Gas Gauge Failure. . .How to fix...Thank you, Brian (69 Pace) - Page 4 - Team Camaro Tech
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post #46 of 103 (permalink) Old Jul 30th, 13, 11:04 PM
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Re: Gas Gauge Failure. . .How to fix...Thank you, Brian (69 Pace)

I found a picture you posted in another thread (below). It's pretty much the same angle/view as my picture too. The wires shown in this pic are completely different colors than mine.

Green left, Red Right, black center.

Seems like I should just get a new module. You said there is a variable setting version...who sells that?


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post #47 of 103 (permalink) Old Jul 31st, 13, 04:35 AM
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Re: Gas Gauge Failure. . .How to fix...Thank you, Brian (69 Pace)

This might help: Diagram shows the 'wire side' of the gauges.

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post #48 of 103 (permalink) Old Jul 31st, 13, 10:17 AM
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Re: Gas Gauge Failure. . .How to fix...Thank you, Brian (69 Pace)

Quote:
Originally Posted by Everett#2390 View Post
This might help: Diagram shows the 'wire side' of the gauges.
Hmmm. cool diagram, thanks! I can't quite make out the "colors" of the Low Fuel wiring. Or if it matters which side the colors go to on the gauge.

Actually, I notice there is no "polarity" for any of the connections. Does it not matter?

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post #49 of 103 (permalink) Old Jul 31st, 13, 10:39 AM
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Re: Gas Gauge Failure. . .How to fix...Thank you, Brian (69 Pace)

Didn't read the entire thread, but if your using the 86 ohm resistor that you posted a picture of yesterday on your gas gauge, you've got the wrong resistor. Gas gauge uses a 45 ohm resistor, temperature gauge uses and 86 ohm resistor. Using a resistor with higher resistance than normal will make the guage read higher than it should, which appears to be what yours is doing.

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post #50 of 103 (permalink) Old Jul 31st, 13, 11:58 AM
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Re: Gas Gauge Failure. . .How to fix...Thank you, Brian (69 Pace)

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Originally Posted by Mark C View Post
Didn't read the entire thread, but if your using the 86 ohm resistor that you posted a picture of yesterday on your gas gauge, you've got the wrong resistor. Gas gauge uses a 45 ohm resistor, temperature gauge uses and 86 ohm resistor. Using a resistor with higher resistance than normal will make the guage read higher than it should, which appears to be what yours is doing.
Well...looks like I'll have to pull the temp resistor and check it too.

If the resistor for the gas gauge is wrong...wondering why I've gone all the way to the empty mark without running out of fuel?

It appears everything in my console is original and never messed with. I only pulled it out 20+ years ago when the car was painted..and I only disconnected the harness...nothing on the fuel module was disconnected by me back then. Who knows though...two other owners had the car for 24 years before me.

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post #51 of 103 (permalink) Old Jul 31st, 13, 01:20 PM
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Re: Gas Gauge Failure. . .How to fix...Thank you, Brian (69 Pace)

Here is a drawing of how my LFWM was wired. Colors are representative of actual colors on the module.


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post #52 of 103 (permalink) Old Jul 31st, 13, 08:45 PM
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Re: Gas Gauge Failure. . .How to fix...Thank you, Brian (69 Pace)

Quote:
Originally Posted by MMMM_ERT View Post
Well...looks like I'll have to pull the temp resistor and check it too.

If the resistor for the gas gauge is wrong...wondering why I've gone all the way to the empty mark without running out of fuel?


It appears everything in my console is original and never messed with. I only pulled it out 20+ years ago when the car was painted..and I only disconnected the harness...nothing on the fuel module was disconnected by me back then. Who knows though...two other owners had the car for 24 years before me.
Wait a second I didn't say the resistor was wrong, if you tested the resistor naked (as in removed from the gauge) then the reading you got is correct! 86 to 89 Ohm's.

Just reconnect it to the gauge, tighten down the nuts and test through the posts again and it should read 43 to 47 Ohm's depending on age and number of turns.
Trust me on this one you more then likely have the correct resistor card.


It is the wiring of the LFWM that puzzles me. if you hold the module with the wires at noon, the wires are in two groups of two coming out of the back the first wire on the right should be the true yellow that connects to the harness to trigger the dash light. Next is the black ground for the middle post. Next heading to the left is the red hooked to the right post of the gauge and last is the green hooked to the left post of the gauge.

