Fuel Gauge Reading Zero Fixed

[Al Burdon]

I recently replaced the indicator relay with a self cancelling one.
When patching into the rear brake wire I disconnected the ecu while the ignition was still on.
This caused a ecu fault light on the dash which disappeared after 3 cold - hot cycles.
The fuel level and distance to empty subsequently read Zero and would not reset.
The low tank warning light still illuminated.
I have checked all connectors and found no issues.
Today I removed the fuel senors connector at the tank and reconnected it.
The ecu warning has returned but also the gauge and range to empty has returned.
I don't have an obd2 connector yet but I am assuming the remove and replace had reset the ecu for the fuel sensor input to allow correct calculation from the output volage of the sender.

I have ordered a obd2 connector and cable. What software will allow me to view and reset ecu faults.
I don't need the abilty to load different maps at this time.

 

[Joesmoe]

Well, I would suggest TuneECU, which has ample data and diagnostics, even if you never plan to improve your engine's performance "for free".

The TuneECU version for PC (Windows) is freeware, need to order the Lon-Elec cable from England which is pretty reasonable considering what it enables.

 

[Al Burdon]

Well, I would suggest TuneECU, which has ample data and diagnostics, even if you never plan to improve your engine's performance "for free".

The TuneECU version for PC (Windows) is freeware, need to order the Lon-Elec cable from England which is pretty reasonable considering what it enables.

Thanks mate

I have already ordered the Lon-Elec cable and will check out TuneECU when it arrives.

 

[Al Burdon]

So I got the Lon-Elec cable and connected TuneECU.
Fault code was present for fuel level sender which I cleared.
Tank level and distance to empty still at zero.
So I disconnected and checked the sensor connector at the tank.
Then the level now says full and 300 plus ks to empty(irrespective of actual tank level).
Stays this way and at some time later starts to decrease still not realistic to actual tank level.
I then refill the tank and there is no change to indicated level but it keeps decreasing as you would expect for normal consumption.
When the gauge reaches zero it says there no matter what is in the tank.
Only disconnecting the sensor at the tank and re installing has any noticeable effect. (Which then returns the gauge to full and it all repeats)


I am assuming the open circuit when disconnecting is seen by the ecu as full and then no subsequent change is being transmitted from the tank sensor so the ecu just calculates usage for the display as best it can with no further input from the sender.

I am thinking that I need to replace the fuel sender.
Does any one have the wiring diagram for the 2013 roadster. I have the rocket diagram but it shows the fuel level as an accessory.

 

[Joesmoe]

Check any post by @idk -- he has a link to that data in his signature.

 

[Al Burdon]

Update to the on again of again fuel gauge and distance to empty.

After wiring in some 12V sockets and a usb charging socket I removed the Postive Battery connection and reattached so that the insulated cover fitted properly.
Tank was close to empty so I went for a quick ride to the servo and topped up. I was surprised to see the bar gauge and distance to empty was now working again. It so far has continued to function after the next tank fill.

 

[jake shaw]

I love happy ending's

 

[EasTexRIII]

I love happy ending's

No matter the cost

 

[BigNorm]

I love happy ending's

Me too. But a back rub is nice too.

 

[DodahMan]

Update to the on again of again fuel gauge and distance to empty.

After wiring in some 12V sockets and a usb charging socket I removed the Postive Battery connection and reattached so that the insulated cover fitted properly.
Tank was close to empty so I went for a quick ride to the servo and topped up. I was surprised to see the bar gauge and distance to empty was now working again. It so far has continued to function after the next tank fill.

Would that be the same thing as simply disconnecting the battery cables for a while?