Fuel gauge not working

[Old Navman]

Greetings

I've had a hiccup with the fuel gauge once before - it stopped working for a day or so and then it worked Ok until recently.
I took the pump out and in my haste thinking it's the gauge sender unit changed it. To my disappointment it's not it. After I soldered the new sender unit in (big mistake) I've measured the old one and it seems it was actually working Ok. When I say OK - when measured the ohm values were changing depending on the position of the floater.

So now, I've got the new sender unit soldered in and still no gauge. Again I measured the resistance of the new unit and it also appears to have changing resistance.

What gives?

[kamold]

What's the fault code in the cluster?
That should give you a good idea what the issue is - is it short to ground or plus, is it resistance too high or too low

[MIG]

Measuring the resistance at the cluster and comparing it to the reading you get from the sender, you may have a break in the cable somewhere.

[Old Navman]

Thanks guys,

I'll have to hook up the vcds and post any suspicious fault codes - well, the ones which were not previously there .
When you say 'resistance at the cluster' do you mean the 3 pronged terminal sticking out of the top of the pump? as well as the cable connected to it?

Edit - the below are the photos of the pump cover and top of the pump. The 'insulation work' on the plug was done prior to me acquiring the vehicle.

[Old Navman]

My old laptop's battery unfortunately is u/s so it took me a while to hook up the extension power cord to get the scan going. But in any case here it is:

Thursday,03,August,2023,11:07:17:00009
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 7 x86
VCDS Version: 20.12.0.0
Data version: 20201124 DS322.0
www.Ross-Tech.com

Repair Order: 03082023

Chassis Type: 3C-VW46 (3C0)
Scan: 01 02 03 08 09 15 16 17 19 22 25 36 42 44 46 52 53 56 62 65
69 72 76

VIN: WVWZZZ3CZ6P178475 Mileage: 350510km-217796miles

01-Engine -- Status: Cannot be reached 1100
02-Auto Trans -- Status: Cannot be reached 1100
03-ABS Brakes -- Status: Cannot be reached 1100
04-Steering Angle -- Status: Cannot be reached 1100
08-Auto HVAC -- Status: Cannot be reached 1100
09-Cent. Elect. -- Status: Malfunction 0010
15-Airbags -- Status: Cannot be reached 1100
16-Steering wheel -- Status: OK 0000
17-Instruments -- Status: Malfunction 0010
19-CAN Gateway -- Status: Malfunction 0010
22-AWD -- Status: Cannot be reached 1100
25-Immobilizer -- Status: OK 0000
36-Seat Mem. Drvr -- Status: Malfunction 0010
42-Door Elect, Driver -- Status: Malfunction 0010
44-Steering Assist -- Status: Cannot be reached 1100
46-Central Conv. -- Status: Malfunction 0010
52-Door Elect, Pass. -- Status: Malfunction 0010
53-Parking Brake -- Status: Cannot be reached 1100
56-Radio -- Status: Malfunction 0010
62-Door, Rear Left -- Status: OK 0000
65-Tire Pressure -- Status: OK 0000
69-Trailer -- Status: Cannot be reached 1100
72-Door, Rear Right -- Status: OK 0000
76-Park Assist -- Status: OK 0000

-------------------------------------------------------------------------------
Address 01: Engine Labels: 03H-906-032-BLV.clb
Part No SW: 03H 997 033 K HW: Hardware No
Component: P3.2 FSI-EU4 G00 2368
Revision: --H11--- Serial number: VWZCZ000000000
Coding: 0000175
Shop #: WSC 00028 028 00001
VCID: 356194D35C417F2CE0-8060

1 Fault Found:
012555 - Low Pressure Fuel regulation
P310B - 004 - Fuel Pressure Outside Specification
Freeze Frame:
Fault Status: 01100100
Fault Priority: 0
Fault Frequency: 157
Reset counter: 255
Mileage: 347856 km
Time Indication: 0
Date: 2023.05.19
Time: 07:03:22

Freeze Frame:
RPM: 635 /min
Load: 28.6 %
Speed: 1.0 km/h
Temperature: 72.0°C
Temperature: 29.0°C
Absolute Pres.: 990.0 mbar
Voltage: 13.716 V

Readiness: 0000 0000

-------------------------------------------------------------------------------
Address 02: Auto Trans Labels: 02E-927-770.clb
Part No SW: 02E 300 047 J HW: 02E 927 770 AE
Component: GSG DSG 070 1154
Revision: 04507000 Serial number: 00000602071105
Coding: 0000020
Shop #: WSC 00028 028 00001
VCID: 1F4D567BCEBDD57C1A-804A

No fault code found.

