Fuel gauge issues

[Brandini]

I recently removed all my gauges to replace the glass and chrome bezels. After a good cleaning and placing the gauges back in I noticed my fuel gauge is no longer working. (It was working fine before). Any ideas on what the issue could be?

Also, on a separate note, the back lit lights for the guage that includes the fuel, oil, etc won’t turn on when I active the headlights. I’ve tried turning the knob on the gauge right and left but nothing happens. It’s never worked since I’ve had the car and would like to fix it. Would appreciate any help or advice. 

[BobH]

Hello Brandon, did you break open the 12 way connector when you removed the cluster?, it may be worth just checking the wire connections inside to make sure all the solder joints look good, and the connector has been put back together firmly

It may be that your fuel gauge sender has decided to fail, seems like a coincidence, but it can happen.  The quickest way to rule this out is to take the lid off the plug on top of the sender, to expose the wires, and then short between brown and blue/black, with the ignition on the gauge should indicate full.  Then short between brown and blue/green, the low fuel lamp should light.  If the gauge and lamp both work, then it looks like you have a bad sender.  If it still doesn't work check that the sender plug has a good earth connection, the brown wire, i think it connects to earth somewhere near the left hinge in the boot/trunk, or for testing just run a temporary earth to the sender plug

if all this fails you may just have a failed gauge, do a few of the above tests and let us know the results

I assume you've checked the cluster back light bulb and bulb holder?  The cluster back light is fed through the rheostat, the dimmer switch, you said this made no difference when turned, so it could have failed, however this also feeds the speedo and tacho back lights, are they working?  If not and the dimmer switch has failed they can be replaced, possibly repaired, or simply shorted out.  If the other back lights are still working then a bit more investigation is needed, and time to get the ohm/volt meter out

See what you find

[Brandini]

Hello Brandon, did you break open the 12 way connector when you removed the cluster?, it may be worth just checking the wire connections inside to make sure all the solder joints look good, and the connector has been put back together firmly

It may be that your fuel gauge sender has decided to fail, seems like a coincidence, but it can happen.  The quickest way to rule this out is to take the lid off the plug on top of the sender, to expose the wires, and then short between brown and blue/black, with the ignition on the gauge should indicate full.  Then short between brown and blue/green, the low fuel lamp should light.  If the gauge and lamp both work, then it looks like you have a bad sender.  If it still doesn't work check that the sender plug has a good earth connection, the brown wire, i think it connects to earth somewhere near the left hinge in the boot/trunk, or for testing just run a temporary earth to the sender plug

if all this fails you may just have a failed gauge, do a few of the above tests and let us know the results

I assume you've checked the cluster back light bulb and bulb holder?  The cluster back light is fed through the rheostat, the dimmer switch, you said this made no difference when turned, so it could have failed, however this also feeds the speedo and tacho back lights, are they working?  If not and the dimmer switch has failed they can be replaced, possibly repaired, or simply shorted out.  If the other back lights are still working then a bit more investigation is needed, and time to get the ohm/volt meter out

See what you find

Thank you for the detailed response Bob. I did open the 12 way connector to replace all the bulbs with LED's. I will check and make sure the solders didn't get damaged in the process. I did have a difficult time putting it back together as I think the LED lights are just a tad bit longer. I will let you know what I discover.

With regards to the center gauge back lit lights I went ahead and ordered a new rheostat. I tried bridging the (9 & 11) pins on the connector as indicated in a previous post I found to bypass, but the fuse kept blowing for some reason. My Speedo & Tach lights are working but they are connected to a separate wire that someone ran at some point to the main terminal.

Thanks again for the help!

[BobH]

Hello Brandon, bridging out the rheostat shouldn't blow any fuses, so something's not quite right with the wiring, plus you say there is a rogue wire been added or rerouted. It's best to get it back to original, nothing worse than undocumented DIY mods, if you want to, make some notes and take some pictures and i'm sure we can sort it

[lpeterssen]

Dear Brandon:

It would be of much help to decode this enigma to indicate which fuse in particular is blowing out.

Best regards

Eng.Leonardo Peterssen
Www.wiredoktor.com

[Brandini]

Dear Brandon:

It would be of much help to decode this enigma to indicate which fuse in particular is blowing out.

Best regards

Eng.Leonardo Peterssen
Www.wiredoktor.com

The #7 fuse is the one that keeps blowing after I bridged the pins (9 & 11) on the center gauge 12 pin connector.

Is there suppossed to be separate grounding wire for the center gauge like the speedo and tach or is the ground wire run through the 12 pin connector?   

