2G Testing, fuel assembly/gas gauge.

[miliman13]

Hey everybody!!!
I ran out of gas... my gauge is a lying whore.

I pulled my pump out months ago to diagnose an issue and since then the car Sat while I built her.

Gauge worked fine before, not anymore!!

First with assembly connected I manually played with lever, no change in gauge .


Then I used a meter to measure resistance on this version of a potentiometer.
These are the values. Based on my limited electrical education I believe the system is operational..

I'm looking at you electrical engineers.. cough ""rally"".

Any advice of further testing..
Thanks.


Following are full tank , half tank and empty tank measurements.

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[dustyboner]

Those numbers look good.

Here is a link to the electrical manual. start on page 437.
http://www.mediafire.com/?6v705mm1dzx

 

[luv2rallye]

Those readings are ok.
If you have an AWD you also need to check the sender on the other side.

Then do this: http://www.dsmtuners.com/threads/fuel-level-gauge-not-working-after-new-pump.332584/#post-151830828

Then this:
http://www.dsmtuners.com/threads/in...w-fuel-light-coming-on.498173/#post-153563185

 

[miliman13]

Those readings are ok.
If you have an AWD you also need to check the sender on the other side.

Then do this: http://www.dsmtuners.com/threads/fuel-level-gauge-not-working-after-new-pump.332584/#post-151830828

Then this:
http://www.dsmtuners.com/threads/fuel-level-gauge-not-working-after-new-pump.332584/#post-151830828

Rally those two links are the same, did you mean to reference something else?

And just for clarity, when you say "ground" do you mean probe the yellow wire and make contact with the chassis?
And I'm assuming the assembly doesn't have to be plugged in for this test.


""2g AWD wiring:
On the stock setup for AWD there are 2 senders in thetank that are connected in series - one on drivers side, one on passenger side."""


Do you mean the white plug and the black plug behind the passenger seat were the pump is. Or is it directly behind the driver's side? I saw a plate but never opened it before.

 

[miliman13]

Those numbers look good.

Here is a link to the electrical manual. start on page 437.
http://www.mediafire.com/?6v705mm1dzx

Thank you that was very helpful, your right i am with in spec.

 

[miliman13]

Please excuse my excessive questions. But I didn't find a clear answer.
The brown plastic container that has the yellow wire leading to it. The manual calls it a thermistor and suggest submerging it in water, doesn't that mean that controls the gas icon on the dash
( that's what I did see but foolishly ignored)

I read it's supposed to be inside the tank..

And how does a thermistor detect low fluid level when it's primary function is to detect temp?

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[luv2rallye]

Please excuse my excessive questions. But I didn't find a clear answer.
The brown plastic container that has the yellow wire leading to it. The manual calls it a thermistor and suggest submerging it in water, doesn't that mean that controls the gas icon on the dash
( that's what I did see but foolishly ignored)

I read it's supposed to be inside the tank..

And how does a thermistor detect low fluid level when it's primary function is to detect temp?

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A thermistor submerged in a liquid reads a different temp than one not submerged so it's useful for turning on the low fuel light.

 

[luv2rallye]

Rally those two links are the same, did you mean to reference something else?

And just for clarity, when you say "ground" do you mean probe the yellow wire and make contact with the chassis?
And I'm assuming the assembly doesn't have to be plugged in for this test.

Do you mean the white plug and the black plug behind the passenger seat were the pump is. Or is it directly behind the driver's side? I saw a plate but never opened it before.

Yes sorry, I corrected the 2nd link in my post 3.

I assume you have AWD is that correct?

By ground I mean the chassis or body (bare metal contact point) to touch/connect the wire to. To test the wiring or dash gauge (by grounding at different wiring points) you don't need the passenger side sender connected but you do the drivers side since it is connected in series (between the passenger side and the dash gauge). If just testing dash gauge (and wiring to it) you don't need senders connected.

For testing I'm talking about on the fuel pump/sender connectors (remove rear seat to see) where they go into the fuel tank to the fuel pump/senders. You don't remove the fuel tank plate for testing as these connectors are on top of it.

Here's another link that may help: http://www.dsmtuners.com/threads/gas-gauge-constantly-lowers.402919/#post-152589939

Attached are the wiring diagrams for the fuel sender and fuel low level thermistor for 2g (note Fuel Gauge Unit E-59 is the passenger side).

 

[miliman13]

I'm grounding every yellow wire that I can find I need a little clarity is it this connector in the picture below

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The image is of what's behind the driver seat I'm assuming there is no fuel pump assembly in there , if so then what is in there?I don't want to open it because the seal will have swollen up by now and that's how I evaporated my gas on the other side.

