help with a oil sender problem

[w ogden]

OK guys, a little off track here but I have been helping a friend with a 01 Grand Cherokee with a V8 that has no oil presssure. Turns out it is elelctrical it seems as we have put a mechanical guage in and it is carrying oil pressure. The dash guage starts out at 60 and then goes to 0 and stays there. Could be wiring? WE have replaced the OP sender already of course and it did not help. Any ideas or if you have a wiring diaghram it would be great. Thanks Walt

 

[Ronnie Russell]

Walt, My 2002 Dodge P/U has been doing that for 4 years. Same symptom as you describe. I turn the radio volume up when the check-engine alarm starts sounding. Will be watching suggestions and maybe even fix mine someday.

 

[oldskydog]

Does the indicator use a stepper motor? If so then maybe it is having the same type of failure the 2003-2005 Chevy trucks have had.

 

[Phil Reed]

Does the indicator use a stepper motor?

For those in Texas Cecil........they will need to know if it's a 2 step or a 3 step!!!!!!!! Might even be a Cotton Eyed Joe!!!!!!!!

 

[MRHP]

Do you still have at least 15 psi at idle when hot on the mechanical gauge? I would think the sending unit is bad, but I have seen also that the oil pump pick-up screen getting plugged and restricting oil flow causing a loss of pressure. If you are sure it is not a mechanical problem, I would think the sending unit is defective. Make sure the parts house gave you the correct sender. Tell them you have a gauge, and not an idiot light. It will take different senders.

 

[Stick62]

OK guys, a little off track here but I have been helping a friend with a 01 Grand Cherokee with a V8 that has no oil presssure. Turns out it is elelctrical it seems as we have put a mechanical guage in and it is carrying oil pressure. The dash guage starts out at 60 and then goes to 0 and stays there. Could be wiring? WE have replaced the OP sender already of course and it did not help. Any ideas or if you have a wiring diaghram it would be great. Thanks Walt

Sounds like it could possibly be a bad ground if the sender is OK

 

[rstreet]

Walt: I've got to support Cecil's and "Stick62's" suggestions on this one. Seen both of them.
robert

 

[rwagon57]

Walt,

Since the mechanical gage indicates oil pressure and you have replaced the electric sender my thoughts second Stick62 and Cecil in that order. Verify you have a good and reliable ground, then if that is good (doesn't change with temperature, heater operation, etc.), then check the stepper motor in the gage.

 

[Brian Thompson]

Here are the wiring diagrams for the oil pressure circuit as per Mitchell OnDemand. Let me know if you need anything else.

http://bthompsontx.homeserver.com/2001 Jeep PCM Wiring1.pdf

http://bthompsontx.homeserver.com/2001 Jeep PCM Wiring2.pdf

http://bthompsontx.homeserver.com/Dodge Oil Sending Unit.pdf

 

[w ogden]

Thanks guys for the input and thanks Brian for the wiring diaghrams. Brian, looks like the third or last reference is for a Dodge. Did you intend to send this or did you think you were sending a description on the Cherokee? Or was this for Ronnie?
We have now changed the sender twice and same problem exists. If you step on the gas the oil guage dies and causes the alarm to sound. Great for driving but we are now following ronnies suggestion and have turned up the radio! Simple but it sure works. While the guage dies on acceleration the mechanical guage stays steady so I don't believe we have a engine issue. I'm going with the ground issue for now mostly because I don't know how to determine if I have a two step or three step motor
So I'll let you know what we find................guess we will be tracing wires for a little while

 

[Brian Thompson]

Walt-

The third link is more for information on how the sender works. It will be the same for your jeep.