-------------------------------------------------------------------------------
Address 03: ABS Brakes Labels:. 3C0-614-095-C2.clb
Part No SW: 3C0 614 095 Q HW: 3C0 614 095 Q
Component: ESP 440 C2 H015 0003
Revision: H015 Serial number: 0667165431
Coding: 0046535
Shop #: WSC 00028 028 00001
VCID: 306FA5C7A3235A04B3-8064

1 Fault Found:
00778 - Steering Angle Sensor (G85)
008 - Implausible Signal - Intermittent
Freeze Frame:
Fault Status: 00101000
Fault Priority: 3
Fault Frequency: 12
Reset counter: 142
Mileage: 350068 km
Time Indication: 0
Date: 2023.07.18
Time: 22:59:39


-------------------------------------------------------------------------------
Address 08: Auto HVAC (J255) Labels:| 5K0-907-044.clb
Part No SW: 5K0 907 044 EA HW: 5K0 907 044 EA
Component: Climatronic H17 1010
Revision: 00003001
Coding: 0000001002
Shop #: WSC 01324 020 00200
ASAM Dataset: EV_Climatronic A01010
ROD: EV_ClimaAutoBasis_VW46.rod
VCID: 6ED37BBFB1970CF4E1-803A

1 Fault Found:
13701456 - Function Restricted due to Missing Message(s)
U1111 00 [009] - -
[New feature! Extended UDS fault detail is only supported by current gen. interfaces]
Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 6
Fault Frequency: 1
Reset counter: 104
Mileage: 350514 km
Date: 2023.07.31
Time: 11:08:28


-------------------------------------------------------------------------------
Address 09: Cent. Elect. Labels:. 3C0-937-049-23-H.lbl
Part No SW: 3C0 937 049 J HW: 3C0 937 049 J
Component: Bordnetz-SG H37 1301
Revision: 00H37000 Serial number: 00000003835219
Coding: E1848F0700041A00000A00000F00000000085D435C0000
Shop #: WSC 00028 028 00001
VCID: 306FA5C7A3235A04B3-8064

Subsystem 1 - Part No: 3C2 955 119 Labels: 1KX-955-119.CLB
Component: Wischer VW461 012 0503
Coding: 00063445
Shop #: WSC 00028

Subsystem 2 - Part No: 1K0 955 559 T Labels: 1K0-955-559-AF.CLB
Component: RegenLichtSens 011 1110
Coding: 00208933
Shop #: WSC 00028

5 Faults Found:
02394 - Parking Light Left Front (M1)
012 - Electrical Fault in Circuit - Intermittent
Freeze Frame:
Fault Status: 00101100
Fault Priority: 2
Fault Frequency: 5
Reset counter: 143
Mileage: 349923 km
Time Indication: 0
Date: 2023.07.16
Time: 06:25:00

Freeze Frame:
ON
Voltage: 11.80 V
ON
ON
OFF
OFF
OFF

01496 - Bulb for Fog-Lamps; Left (L22)
010 - Open or Short to Plus - Intermittent
Freeze Frame:
Fault Status: 00101010
Fault Priority: 4
Fault Frequency: 20
Reset counter: 130
Mileage: 348055 km
Time Indication: 0
Date: 2023.05.22
Time: 18:01:00

Freeze Frame:
ON
Voltage: 13.85 V
ON
ON
OFF
OFF
OFF

01500 - Bulb for Fog-Lamps; Right (L23)
010 - Open or Short to Plus - Intermittent
Freeze Frame:
Fault Status: 00101010
Fault Priority: 4
Fault Frequency: 12
Reset counter: 130
Mileage: 348055 km
Time Indication: 0
Date: 2023.05.22
Time: 18:00:00