 

[luv2rallye]

What's in there is one of the two fuel level gauge sensors (other is in passenger side wired in series with this one to ground) and the fuel level switch.

Unplug that connector and ground the all yellow wire. When key is turned to ON (don't start engine) the dash fuel gauge should move to full in about 30 seconds. If it does, then your problem is either in here, or the other side, or the wiring between the two, or the ground connection on the other side.

 

[miliman13]

Using what's available to me I tested what I assumed was correctly and according to the test it's the fuel gauge which it should not be since it was the fuel pump assembly that I had touched and not the actual gauge it appears that I will have to purchase an aftermarket gas gauge..

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[miliman13]

It's there a ground that I can check?

 

[luv2rallye]

http://www.dsmtuners.com/threads/in...w-fuel-light-coming-on.498173/#post-153563185

 

[miliman13]

^thanks again for keeping up with the thread.

You mean the bar underneath the seat, inside the cabin correct?

 

[luv2rallye]

For the ground connection yes. I haven't seen it but that's where it's supposed to be.

 

[miliman13]

I'm having trouble downloading the PDF, so my question is on this harness what is the actual ground?

I want to try to rewire a new ground to do one more test, before I buy an after market gauge ( 0-90ohm range).


I looked up photos of my cabin when it was bare and there's only one ground under the driver's seat and I remember cleaning up and checking it for proper contact.

I rather do a new ground than strip the car again.

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[luv2rallye]

The actual ground for the passenger side sender is the larger all black wire on that 6 pin passenger side connector. This is also the ground for the fuel pump. It goes to the "front floor upper cross member (left side)" grounding point which I think is under the driver's seat as shown in the diagram below (pic #8). You can connect this black wire at the connector to ground if you have a problem with it's normal grounding point (I'd think you would have a fuel pump issue however if that were the case).

However regardless of all that, the solid yellow wire on the driver's side connector goes right to the dash fuel gauge. If you ground it with key ON, the dash gauge should then read full in 30 seconds. If it doesn't, you have a dash gauge (or perhaps a fuse power) problem. The wiring is shown in my post 8 links.

BTW the factory spec on the dash fuel gauge "resistance between fuel gauge and ground" is 122 +/-10 ohms.

 

[miliman13]

I guess it's truly just the gauge...
Rally do you know if the 0 to 90 ohm gauge will work fine on these vehicles, as in will it actually show full or less than full? since full is just under 60 ohms..

 

[luv2rallye]

Don't know. And what measurement are you referring to as 60 ohms?

 

[miliman13]

The empty tank measurement in post 1.
Since it's 60ohms at its max, will it not show "empty" on the gauge.

 

[luv2rallye]

Your post 1 pic shows 3.1 ohms for full which is about right (when full, resistance is the least). Spec is 2 +/-1 ohms for each. Since the senders are in series, when tank is full total resistance is 4 ohms (what the dash gauge will see from senders).

 

[miliman13]

My apologies when I said will it show empty on the gauge, I meant the new aftermarket gauge that reads from 0 to 90 ohms.

I know it's difficult for you to know the answer, but based on your expertise what would you think about using that aftermarket gauge do you believe that it will work properly and accurately display the fuel level. Since it's 0-90ohms.

 

[luv2rallye]

You keep saying the aftermarket gauge is 0-90 ohms or reads from 0-90 ohms. The gauge actually reads a value based on the current that flows through it which is determined by the sender resistance (0 ohms sender resistance causes maximum current flow and maximium gauge deflection). The gauge itself has a fixed resistance.

I think what you mean is the sender that should be used with it is specified at 0-90 ohms. My guess is the gauge would work showing the correct full indication but the empty indication won't be accurate. Will probably still have a gallon or 2 left in the tank when the gauge says it is COMPLETELY empty. That's slightly unfortunate as you'll never know when it's really empty. But it's better than no working gauge at all.

 

[miliman13]

BTW the factory spec on the dash fuel gauge "resistance between fuel gauge and ground" is 122 +/-10 ohms.

I went ahead and tested as well. I'm slightly off spec, gauge needle must be stuck.

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[luv2rallye]

Before you go buying a new dash gauge (or at least in addition) you should also make sure the senders and wiring are working as they are normally connected in series to ground. Unplug the driver's side fuel sender 4 pin connector. Connect your ohmmeter to the harness side all yellow wire and the other ohmmeter probe to a metal ground (no need to turn key on). Make sure the reading is between 4-107 ohms depending on how full your tank is (4=full, 107 is completely empty). If you don't have this you also have a sender/wiring problem independent of any dash gauge issue.