds, but it's definitely through the harness on a 99. Since those senders rarely go bad (the one wire resistive ones are much more prone to failure), I would suspect a ground issue as well.
__________________
My yard looks like Sanford & Sons.
Current crapcan fleet: LS swapped bobbed 79 J10 Honcho, 4x4 auto 4.0 8.25 swapped metric ton 88 MJ
CTeunuch: Sometimes I really wonder if this sport makes you insane, or it just attracts the mentally unstable.
Reply With Quote
  #9  
Old February 7th, 2013, 07:34
Sidewinder CC's Avatar
Sidewinder CC Sidewinder CC is offline
NAXJA Forum User
 
Join Date: Jul 2010
Location: Canton, Michigan
Posts: 1,022
Re: Oil pressure sending unit ground

Your '99 oil pressure sensor grounds through the PCM. It's a typical sensor used on your '99 XJ, in that it has a 5 VDC reference voltage supplied by the PCM, a sensor signal to the PCM, and a sensor ground to the PCM.

This sensor ground circuit is spliced into the ground circuit for the TPS, IAT, ECT, CPS, MAP, and others - all terminating inside the PCM.

If you are having oil pressure problems I would suggest checking the oil pressure using a mechanic's diagnostic direct reading oil pressure gauge. These can be rented (money back) from O'reilly and Advance auto parts.
Reply With Quote
  #10  
Old February 7th, 2013, 12:16
mnoeltne mnoeltne is offline
NAXJA Forum User
 
Join Date: Jun 2008
Location: Grantsville, UT
Posts: 82
Re: Oil pressure sending unit ground

Quote:
Originally Posted by Sidewinder CC View Post
Your '99 oil pressure sensor grounds through the PCM. It's a typical sensor used on your '99 XJ, in that it has a 5 VDC reference voltage supplied by the PCM, a sensor signal to the PCM, and a sensor ground to the PCM.

This sensor ground circuit is spliced into the ground circuit for the TPS, IAT, ECT, CPS, MAP, and others - all terminating inside the PCM.

If you are having oil pressure problems I would suggest checking the oil pressure using a mechanic's diagnostic direct reading oil pressure gauge. These can be rented (money back) from O'reilly and Advance auto parts.
I would check the oil pressure with a mechanical gauge as Sidewinder says above. It will at least eliminate that as the source of your problem.

Since your sensor grounds through the wiring harness, I would pull the plug and clean the contacts on both the sensor and the plug, then trace the wire as far as you can, preferably all the way to the PCM, making sure there is no damage to the wire. Also check that the crimps at the plugs are in good shape as that can lead to faulty readings.
Reply With Quote
  #11  
Old February 7th, 2013, 13:15
dirtyjerseyjeep dirtyjerseyjeep is offline
NAXJA Forum User
 
Join Date: Dec 2009
Location: new jersey
Posts: 30
Re: Oil pressure sending unit ground

Okay, thanks guys much appreciated
Reply With Quote
  #12  
Old February 7th, 2013, 13:27
kastein's Avatar
kastein kastein is offline
NAXJA Member
 
Join Date: Jul 2009
Location: Longbranch WA / Central MA
Posts: 14,235
Re: Oil pressure sending unit ground

I'd probably start by unplugging that harness connector from the ECU and measuring from the ground pin on the ECU end to the ground pin on the oil sender end, then check for shorts from that whole wire to the chassis. No need to tear into the harness until you know you have an issue.
__________________
My yard looks like Sanford & Sons.
Current crapcan fleet: LS swapped bobbed 79 J10 Honcho, 4x4 auto 4.0 8.25 swapped metric ton 88 MJ
CTeunuch: Sometimes I really wonder if this sport makes you insane, or it just attracts the mentally unstable.
Reply With Quote
  #13  
Old February 7th, 2013, 14:04
Sidewinder CC's Avatar
Sidewinder CC Sidewinder CC is offline
NAXJA Forum User
 
Join Date: Jul 2010
Location: Canton, Michigan
Posts: 1,022
Re: Oil pressure sending unit ground

I think the OP just asked about the ground for the oil pressure sensor since there's so much chatter about grounds relating to the XJ's, not really knowing if he had a ground fault.

It should be known just what oil pressure problems the OP has before suggesting chasing ground wires.
Reply With Quote
  #14  
Old February 7th, 2013, 18:34
dirtyjerseyjeep dirtyjerseyjeep is offline
NAXJA Forum User
 
Join Date: Dec 2009
Location: new jersey
Posts: 30
Re: Oil pressure sending unit ground

Oil pressure is great till it warms up then after its at temp, oil pressure drops to 20 as I'm driving and zero when I stop, motor runs great no Power loss at all, no knocks, Ticks or taps. Sending unit is new from advanced auto.
Reply With Quote
  #15  
Old February 7th, 2013, 20:13
Sidewinder CC's Avatar
Sidewinder CC Sidewinder CC is offline
NAXJA Forum User
 
Join Date: Jul 2010
Location: Canton, Michigan
Posts: 1,022
Re: Oil pressure sending unit ground

Quote:
Originally Posted by dirtyjerseyjeep View Post
Oil pressure is great till it warms up then after its at temp, oil pressure drops to 20 as I'm driving and zero when I stop, motor runs great no Power loss at all, no knocks, Ticks or taps. Sending unit is new from advanced auto.
Let us know the results of the direct reading oil pressure gauge tests.
Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Oil Pressure Sending Unit Turncoat_Reno OEM Tech Discussion 5 May 7th, 2012 12:05
Oil Pressure Sending Unit mfascuba OEM Tech Discussion 7 September 5th, 2010 20:02
Oil Pressure Sending Unit leaks out back of unit? mramr1974 OEM Tech Discussion 3 March 25th, 2008 03:44
Oil pressure sending unit Akumachan Wanted: Private Party Only 1 January 7th, 2007 10:01
Oil Pressure Sending Unit krizgawd OEM Tech Discussion 10 February 3rd, 2006 00:41


All times are GMT -7. The time now is 02:46.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
NAXJA and NAXJA logo's Copyright NAXJA. All content/images Copyright NAXJA 1999-2014