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2003 silverado 5.3 liter oil sending unit problem

 
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bkoons bkoons
New User | Posts: 1 | Joined: 02/07
Posted: 02/10/07
03:03 PM

Oil pressure gage flips back and forth from 0 to 80 lbs. is this the sending unit going out or the oil pump. Where is the sending unit located on the engine on a 5.3 Liter. I found what to me looks like a low warning sensor on the engine right in front of the starter. I unplugged it and the gage still does the same thing.

Any help appreciated...  

miskiw miskiw
New User | Posts: 1 | Joined: 03/08
Posted: 03/03/08
07:37 PM

I have a 1995 GMC 5.7L engine. The Oil Pressure needle flips back and forth from 20 to 80 lbs. Is it safe to operate the vehicle? 260,000 km.  

jgate-#002 jgate-#002
Guru | Posts: 953 | Joined: 06/07
Posted: 03/04/08
01:00 PM

It would be safe to drive if it is only a bad oil pressure sensor. On the 5.3 and the 5.7 The sending unit is located on the left rear top of the engine, behind the intake manifold mounted into the top of the block.  

tybee69 tybee69
New User | Posts: 1 | Joined: 01/10
Posted: 01/09/10
04:32 AM

The sender is located on the back of the engine left (drivers) side. It's between the throttlebody and the firewall, and screws into the top of the block. You can remove it with a 1-1/16" deep/thin wall socket and about 1/2 pound of flesh off the top side of your right hand. Seriously if I had to do it all over again, I'd hire it done by the pros. It will not only save you a lot of heartache and pain, but a lots of knee time asking forgiveness for all the name calling, cursing, and BAD attitude.

Hope this helps, tybee69-Savannah Ga.  

Turbo Buick Turbo Buick
User | Posts: 146 | Joined: 11/05
Posted: 01/09/10
07:39 PM

Chevrolet trucks have instrument cluster problems. The cluster should be under warranty until 100,000 miles. After that prepair to spend more than $500 to get a reman cluster from GM. You can replace it with a used one from another pick-up, Escalade or Hummer (all will fit),  but beware they all will fail eventually.  

millman miller millman miller
New User | Posts: 2 | Joined: 07/13
Posted: 07/31/13
05:02 AM

Also just to inform anyone thats giong to do this repair to buy a sending unit from GM. I bought 3 aftermarket units that would not work. The sender has a 3 wire plug. one of those wires sends a signal to the fuel system saying there is oil pressure.  Some of the aftermarket ones are too sensitive and result in long engine cranking times until there is enough oil pressure for safe starting. If there is no oil pressure or it is very low, the engine with not start which is a nice little saftey feature.  

millman miller millman miller
New User | Posts: 2 | Joined: 07/13
Posted: 07/31/13
05:02 AM

Also just to inform anyone thats giong to do this repair to buy a sending unit from GM. I bought 3 aftermarket units that would not work. The sender has a 3 wire plug. one of those wires sends a signal to the fuel system saying there is oil pressure.  Some of the aftermarket ones are too sensitive and result in long engine cranking times until there is enough oil pressure for safe starting. If there is no oil pressure or it is very low, the engine with not start which is a nice little saftey feature.  

wayne712222 wayne712222
Guru | Posts: 1857 | Joined: 03/13
Posted: 07/31/13
09:20 AM

LS OIL Pressure Sender

this is where the oil pressure switch is... top of the block next to the bell housing mounting face..

warning...  if you are experiencing long cranking times.. replace the fuel pump relay and verify the relay has some resistance to removal or installation in the relay socket..

i have found many bad fuel pump relays where the contacts are dirty inside

but.. i have also found many oil pressure switches that have a bad contact for the fuel pump circuit.. on the outer terminals..  the relay is supposed to be activated by the PCM for 2 seconds when you turn the key on.. then again while cranking... if you stop cranking the relay opens..  

the oil pressure switch has 3 terminals.  the center is for the gauge..  the outer two are for the fuel pump circuit..

a HUGE HINT in long cranking diagnosis...

probe the fuel pump fuse with a test light ..

does the fuel pump fuse get power when you turn the key on without cranking the engine ??? this is just for the first 2 seconds of the key being on??? it should.

does the fuel pump fuse  get power as soon as somebody starts to crank the engine?? it should..

now that the engine is running...    reach into the relay box and pull the fuel pump relay out..   yes.. while the engine is running..  the engine if the oil pressure switch contacts for the fuel pump circuit are good.. should continue to run...

most of the current for the fuel pump circuit should run thru the oil pressure switch.

if the oil pressure switch contacts are bad.. the engine will die..  this tells you that you need to change the oil pressure switch.. as the relay will have a very short live span if the oil pressure switch is not carrying the load of the fuel pump circuit.. this can leave you stranded ..

if you don't have a test light.. you can remove the fuel pump relay and carefully remove the outer box from it to expose the inner workings on some years.. this allows you to see if the fuel pump relay is getting the proper signal from the PCM.. you can also manually squeeze the contacts closed to test that the fuel pump turns on when you do so..

most of the square fuel pump relays... can also have the spring removed and the movable contact plate slipped out of position to clean the contacts.. but the wearing away of the contacts may limit their ability to close properly..

hope this helps...  

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