ECU Voltage

When I checked my voltage at the OBD2 port there was zero drop compared to the battery. I suspect the scan tool may be the reason for the lower reading which is now within a few tenths of a volt. That’s measuring battery voltage with my DVOM and ECU voltage with the scan tool.

There must be something here I’m missing.

Is it possible the voltage is present all the time at pin 2 of F19 and the gauge switches by the ground? Perhaps 11ish volts is the ref voltage before the sending unit rheostat?

 

I double check all my wiring again along with the terminations on the fuse box as well.

 

That's actually how I would expect it to be wired but like I wrote before I don't know Tacomas electrical systems.

 

Then there isn't a connection issue with that power line so you don't need to look under the fuse box, or peel the battery cables insulation, or anything else pertaining to that power line.

Replace the cluster.

 

Roger that, I’ll start looking for a second hand unit

 

Delphi fuel pump assembly taken 12-16-19

Note the fuel level and mileage

 

OEM Toyota assembly as of about 15 minutes ago.Something has definitely changed as far as the indication. 40 miles less to 3/4 of a tank. I’m going to burn through this tank and see how low the gauge goes.

I usually don’t like problems that fix themselves but maybe I’m overthinking the whole thing.

Now to figure out why the engine is knocking and that cool red light is on below the speedo!? LOL

 

Things are still headed in the right direction!! This is dead on so far as the past three times I’ve run the tank dry I was indication 360-370 miles per tank until the engine stalled! The needle looks like it’s slightly above half in the picture but it’s due to the angle, it showed slightly below half from my perspective seated in the truck.

 

This was with the Delphi unit

 

Delphi tank number 2, it was very consistent. Just consistently inaccurate!

 

The Delphi unit is showing inaccurate readings and the OEM shows accurate readings, is that correct?

 

Yes, so far that is correct. What surprises me is all three sending units ohm’d out very closely. Either way, I’ll take it.

 

Well, looks like my problem is still here. I put 20.6 gallons of fuel in the tank and took this picture before I stepped out to refuel. No low fuel level light and the gauge only goes to 1/8 of a tank. Looking for a spare cluster now that I can swap to see if the indication changes. I talked to a few gauge overhaul shops and they indicated they see a fair number of Toyota gauge clusters for speedo and fuel gauge repairs. I wish my cluster was one of the models that had the replaceable fuel gauge module!

 

I just figured out the Delphi/OEM that you were writing about was the sending unit and not the cluster. Lol

 

Since my ECU voltage no longer seems to be a factor here I'm going to continue this investigation and post any new developments in my original thread at
thanks to everyone for the help! I'm not giving up yet!

https://www.tacomaworld.com/threads/fuel-gauge-issue.643605/