Help! Gauge Needles "swing" strangely - '68 Polara
06-10-2009, 03:54 PM
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Help! Gauge Needles "swing" strangely - '68 Polara
The needles on the Fuel Gauge & Temperature Gauge began "swinging"
(IE: Repeatedly moving from a low reading to a higher reading within a couple seconds)
towards the end of a couple-hours long, 130 mile journey.
They did not "swing" like this earlier the same day, or ever before..
It was like they were going back to "zero" then swinging up to their "normal" readings.
Only the Fuel and Temp Gauges were doing this, the Alternator Gauge was rock-steady.
What could be causing this?
Loose ground wire or instrument cluster wiring..?
I doubt two seperate sending units and/or gauges would go bad simultaneously lol
(and the car was running flawlessly otherwise).
(IE: Repeatedly moving from a low reading to a higher reading within a couple seconds)
towards the end of a couple-hours long, 130 mile journey.
They did not "swing" like this earlier the same day, or ever before..
It was like they were going back to "zero" then swinging up to their "normal" readings.
Only the Fuel and Temp Gauges were doing this, the Alternator Gauge was rock-steady.
What could be causing this?
Loose ground wire or instrument cluster wiring..?
I doubt two seperate sending units and/or gauges would go bad simultaneously lol
(and the car was running flawlessly otherwise).
06-10-2009, 04:17 PM
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Hard to tell exactly what this connector is but both of these wires pass through it.http://www.mymopar.com/downloads/196...araMonacoA.JPG Look at the wire for the temp and fuel guage and they both come off this connector, the round looking one. I'll bet that when you have this problem, that connector is feeling hot .It looks like a main plug for the back of the instrument cluster
Last edited by scotts74birds; 06-10-2009 at 04:19 PM.
06-10-2009, 05:58 PM
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I think you both have valid theories..
And thank you for posting that partial wiring diagram!
I took 'er out for a drive today,
got 'er up to operating temperature,
cruised around a bit and no gauge swinging noted.
So at this point it may be just an intermittant bug
(knock on wood).
If it re-occurs I'll investigate behind the instrument cluster..
And thank you for posting that partial wiring diagram!
I took 'er out for a drive today,
got 'er up to operating temperature,
cruised around a bit and no gauge swinging noted.
So at this point it may be just an intermittant bug
(knock on wood).
If it re-occurs I'll investigate behind the instrument cluster..
06-10-2009, 06:08 PM
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Yes, but my theory is validerer
Just kidding polaradue! Couldent get the other pic for you. But it has the same link and its called MonacoB thats for the front harness. http://auto.howstuffworks.com/fuel-gauge1.htm This shows how a fuel gauge works and will help you understand whats going wrong. Temp gauge works on the same theory.
Just kidding polaradue! Couldent get the other pic for you. But it has the same link and its called MonacoB thats for the front harness. http://auto.howstuffworks.com/fuel-gauge1.htm This shows how a fuel gauge works and will help you understand whats going wrong. Temp gauge works on the same theory.
06-10-2009, 07:07 PM
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(can't get that "MonacoB" page to come up..)
Check THIS out - an article on the subject,
with a fix for the problem too..
http://www.allpar.com/history/mopar/electrical2.html
Check THIS out - an article on the subject,
with a fix for the problem too..
http://www.allpar.com/history/mopar/electrical2.html
06-10-2009, 07:16 PM
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Great article. I'll be putting that in my playbook also, thanks. These are very common problems with older Mopars, and I suggest anyone reading this thread to bookmark these last two links. Theres a lot of learning to be had here. Thanks 68
06-10-2009, 09:18 PM
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The needles on the Fuel Gauge & Temperature Gauge began "swinging"
(IE: Repeatedly moving from a low reading to a higher reading within a couple seconds)
towards the end of a couple-hours long, 130 mile journey.
They did not "swing" like this earlier the same day, or ever before..
It was like they were going back to "zero" then swinging up to their "normal" readings.
Only the Fuel and Temp Gauges were doing this, the Alternator Gauge was rock-steady.
What could be causing this?
Loose ground wire or instrument cluster wiring..?
I doubt two seperate sending units and/or gauges would go bad simultaneously lol
(and the car was running flawlessly otherwise).
(IE: Repeatedly moving from a low reading to a higher reading within a couple seconds)
towards the end of a couple-hours long, 130 mile journey.
They did not "swing" like this earlier the same day, or ever before..
It was like they were going back to "zero" then swinging up to their "normal" readings.
Only the Fuel and Temp Gauges were doing this, the Alternator Gauge was rock-steady.
What could be causing this?
Loose ground wire or instrument cluster wiring..?
I doubt two seperate sending units and/or gauges would go bad simultaneously lol
(and the car was running flawlessly otherwise).
It's a little silver box about an 1 1/2" long 1/2" wide behind the dash, esay to fix, replacement should cost less than $10 at NAPA
06-10-2009, 09:35 PM
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Please recheck the post from 68 Polara at 10:07 for a modification to this that can save folks alot of grief. Its one of the best info links ive seen for us.
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