2000 GMC Yukon Fuel Gauge not reading

LAUNCH10

MEMBER
2000 GMC YUKON

Electrical problem
2000 GMC Yukon V8 Two Wheel Drive Automatic

The fuel gauge constantly reads empty with the low fuel warning words in info box. The fuel unit in the tank is New. I used the best wiring diagram I could find(Clilton's, and online AutoZone.) The Purple (ppl) wire has 5 volts reference with key on and I connected a jumper directly to the Org/black(org/blk) wire and still reads empty. I need help on what to do next. The wiring diagrams are in conflict one saids go to the ECM other go to BCM. Which one and which wire? Is it still the org/blk to check?
Help
Thanks

5 Replies

RACEFAN966

MECHANIC
5,029 POSTS

Ok you need to disconnect the harness to the sender and use a panel tester that allows you to set the ohms of resistance from 40 to 240 ohms to see if the guage is working and do this between the dark blue wire and the orange and black wire. With 40 ohms of resistance it should read near empty and at 240 ohms resistance it should read near full. If you dont have the proper tool see if you can have a local electrical repair shop do this test for you. If the guage works then it has to be in the sending unit.

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Monday, December 1st, 2008 AT 11:23 AM

LAUNCH10

MEMBER
5 POSTS

I used a DVOM tested old fuel sender were the pump went bad but fuel gauge was still reading correctly. I put it in the 40-240 ohms range. However the fuel gauge was still pegged past empty(not on E) below it.
I traced the org/blk wire to the ECM under hood. Reading of 1 ohms so good connection from Fuel sender to ECM. Buy the way only have one fuel pump so the other wire is PURPLE not dark blue. I am getting the 5volts reference on the PURPLE wire.
Thanks
what next?

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Tuesday, December 2nd, 2008 AT 10:28 AM

RACEFAN966

MECHANIC
5,029 POSTS

Ok you need to be able to supply resistance this can not be done with a digital multi meter it is a completly different tool that will actually control the guage so you see if the guage in the dash is working. If your wire is purple then it is purple according to the wiring diagram it should be purple on s-10 models and dk blue on yukons anyway this is why I said you may want an electrical tech to do this test as they will probably have the tool.

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Tuesday, December 2nd, 2008 AT 10:39 AM

LAUNCH10

MEMBER
5 POSTS

I don't want to fuss over this matter. First, I did not use the DVOM to do the test. I was just making reference that I tested the Old Sender out of another GM vehicle to confirm it was in range. 40-240 ohms. Second, the vehicle 2000 Yukon XL 5.3L was made in Mexico and the wiring harness to this vehicle has Black(Ground), Gray(12v from relay for Fuel Pump)/org/blk(Fuel sender return)PPL(5volt reference). That is all going to the fuel pump and sender. My book shows the dk blu for the 6.0L, SUV. But anyway I would like you help to find out what wire coded color runs behind the instrument cluster for the Fuel Gauge so I see if the Cluster gauge is defective. Let me tell you your help is greatly appreciated. Thanks

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Wednesday, December 3rd, 2008 AT 10:13 AM

RACEFAN966