Trouble with oil pressure gauge (1 Viewer)

[melepley]

I've recently (well about eight months ago) purchased a 1998 LX470. I've been lurking around this forum and found several very useful threads, Thanks for all the help! I now have an issue that I haven't been able to find any information pertaining to my exact problem. I have an issue with my oil pressure gauge staying at zero.

I had done some maintenance work on my LX, wheel bearing repack and ignition coil replacement. After finishing I started the engine and noticed the oil pressure sitting on zero, no other lights on the dash are lit. I verified I actually have oil pressure then went to work troubleshooting the gauge issue. I checked the engine compartment where I had worked for loose wires and saw none. Next, I looked in the service manual for troubleshooting steps and used those found on pages BE-87 and 88.

1. I disconnected the oil sending unit and checked the gauge still read zero.
2. I grounded the lead from the sending unit through a test light to see if the test light lights up with the ignition on and if the gauge goes to high.
   1. The light lit but the gauge stayed on zero.
3. I pulled the cluster and ohm tested the oil pressure gauge, it had the required resistance.
   1. 160 ohms was the spec, I had 165 ohms on both, seemed close enough.

I have not done the sending unit test because I have to make the LED tester plus the sending unit was replaced in December 2016.

Anyone have any idea what could be wrong?

Thanks

 

[Jeepster09]

unstable oil pressure gauge

 

[melepley]

I really appreciate the link! The thread indicates the sending unit could be bad (again) and I can't dispute that however, wouldn't the test with the test light have made the gauge read high if it was just the sending unit?

 

[bigredmachine]

check your connectors for corrosion could also be part of the issue

 

[melepley]

I appreciate all the assistance. The link provided by Jeepster09 was helpful. To perform the last test of the sensor from the fsm required I get a LED and make a test light from it. After making this I was able to test the sensor and I found it was shorted to ground. This caused the gauge to remain at the low position on the gauge. I replaced the sender and now the gauge is working as expected.