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Discussion Starter · #1 · (Edited)
On my way to work this morning I had 7/8 bars of fuel. On my way home, I started out that way, then the gauge went into the following state (image below). It stayed that way for about five minutes, then went back to 7/8 bars. It went back and forth like that until I got home where appears to have remained "red."

I didn't have a chance to stop at a gas station but I fueled up on Tuesday so I am pretty sure I've got plenty of gas. Plus the switch back to 7/8 bars. I haven't been able to find any indications of this behavior online.

Although I feel like I should only have about 5/8 bars at this point in the week. So that's odd too.

All that being said, I have a 2011 S60 T6 with the TFT retrofit (two tapped wires from OBDII). I'm wondering if some of my wiring has become lose, or what. I find it odd that I'm getting the red light as I would think I'd get no light at all if the wiring was faulty but who knows.

Any input appreciated as this is a bit unnerving. Red, to me, normally indicates something very bad is happening.

 

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On my way to work this morning I had 7/8 bars of fuel. On my way home, I started out that way, then the gauge went into the following state (image below). It stayed that way for about five minutes, then went back to 7/8 bars. It went back and forth like that until I got home where appears to have remained "red."

I didn't have a chance to stop at a gas station but I fueled up on Tuesday so I am pretty sure I've got plenty of gas. Plus the switch back to 7/8 bars. I haven't been able to find any indications of this behavior online.

All that being said, I have a 2011 S60 T6 with the TFT retrofit (two tapped wires from OBDII). I'm wondering if some of my wiring has become lose, or what. I find it odd that I'm getting the red light as I would think I'd get no light at all if the wiring was faulty but who knows.

Any input appreciate as this is a bit unnerving. Red, to me, normally indicates something very bad is happening.
Red bar is normal for TFT equipped cars when you're below 0 miles remaining. It's the car's way of telling you its driving on its fuel reserves.
What isn't normal is for it to drop from 7/8 straight to red. Start with the obvious checks first, grab a code reader that can pull OBD values and see the fuel remaining value when this happens again.
 

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The red means it's running on fumes. I only had that happen to me once and it was legit, not like in your case.
Did you check the integrity of the wires tapped behind the OBD2?
Of course, if that does not work you'd whi to check the other end which is the plug that goes into the TFT. That would be a pain but you'd have to do it. It's more susceptible depending on the kind of small plug you used back there.
I never had an issue with mine.

Sent from my ASUS_Z017DA using Tapatalk
 

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Discussion Starter · #4 ·
Red bar is normal for TFT equipped cars when you're below 0 miles remaining. It's the car's way of telling you its driving on its fuel reserves.
What isn't normal is for it to drop from 7/8 straight to red. Start with the obvious checks first, grab a code reader that can pull OBD values and see the fuel remaining value when this happens again.
That's a good idea. I actually have a Kiwi USB module that I stopped using after I got the TFT. Lemme check.

Ok, I created a dash real quick in OBD Fusion because (of course) the TFT fuel gauge is reading fine now. So I guess the idea is that next time I see red I can confirm with the ODBII reading. If they agree then it's not the TFT. If, however, they disagree (ie., the TFT is red and the ODBII reading says I have fuel) then my wiring is faulty.

 

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That's a good idea. I actually have a Kiwi USB module that I stopped using after I got the TFT. Lemme check.

Ok, I created a dash real quick in OBD Fusion because (of course) the TFT fuel gauge is reading fine now. So I guess the idea is that next time I see red I can confirm with the ODBII reading. If they agree then it's not the TFT. If, however, they disagree (ie., the TFT is red and the ODBII reading says I have fuel) then my wiring is faulty.
You got it. :thumbup:

Add a large graph too just in case it happens too quickly or you're not in a position to stop the car.

good luck!
 

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I had a similar experience a few years ago but with the original gauge cluster
https://forums.swedespeed.com/showt...-or-Horrible-Fuel-Economy&highlight=gas+gauge

I assumed it was the fuel level sending unit and was planning to have it replaced until I researched the cost. Ever since then I make sure to reset my trip computer as a second opinion. If it is the fuel level sensor an OBDII reader won't be of any help. Fortunately for me it has never happened (that I've noticed) again.
 

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Perhaps I should add ... I installed the TFT about one year ago, maybe more.
.. and the plot thickens.

No need to load up the parts cannon when you've got perfectly good diagnostic options.

I'm thinking OBD will rule out the fuel sensor. Hopefully the graph will also have high enough resolution to show you the possibility of an erratic signal.

If the issue occurs again and there's nothing on OBD, next will be inspecting your OBD port connector itself & the wire taps for the DIM; its probably a good idea to double back on the DIM swap thread to see what each wire tap does.
Individually removing taps + removing both taps will be the next definitive tests to reproduce the issue on the DIM.

Last thing I have in mind is to swap back to your old gauge cluster narrow the issue down to modifications done as part of the DIM swap.

Beyond these I'd just live with the issue; chalk it up to the DIM swap and move on.

Happy hunting!
 

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Discussion Starter · #9 · (Edited)
.. and the plot thickens.
I'm thinking OBD will rule out the fuel sensor. Hopefully the graph will also have high enough resolution to show you the possibility of an erratic signal.
Oddly (or perhaps annoyingly) it didn't go red once on the way to work today. My ODBII graph did show some randomness. But I'm chalking that up to the actual sensor (float?) moving around. I lost the graph when I shut down ODB Fusion (grrr) so I'll have to make a new one to post tonight.
 

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..

If the issue occurs again and there's nothing on OBD, next will be inspecting your OBD port connector itself & the wire taps for the DIM; its probably a good idea to double back on the DIM swap thread to see what each wire tap does.
Individually removing taps + removing both taps will be the next definitive tests to reproduce the issue on the DIM.
The two taps add a second CAN bus to the DIM. This adds fuel economy and gear selector information to the TFT DIM. The fuel gauge will work without this bus. Also, the bus requires both connections to work. Removing one connector or the other will produce the same results, no fuel economy or gear selector LEDs.

Pretty sure this issue is not with the DIM swap. It could be the DIM itself though so if this issue is repeatable swapping to your original would eliminate the DIM as the culprit.
 

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Discussion Starter · #11 ·
The two taps add a second CAN bus to the DIM. This adds fuel economy and gear selector information to the TFT DIM. The fuel gauge will work without this bus. Also, the bus requires both connections to work. Removing one connector or the other will produce the same results, no fuel economy or gear selector LEDs.

Pretty sure this issue is not with the DIM swap. It could be the DIM itself though so if this issue is repeatable swapping to your original would eliminate the DIM as the culprit.
Thanks, that's very good info. I did recall that the CAN bus taps give us gear selector but I was a bit fuzzy on the 2nd variable (eg., fuel economy or fuel level).

I think I can also verify with the OBD2 reading from the Kiwi module (bluetooth) and OBD Fusion (software that reads from it that I can keep running in the background on my phone while I drive). If the DIM fuel indicator goes red again then the OBD2 values should also show something odd.

Man I hope it's not the DIM as I was really lucky to get a compatible one. I think it was from a 2014 or 2015 s60. I forget. Which was the recommended year to swap into a 2011?
 
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