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Discussion Starter · #1 ·
I found a few posts in the past dealing with fuel gauges that don't read correctly. Mine just suddenly started reading 1/2 to 3/4 after a complete fill.

Is there a DYI post on checking/replacing the fuel level senders?

I have read that some folks report that the fuel pump runs when opening doors, which is bad news if you are working on the pumps or fuel lines. I went to the trunk to remove the fuel pump fuse, but I cannot correlate the fuse numbers with the actual positions of the fuses. I have quite a few fuses missing and the socket numbers/positions don't seem to correlate with the actual fuse placement. Is there fuse # labels on the actual fuse sockets?

There is also mention of the "secret menu" that allows you to see the different levels of the senders in both tanks. Where actually is this menu displayed? On the steering column or on the LCD display in the center console?

Thanks in adavnce for any help.
 

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There IS a Console Test for fuel levels. # 4 or # 6, can't remember exactly. They show up in the console message area until the car generates a "BEEP," in which case the messages turn off, and you have to go back and activate them again. Do a couple more searches ... they is MORE than enough info here on fuel levels, guages, sensor error codes, secret console messages. Sometime leaving the key in the ignition will keep the computers from updating your fuel guage. It will move over time to the correct reading, however. Also, in the Owner's Manual, it even states that the fuel gauge will not be "updated," if you put less than 1/4 tank of gas in.
 

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Discussion Starter · #5 ·
OK. This is what is confusing me. The FAQ talks about a "secret menu" accessed through the LCD display in your center console:

http://www.m5board.com/vbulletin/e3...ou-never-knew-you-could-have-secret-menu.html

In the posts on fuel pumps and fuel gauges, people talk about another "secret menu" displayed via the LED readouts above the steering column (I assume) that is manipulated by the two buttons in the instrument cluster. Which "secret menu" are you guys refering to? Also, there is nothing in the FAQ above refering to "test #6".

Also, I have searched and searched but cannot find a photo of the actual fuse location. I know where the fuse is supposed to be (#54), but there are no fuse numbers identified on the actual fuse block. Since many of the fuses are missing, the actual fuses don't seem to match up to the label on the vanity cover. Am I missing something obvious?

Also, regarding the gauge, the car has been turned off and restarted a number of times and the gauge still reads 3/4, even though the tank is filled to the brim. This sounds like one (or both) of the level senders is bad. This is strange as it suddenly happened after the last fill up. BTW, I only use Chevron Supreme (which has Techron) in the car so I doubt it is impurities in the fuel.
 

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Discussion Starter · #6 ·
Yup it is test #6. My fuel needle works 5/6 times so I normally just use this test on long trips.
So you are looking at the "actual" levels of each sender, one for each tank? If a sender is bad, how can these be reliable? And how can the individual senders be accurate but the fuel level gauge not be? I realize the OBC averages and filters the sender readings, but unless you are on the track flogging the car around, the average level should still be accurate, especially on a long highway trip.
 

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If you have a "D7" code in Test # 14 (one of the 5 codes which may be listed), you HAVE A BAD left tank sensor. I have no idea what the code would be for a bad right tank sensor. However, these codes have nothing to do with the Peake codes.

I would approach it in a methodical way. First, fill the tank. Check Test # 6, to see if the TOTAL is 65.0 (with 31.0L/34.0R, or 34.0L/31.0R, I just don't remember which, although I think it is the first set). Your tank actually holds 70.0 liters. Watch how the tanks "drain" over time. The right hand tank should stay at it's "full" figure (except on corners), until the left goes dry. Then, the right hand tank level should be reduced over time. You can easily correlate it to the fuel guage over time (3/4 = ~ 52.5, 1/2 = ~ 35.0). Reserve light goes on ~ 10. Ignore the Range as it averages Expected miles/kilometers over the last 20 miles. You should be able to determine if you have a problem with either sensor that way.

Gas will return to a level left/right balance when the engine is off.
 
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In the posts on fuel pumps and fuel gauges, people talk about another "secret menu" displayed via the LED readouts above the steering column (I assume) that is manipulated by the two buttons in the instrument cluster. Which "secret menu" are you guys refering to?
That's the one.

Also, there is nothing in the FAQ above refering to "test #6".
It's on the 2nd page there.
 

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Discussion Starter · #10 ·
If you have a "D7" code in Test # 14 (one of the 5 codes which may be listed), you HAVE A BAD left tank sensor. I have no idea what the code would be for a bad right tank sensor. However, these codes have nothing to do with the Peake codes.

I would approach it in a methodical way. First, fill the tank. Check Test # 6, to see if the TOTAL is 65.0 (with 31.0L/34.0R, or 34.0L/31.0R, I just don't remember which, although I think it is the first set). Your tank actually holds 70.0 liters. Watch how the tanks "drain" over time. The right hand tank should stay at it's "full" figure (except on corners), until the left goes dry. Then, the right hand tank level should be reduced over time. You can easily correlate it to the fuel guage over time (3/4 = ~ 52.5, 1/2 = ~ 35.0). Reserve light goes on ~ 10. Ignore the Range as it averages Expected miles/kilometers over the last 20 miles. You should be able to determine if you have a problem with either sensor that way.

Gas will return to a level left/right balance when the engine is off.
OK. But I thought in earlier posts you state D7 is the code for a bad transfer pump? Or is it an error code that indicates the left tank level is not dropping as it should? In my case a D7 would indicate a RIGHT bad level sensor, because the level would not appear to the computer to be as high as it is, and the OBC may assume the transfer pump is malfunctioning? If its the LEFT sensor, then the system could not detect a defect as the reading would be lower than it actually is. Since the gauge is reading 3/4 with both tanks full, one or both sensors are reading lower levels than they should.

Has anyone posted the resistance ranges known good level sensors produce? Since I know both tanks are full, then I should be able to measure the sensor resistance to find the one that is not reading correctly. If you are correct about gas re-equlibrating between the two tanks, then the resistance readings should be equal with the system off.

Thanks for your help so far.

Also sorted the fuse position out, once I found the 60 Amp fuse position and counted back from there.
 
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