Freeze Frame:
ON
Voltage: 13.80 V
ON
ON
OFF
OFF
OFF

01517 - Control Module for Trailer/Towing Sensor (J345)
004 - No Signal/Communication - Intermittent
Freeze Frame:
Fault Status: 00100100
Fault Priority: 2
Fault Frequency: 254
Reset counter: 144
Mileage: 347974 km
Time Indication: 0
Date: 2023.05.21
Time: 13:28:00

Freeze Frame:
OFF
Voltage: 13.20 V
OFF
ON
OFF
OFF
OFF

01320 - Control Module for Climatronic (J255)
004 - No Signal/Communication - Intermittent
Freeze Frame:
Fault Status: 00100100
Fault Priority: 2
Fault Frequency: 254
Reset counter: 144
Mileage: 347974 km
Time Indication: 0
Date: 2023.05.21
Time: 13:28:00

Freeze Frame:
OFF
Voltage: 13.25 V
OFF
ON
OFF
OFF
OFF

-------------------------------------------------------------------------------

[Old Navman]

-------------------------------------------------------------------------------

Address 15: Airbags Labels: 3C0-909-605.lbl
Part No SW: 3C0 909 605 K HW: 3C0 909 605 K
Component: 17 AIRBAG VW8R 029 2521
Revision: 10029000 Serial number: 003A3P1ZPVBF
Coding: 0012599
Shop #: WSC 00028 028 00001
VCID: 2E53BBBFB9174CF4A1-807A

Subsystem 1 - Serial number: 6332MSME0F5F0E3BY

Subsystem 2 - Serial number: 6342MSME0F49367AQ

Subsystem 3 - Serial number: 6351HTS64IKAP662E

Subsystem 4 - Serial number: 6361HTS64IKQDAR21

Subsystem 5 - Serial number: 00000000000000000

Subsystem 6 - Serial number: 00000000000000000

No fault code found.

-------------------------------------------------------------------------------
Address 16: Steering wheel Labels: 3C0-953-549-SW20.lbl
Part No SW: 3C0 953 549 E HW: 3C0 953 549 E
Component: J0527 0015
Revision: 00005000 Serial number: 3C5953507P
Coding: 0001111
Shop #: WSC 00028 028 00001
VCID: 2E53BBBFB9174CF4A1-807A

Subsystem 1 - Part No: XXXXXXXXXXX
Component: E0221 007 0050

No fault code found.

-------------------------------------------------------------------------------
Address 17: Instruments Labels: 3C0-920-xxx-17.lbl
Part No SW: 3C0 920 870 P HW: 3C0 920 870 P
Component: KOMBIINSTRUMENT VD1 4240
Revision: X0033000 Serial number: 00000000000000
Coding: 0007705
Shop #: WSC 30081 959 88100
VCID: 306FA5C7A3235A04B3-8064

2 Faults Found:
00438 - Fuel Supply Sensor 2 (G169)
003 - Mechanical Failure
Freeze Frame:
Fault Status: 01100011
Fault Priority: 2
Fault Frequency: 1
Reset counter: 59
Mileage: 349196 km
Time Indication: 0
Date: 2023.06.24
Time: 20:27:36

00438 - Fuel Supply Sensor 2 (G169)
010 - Open or Short to Plus - Intermittent
Freeze Frame:
Fault Status: 00101010
Fault Priority: 2
Fault Frequency: 2
Reset counter: 138
Mileage: 350289 km
Time Indication: 0
Date: 2023.07.26
Time: 17:08:55


-------------------------------------------------------------------------------
Address 19: CAN Gateway Labels:. 3C0-907-530-V3.clb
Part No SW: 3C0 907 530 Q HW: 3C0 907 951
Component: J533 Gateway H13 0172
Revision: H13 Serial number: 3640P151190AC5
Coding: FD82FF4F00020200F103
Shop #: WSC 12345 123 12345
VCID: 2F6DA6BBBE1D45FCAA-807A

2 Faults Found:
01320 - Control Module for Climatronic (J255)
004 - No Signal/Communication - Intermittent
Freeze Frame:
Fault Status: 00100100
Fault Priority: 2
Fault Frequency: 254
Reset counter: 144
Mileage: 347974 km
Time Indication: 0

01517 - Control Module for Trailer/Towing Sensor (J345)
004 - No Signal/Communication - Intermittent
Freeze Frame:
Fault Status: 00100100
Fault Priority: 2
Fault Frequency: 254
Reset counter: 144
Mileage: 347974 km
Time Indication: 0


-------------------------------------------------------------------------------
Address 22: AWD Labels: 1K0-907-554.lbl
Part No: 1K0 907 554 C
Component: HALDEX 4Motion 0108
Coding: 0000001
Shop #: WSC 00000 000 00000
VCID: 2D51BCB3B41137EC98-8078

No fault code found.