[BobH]

Hello Brandon, the pin numbering can be slightly confusing, just to make sure, it's the grey/violet and grey/blue wires, on the male side of the connector

You may have seen this post, if not it shows the pins

https://www.sl113.org/forums/index.php?topic=28884.msg281817#msg281817

The ground for the cluster lamps is via the loom from the 12 way connector.  If you'd lost the ground, other lamps wouldn't be working.  The ground for the gauge comes from the fuel gauge sender

[Brandini]

Hello Brandon, the pin numbering can be slightly confusing, just to make sure, it's the grey/violet and grey/blue wires, on the male side of the connector

You may have seen this post, if not it shows the pins

https://www.sl113.org/forums/index.php?topic=28884.msg281817#msg281817

The ground for the cluster lamps is via the loom from the 12 way connector.  If you'd lost the ground, other lamps wouldn't be working.  The ground for the gauge comes from the fuel gauge sender

Thanks Bob - yes, that is the post I have been referring to. I believe I am bridging the correct pins - see attached photo.

Thanks again for all the help I really appreciate it. There's nothing I hate more than electrical issues.   

[BobH]

There seems to be something amiss here.  If you have access to an ohm meter, you should be able to read the rheostat if you measure across these two pins, a good rheostat should measure 0 ohms when turned one way, fully off, no resistance, and less than 20 ohms, when turned the other way, fully on.  Hence shorting these pins just replicates the rheostat being fully off

You could bench test the cluster and lamp, or LED by applying ground -12V to the brown wire, and +12V to the grey/blue wire, although i'd be a bit wary until we know everything has been connected as it should, and nothing has been altered

You might also want to check on ohms range, between brown/ground and the grey violet wire, and between brown and grey blue wire, if you remove the cluster light LED, you should read 0 ohms, i wonder if it's possible your rheostat is breaking down to earth somehow.  If it's breaking down to earth that would explain the ruptured fuse

One more thought, have you checked that the LED you fitted is good?  if it's short circuit and the rheostat is open circuit, then no light and no blown fuse.  If you then short out the rheostat you have a complete short from +12 to earth

[Pawel66]

Fuse number 7 is for car lights and also for instruments illumination. You have a short there. My bet is the clamp holding the speedo or the clamp holding the tacho in place - they often interfere with bulbs wiring, especially if wrongly fitted, which happens frequently.

Check your speedo and tacho mounting clamps if they do not touch positive connectors of the bulbs. You may insulate the clamps with some insulting tape, but correct fitting needs to take place.

Non-working fuel gauge may be a different topic. My experience is that sometimes you may fit it in the instrument cluster frame slightly incorrectly or if you tighten its holding screws too much - it stops working as there is a tension preventing needle from movement. If you have multimeter, you may check if it is getting power from fuse and ground from sender. If you wiggle it a bit and loosen its holding screws - you may see it going back to life. Especially if it is an aftermarket gauge.

That would be my two cents.

[yves]

May be i am wrong for your Problem Brandini, but when i replaced my bulbs with LED in the central cluster,  i had an issue with the red ignition light despite connecting a resistor on the led wiring as i saw here on the forum .
This led has been replced by a "classic" bulb and i had no more issue!
BTW i had also refurbished the Rheostat but at the end it was non realy effective, so i shorted it without any issue...!

[Pawel66]

You cannot replace the charging light with LED. This bulb works a bit differently....

[yves]

It's exactly what i learned....!

[lpeterssen]

Dear Brandon

As everybody here said you for sure have a short on the lines going to rheostat or you inverted the position of one of them with ground (brown wire next to them) or your bridge between gray/violet (input from fuse 7) and gray/blue output for background lighting on all instrument cluster accesories is touching ground
somewhere.

Note how close the ground post is to the wires that you you bridged…..   I think you overheated the cables during soldering of the bridge and insulation is compromissed.

Best regards
L.Peterssen
Www.wiredoktor.com

[Brandini]

Fuse number 7 is for car lights and also for instruments illumination. You have a short there. My bet is the clamp holding the speedo or the clamp holding the tacho in place - they often interfere with bulbs wiring, especially if wrongly fitted, which happens frequently.

Check your speedo and tacho mounting clamps if they do not touch positive connectors of the bulbs. You may insulate the clamps with some insulting tape, but correct fitting needs to take place.

Non-working fuel gauge may be a different topic. My experience is that sometimes you may fit it in the instrument cluster frame slightly incorrectly or if you tighten its holding screws too much - it stops working as there is a tension preventing needle from movement. If you have multimeter, you may check if it is getting power from fuse and ground from sender. If you wiggle it a bit and loosen its holding screws - you may see it going back to life. Especially if it is an aftermarket gauge.

That would be my two cents.

Thank you Pawel for the info on the fuel gauge - I will check this out once I have a free moment and report back.

[Brandini]

May be i am wrong for your Problem Brandini, but when i replaced my bulbs with LED in the central cluster,  i had an issue with the red ignition light despite connecting a resistor on the led wiring as i saw here on the forum .
This led has been replced by a "classic" bulb and i had no more issue!
BTW i had also refurbished the Rheostat but at the end it was non realy effective, so i shorted it without any issue...!

Thank you for the example. I did replace my red ignition light with a LED bulb but it does work when I turn the key. Are you saying I should replace back with a classic bulb?