So I think if you wire yours like that and test you should have no dash light at 3/4 full. The trigger point will be someplace in the 20 to 8 Ohm's range. You can test with the 0 to 100 Ohm potentiometer from Radio Shack. Set the knob with your meter to 20 and test sending the output tot he gauge like the sender would then turn the knob until the dash light goes on, then read with your meter to know the actual set point of your module. Everett has posted the directions for using this tool before but my search is crippled tonight after working back to back double shifts.

The variable unit is manufactured by M & H electric and is listed as replacement "adjustable" low fuel warning module. M & H Adjustable set point Low Fuel Warning Module

When I was talking about the gauges, I had the gauge pod, back side facing up, and oil and fuel on the bottom row, oil on left fuel on right.



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post #53 of 103 (permalink) Old Jul 31st, 13, 09:31 PM
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Re: Gas Gauge Failure. . .How to fix...Thank you, Brian (69 Pace)

Quote:
Originally Posted by 69-Pace View Post
Wait a second I didn't say the resistor was wrong, if you tested the resistor naked (as in removed from the gauge) then the reading you got is correct! 86 to 89 Ohm's.

Just reconnect it to the gauge, tighten down the nuts and test through the posts again and it should read 43 to 47 Ohm's depending on age and number of turns.
Trust me on this one you more then likely have the correct resistor card.


It is the wiring of the LFWM that puzzles me. if you hold the module with the wires at noon, the wires are in two groups of two coming out of the back the first wire on the right should be the true yellow that connects to the harness to trigger the dash light. Next is the black ground for the middle post. Next heading to the left is the red hooked to the right post of the gauge and last is the green hooked to the left post of the gauge.

So I think if you wire yours like that and test you should have no dash light at 3/4 full. The trigger point will be someplace in the 20 to 8 Ohm's range. You can test with the 0 to 100 Ohm potentiometer from Radio Shack. Set the knob with your meter to 20 and test sending the output tot he gauge like the sender would then turn the knob until the dash light goes on, then read with your meter to know the actual set point of your module. Everett has posted the directions for using this tool before but my search is crippled tonight after working back to back double shifts.

The variable unit is manufactured by M & H electric and is listed as replacement "adjustable" low fuel warning module. M & H Adjustable set point Low Fuel Warning Module

When I was talking about the gauges, I had the gauge pod, back side facing up, and oil and fuel on the bottom row, oil on left fuel on right.

Okay...clear on the resistor.

The wires are different colors on my module than you are describing and were hooked up as in my diagram (post 51) above. ...and the fuel light never comes on. It only came on once after my meltdown that started this whole thing.

Here is a closer look, see the colored arrows touching the wires.

If looking at the module at 12 O'clock:

1st set
light yellow - farthest left is connectetd to left stud looking toward back of car
red -2nd to the right is connected to the right stud looking toward back of car.

2nd set
Bright yellow - 3rd to the right goes to trigger connector
brown - 4th and farthest right is gnded to center stud (see diagram in post 51 above)


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post #54 of 103 (permalink) Old Jul 31st, 13, 10:00 PM
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Re: Gas Gauge Failure. . .How to fix...Thank you, Brian (69 Pace)

BTW...did you use that module from M & H?

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post #55 of 103 (permalink) Old Jul 31st, 13, 10:51 PM
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Re: Gas Gauge Failure. . .How to fix...Thank you, Brian (69 Pace)

AFter searching like a madman...I can't find a way to test the module out of the car. I can't do the test Brian mentions above...all my power is disconnected while I'm working in the console. One smoulded wire set was enough to cure me from working with live power.

So... is there a way to test the module out of the car?

Also...I found this post: do you think these gauges still function? (pictures)

The plot thickens...It seems my module is a 1969 module.. with white circuit board. Mine also has the same color wires as the one in the images from that post.
Bright yellow trigger, light yellow, darkish red, and a brownish.

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post #56 of 103 (permalink) Old Aug 1st, 13, 12:41 AM
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Re: Gas Gauge Failure. . .How to fix...Thank you, Brian (69 Pace)

Sorry to keep bombing you guys.

Now i"m completely confused.

This site says 67, 68 and 69 low fuel warning modules are all different and not interchangeable.

http://www.americanautowire.com/view...ndicator-work/

Yet everyone sells one module for both years 68/69. What gives?

