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'97 DeVille Fuel gauge


Seanmannino

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Hi all, so I have been having issues with the fuel gauge on my car. It is constantly reading full and I know it's not. The other night, I ran out of gas... :( Sad day I know. But I am not sure what would cause this to read full all the time. It does dip down every now and again. But I need to know if I can fix it or if I have to replace the fuel pump to get it to read right. Or is there a sequence I can run to make this thing work right? I know the fuel pump was replaced shortly after I bought it back in 2009 But I've never noticed it being wrong all the time until the other night when I ran out of gas. Anything I can do?

Thank you all!

Sean M.

1997 Cadillac DeVille

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There are basically 3 components to a fuel gauge. The sending unit in the tank. The wiring to the instrument cluster and the gauge display.

The sending unit is a variable resistor with a float attached to it.sometimes the additives in gas and gum from old gas sitting in the car plug up the resistor bar. I've heard of people having luck using Techron for 2 consecutive tanks will clean up the sending unit. I've never tried so can't say. The unit is part of the pump assembly. If your good with a multi meter you can access the pump and remove it, set meter to ohms and test the output while moving the float. If its bad you can replace the pump assembly to fix it. If its good I don't think wiring is bad because I think (but not sure) that an open for circuit would show empty.

If wiring is good and has continuity to the gauge then that only leaves the gauge. There are a few places that can fix instrument clusters online. Or if your handy you can get parts to repair. Or get a salvage yard cluster. If going that route you can switch out guts to the fuel gauge because if you switch clusters the odometer will not be correc . It'll show miles from the vehicle it was removed from. And if you sell car with out disclosing not actual mileage that's a big criminal charge.

Good luck.

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If you change your instrument cluster, you need to take the old and new cluster to a facility that can transfer all the data from the old one to the new one. The cluster has the VIN and option list of the car as well as the mileage, and the car just won't work unless you do that.

However, the Techroline is probably your fix. A bad instrument cluster is rare.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Thanks cadillacJim. Good to know about the clusters needing programmed. For Mercedes a car won't even start without the cluster being programmed. Didn't know that Cadillac does need programmed too. That's good to keep mileage scammers in check. Thanks

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Thanks y'all for the assistance, I work for an Autozone, here in Colorado, and will be picking up some of that Techron to see if this will correct the issue. If not I'll take it to the guy that replaced the fuel pump back in '09 and see if he has any tricks he can use to make it work right. I did replace the front of the cluster out last year when the old one died (went full out) and it shows the correct mileage and everything but I may also need to take it in and see if there is anything else that needs to be done to it as well...

I'll let you all know what happens!

Sean M.

1997 Cadillac DeVille

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In the 1992-1999 Cadillacs, the IPC module is the master module for the car, and carries the serial numbers, passwords, and option list as well as the mileage. That's the module that talks through the OBD II connector, displays the data from the other modules for scanners, polls them for codes and performs other functions when the car is in the diagnostic mode, etc. Changing that is like a brain transplant to the car, and you need to transplant the memory with it. A licensed (by GM as well as locksmith/speedometer licensed and bonded) AC/Delco speedometer or instrument panel shop can do the job.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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In the 1992-1999 Cadillacs, the IPC module is the master module for the car, and carries the serial numbers, passwords, and option list as well as the mileage. That's the module that talks through the OBD II connector, displays the data from the other modules for scanners, polls them for codes and performs other functions when the car is in the diagnostic mode, etc. Changing that is like a brain transplant to the car, and you need to transplant the memory with it. A licensed (by GM as well as locksmith/speedometer licensed and bonded) AC/Delco speedometer or instrument panel shop can do the job.

On a Mercedes this is called a central gateway. The screwed up part is if you lose over 8 keys total you have to replace the gateway because it can't hold anymore keys. You can deauthorize keys but never delete them. Car comes with 3 keys. You can add 5. After that its about $6000 to fix. Thankfully this design went away after 2007.

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