-------------------------------------------------------------------------------
Address 25: Immobilizer Labels: 3C0-959-433-25.clb
Part No SW: 3C0 959 433 P HW: 3C0 959 433 P
Component: IMMO 043 0364
Revision: 00043000 Serial number: VWZCZ000000000
Shop #: WSC 131071 1023 2097151
VCID: 377D9EDB464D8D3CF2-8062

Subsystem 1 - Part No: 3C0 905 861 D
Component: ELV 024 0370
3C0905861D ELV 024 0370

No fault code found.

-------------------------------------------------------------------------------
Address 36: Seat Mem. Drvr Labels: 3C0-959-760.lbl
Part No SW: 3C0 959 760 B HW: 3C0 959 760 B
Component: Sitzverstellung 0701
Revision: 00003000 Serial number: 00000000000000
Shop #: WSC 00000 000 00000
VCID: 2C57B1B78F0B3EE48F-8078

No fault code found.

-------------------------------------------------------------------------------
Address 42: Door Elect, Driver Labels: 1K0-959-701-MAX2.lbl
Part No: 1K0 959 701 L
Component: Tuer-SG 024 2462
Coding: 0000951
Shop #: WSC 00028 028 00001
VCID: 377D9EDB464D8D3CF2-8062

1 Fault Found:
00131 - Outside Door Handle Illumination/mirror Light Driver Side
012 - Electrical Fault in Circuit - Intermittent

-------------------------------------------------------------------------------
Address 44: Steering Assist Labels: 1Kx-909-144-G2V2.clb
Part No: 1K2 909 144 K
Component: EPS_ZFLS Kl.5 D06 1701
Shop #: WSC 00000 000 00000
VCID: 3467A9D7573B6624D7-8060

No fault code found.

-------------------------------------------------------------------------------
Address 46: Central Conv. Labels:. 3C0-959-433-46.clb
Part No SW: 3C0 959 433 P HW: 3C0 959 433 P
Component: KSG PQ46 RDK 043 0213
Revision: 00043000 Serial number: VWZCZ000000000
Coding: 01910A0801860E76380694157008DFCE101800
Shop #: WSC 00028 028 00001
VCID: 377D9EDB464D8D3CF2-8062

Subsystem 1 - Part No: 1K0 951 605 C
Component: LIN BACKUP HORN H03 1301

Subsystem 2 - Part No: 3C0 951 171 A
Component: Neigungssensor 002 0508

Subsystem 3 - Part No: 3C0 951 171 A
Component: Innenraumueberw.002 0508

2 Faults Found:
01517 - Control Module for Trailer/Towing Sensor (J345)
004 - No Signal/Communication - Intermittent
Freeze Frame:
Fault Status: 00100100
Fault Priority: 4
Fault Frequency: 254
Reset counter: 144
Mileage: 347974 km
Time Indication: 0
Date: 2023.05.21
Time: 13:28:24

01320 - Control Module for Climatronic (J255)
004 - No Signal/Communication - Intermittent
Freeze Frame:
Fault Status: 00100100
Fault Priority: 4
Fault Frequency: 254
Reset counter: 144
Mileage: 347974 km
Time Indication: 0
Date: 2023.05.21
Time: 13:28:24

-------------------------------------------------------------------------------

[Old Navman]

-------------------------------------------------------------------------------

Address 52: Door Elect, Pass. Labels: 1K0-959-702-MAX2.lbl
Part No: 1K0 959 702 L
Component: Tuer-SG 024 2462
Coding: 0000950
Shop #: WSC 00028 028 00001
VCID: 387F9DE74B538244FB-806C

1 Fault Found:
00132 - Outside Door Handle Illumination/mirror Light Passenger Side
012 - Electrical Fault in Circuit - Intermittent

-------------------------------------------------------------------------------
Address 53: Parking Brake Labels: 3C0-907-801-53.clb
Part No SW: 3C0 907 801 B HW: 3C0 907 801 B
Component: EPB VC8HC001 013 0001
Revision: 013
Coding: 0000012
Shop #: WSC 30087 959 68769
VCID: 21495083F8C9E38C2C-8074

No fault code found.