I also got to thinking...if my module ISN'T bad...
My fuel light has never come on under normal circumstances and I've run my GAUGE down to "E". I only ever put 15 gallons in at the most...and it's an 18 gallon tank ...perhaps the gauge is reading wrong. I tested the sender and was getting 56 Ohms with a little under 3/4 tank per the gauge. I unplugged the sender wire and turned on the key...needle went past "F". Then I GND'd the sender wire and the gauge dropped to "E" but not past.

I'm tired and heading to bed!

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post #57 of 103 (permalink) Old Aug 1st, 13, 04:02 AM
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Re: Gas Gauge Failure. . .How to fix...Thank you, Brian (69 Pace)

Quote:
Originally Posted by MMMM_ERT View Post
BTW...did you use that module from M & H?
No did not or have not as of yet. I purchased an entire new gauge pod because after a buddy s oil line to his gauge failed, and the same thing had happened in a matter of weeks to a member here I intend of having the oil gauge converted to an electronic receiver/sender setup and wasn't going to modify the original gauge set. Once that comes back and is installed I'll see what the reproduction set point is - experience shows it is 1/4 tank which is ok for me. But time will tell. M & H is a top notch shop so the module is built well and is regarded highly in the Corvette world as far as I could find in their forums.


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post #58 of 103 (permalink) Old Aug 1st, 13, 04:15 AM
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Re: Gas Gauge Failure. . .How to fix...Thank you, Brian (69 Pace)

Quote:
Originally Posted by MMMM_ERT View Post
AFter searching like a madman...I can't find a way to test the module out of the car. I can't do the test Brian mentions above...all my power is disconnected while I'm working in the console. One smoulded wire set was enough to cure me from working with live power.

So... is there a way to test the module out of the car?

Also...I found this post: do you think these gauges still function? (pictures)
You can bench test using a 12 volt power supply from Radio Shack or a "powerprode" testing tool. Or just buy a new module and call it done

Quote:
Originally Posted by MMMM_ERT View Post
The plot thickens...It seems my module is a 1969 module.. with white circuit board.
1967 is a different unit design since it needs to power the dash light. 1968 and 1969 console gauge pacs and modules are BOTH the same as it grounds the fuel light which gets it's power through the dash circuits. The only difference is how the ground gets to the dash light. 68 it hits the pin connector since the inst panel lights are controlled by printed circuit - 69 it goes straight to the dash bulb.

Quote:
Originally Posted by MMMM_ERT View Post
Mine also has the same color wires as the one in the images from that post.
Bright yellow trigger, light yellow, darkish red, and a brownish.
Okay - but when I look at the posted picture I see Green, Yellow, Red and Black wires on the module. The green is a lighter green but it looks green to me and it is connected to the left side post of the gauge. So maybe brownish is the black to the middle and red to the right post of the gauge


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post #59 of 103 (permalink) Old Aug 1st, 13, 04:20 AM
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Re: Gas Gauge Failure. . .How to fix...Thank you, Brian (69 Pace)

Quote:
Originally Posted by MMMM_ERT View Post
Sorry to keep bombing you guys.

I'm also got to thinking...if my module ISN'T bad...
My fuel light has never come on under normal circumstances and I've run my GAUGE down to "E". I only ever put 15 gallons in at the most...and it's an 18 gallon tank ...perhaps the gauge is reading wrong. I tested the sender and was getting 56 Ohms with a little under 3/4 tank per the gauge. I unplugged the sender wire and turned on the key...needle went past "F". Then I GND'd the sender wire and the gauge dropped to "E" but not past.

I'm tired and heading to bed!
I'm assuming that until it is hooked up correct it could never read the sender output and react by lighting the light. So it is highly possible the module is okay. Night


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post #60 of 103 (permalink) Old Aug 1st, 13, 09:11 AM
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Re: Gas Gauge Failure. . .How to fix...Thank you, Brian (69 Pace)

I'm going to take the module to work and have one of our EE's test it. We have all sorts of test equipment. Just don't want to spend $60 on a module without confirming mine is bad.

As for the wiring in the car...It appears mine was hooked up correctly. The only real difference we're talking about is what you see as green is light yellow to me. Perhaps I'm going color blind!

Brian you (and others) have been a huge help...I very much appreciate it. Wish I could buy you guys a beer or two.

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