-------------------------------------------------------------------------------
Address 56: Radio (J503) Labels:. 5M0-035-1xx-56.clb
Part No SW: 3AD 035 190 A HW: 3AD 035 190 A
Component: RCD510USBRVC 003 0003
Revision: -----001 Serial number: VWZ4Z3P8053234
Coding: 01000425040010
Shop #: WSC 00079 790 12345
VCID: 2B55B2AB4A0539DC86-807E

1 Fault Found:
01317 - Control Module in Instrument Cluster (J285)
004 - No Signal/Communication
Freeze Frame:
Fault Status: 01100100
Fault Priority: 6
Fault Frequency: 1
Reset counter: 14
Mileage: 347908 km
Time Indication: 0
Date: 2023.05.20
Time: 14:47:44


-------------------------------------------------------------------------------
Address 62: Door, Rear Left Labels: 1K0-959-703-GEN2.lbl
Part No: 1K0 959 703 F
Component: Tuer-SG 021 2432
Coding: 0000144
Shop #: WSC 00028 028 00001
VCID: 3365AACB5235611CCE-8066

No fault code found.

-------------------------------------------------------------------------------
Address 65: Tire Pressure Labels: 3C0-959-433-65.lbl
Part No SW: 3C0 959 433 P HW: 3C0 959 433 P
Component: RDK 0391
Revision: 00043000 Serial number: VWZCZ000000000
Coding: 0161210
Shop #: WSC 12345 123 12345
VCID: 377D9EDB464D8D3CF2-8062

No fault code found.

-------------------------------------------------------------------------------
Address 69: Trailer Labels: 1K0-907-383-V1.clb
Part No SW: 1K0 907 383 HW: 1K0 907 383
Component: ANHAENGERELEKTR 003 0020
Coding: 0000001
Shop #: WSC 00000 000 00000
VCID: 6ADB77AF457FE0D4BD-803E

No fault code found.

-------------------------------------------------------------------------------
Address 72: Door, Rear Right Labels: 1K0-959-704-GEN2.lbl
Part No: 1K0 959 704 F
Component: Tuer-SG 021 2432
Coding: 0000144
Shop #: WSC 00028 028 00001
VCID: 3467A9D7573B6624D7-8060

No fault code found.

-------------------------------------------------------------------------------
Address 76: Park Assist Labels: 3C0-919-283.lbl
Part No SW: 3C0 919 283 B HW: 3C0 919 283 B
Component: Parkhilfe 8-Kan 004 0011
Revision: 00004000 Serial number: 82930602501458
Coding: 0011014
Shop #: WSC 30081 959 88100
VCID: 285F4DA79BF312C46B-807C

No fault code found.

End-------------------------(Elapsed Time: 02:49)--------------------------

[MIG]

2 Faults Found:
00438 - Fuel Supply Sensor 2 (G169)
003 - Mechanical Failure
Freeze Frame:
Fault Status: 01100011
Fault Priority: 2
Fault Frequency: 1
Reset counter: 59
Mileage: 349196 km
Time Indication: 0
Date: 2023.06.24
Time: 20:27:36

00438 - Fuel Supply Sensor 2 (G169)
010 - Open or Short to Plus - Intermittent
Freeze Frame:
Fault Status: 00101010
Fault Priority: 2
Fault Frequency: 2
Reset counter: 138
Mileage: 350289 km
Time Indication: 0
Date: 2023.07.26
Time: 17:08:55

I would guess there is an open circuit somewhere. Check out this wiring diagram; I would be checking the plug at the cluster a 36-pin and checking its connectivity to the 3-pin connector at the tank.

[Old Navman]

2 Faults Found:
00438 - Fuel Supply Sensor 2 (G169)
003 - Mechanical Failure
Freeze Frame:
Fault Status: 01100011
Fault Priority: 2
Fault Frequency: 1
Reset counter: 59
Mileage: 349196 km
Time Indication: 0
Date: 2023.06.24
Time: 20:27:36

00438 - Fuel Supply Sensor 2 (G169)
010 - Open or Short to Plus - Intermittent
Freeze Frame:
Fault Status: 00101010
Fault Priority: 2
Fault Frequency: 2
Reset counter: 138
Mileage: 350289 km
Time Indication: 0
Date: 2023.07.26
Time: 17:08:55

I would guess there is an open circuit somewhere. Check out this wiring diagram; I would be checking the plug at the cluster a 36-pin and checking its connectivity to the 3-pin connector at the tank.

[ATTACH=CONFIG]55381[/ATTACH]

Thanks for the information MIG

I'm hoping it's not the 'new' sender unit I installed (seems unnecessarily) about a week ago. I did check it's resistance prior to fitting and it appeared to be working Ok. That 3 pronged plug on the top of the pump seem OK too - from memory there was a continuity between. at least, 2 terminals? However, if all 3 have to have continuity then something is NQR. I'll have to re-check this again.

As to the T36 connector - where exactly does it plug in? Must be somewhere at the back of the cluster display? So, this could be 'the cluster' you guys were talking about. If so, I'd have to research how to take the cluster out to check that connector.

[MIG]

Maybe go back to the basics before pulling the cluster.

Check the three pins first.
One pin should be to ground (pin1 brown\blue); one should be a reference voltage and the other the sense wire for the sender.


Maybe look under that tape mess

[kamold]

There is a useful post on the Ross Tech forum which explains the differences between short to plus, short to ground faults etc:

Testing - Open Circuits, Short to Ground or Positive, etc.... | Ross-Tech Forums

[Old Navman]

There is a useful post on the Ross Tech forum which explains the differences between short to plus, short to ground faults etc:

Testing - Open Circuits, Short to Ground or Positive, etc.... | Ross-Tech Forums

Thanks - it'll be tonight's reading

[Old Navman]

There is a useful post on the Ross Tech forum which explains the differences between short to plus, short to ground faults etc:

Testing - Open Circuits, Short to Ground or Positive, etc.... | Ross-Tech Forums

Today I've tried troubleshooting this

1 - checking the plug (as below - ignition on) resulted in 0.9V between the connector 2-3 blue purple/white wire and 0V on brown/blue stripe earth? wire.
2 - Testing for Short to Ground (as per Ross Tech) produced battery voltage 0.9V
3 - Testing for Short to Positive (as per Ross Tech) showed 12V.

There does not seem to be a specific fuse to cover fuel gauge that I could find? but is there any way to power up and check the gauge itself?

[Old Navman]

An update (sort of) - I've had one of the TTY guys have a look at this for me. Despite swapping Fuel Pump Controller (from R36 I think it was), both fuel sender units he was unable to pinpoint where the fault is. In any case the fuel sender units (in the car) were testing a moving resistance and the fuel gauge itself needle could be moved using the VCDS so unlikely indicating a mechanical fault to the gauge itself.

[MMR36]

Hi,

Maybe a longshot...

I had a fuel supply issue a couple of years back with a low fuel pressure sensor fault. Long story short, once the sensor was replaced and couple of other bits, all the hardware was good, save for the gauge measuring. Turned out the coding for the gauge was corrupted. The tank characteristic curve for the left tank (from memory) was missing and the gauge 'code' could only see one tank. Therefore, fuel load was incorrectly calculated (not helpfully, above what was in the tanks) so just over half full on the gauge was empty tanks.

Perhaps check the tank characteristic curves in the coding for your dash. (I note mine is a later dash than yours)

Cheers

An update (sort of) - I've had one of the TTY guys have a look at this for me. Despite swapping Fuel Pump Controller (from R36 I think it was), both fuel sender units he was unable to pinpoint where the fault is. In any case the fuel sender units (in the car) were testing a moving resistance and the fuel gauge itself needle could be moved using the VCDS so unlikely indicating a mechanical fault to the gauge itself.