Re: {Chrysler 300} Temp Gauge issues

On Wed, Mar 1, 2023 at 11:59 AM John Grady <jkg@xxxxxxxxxxxxxxxxx> wrote:

First , all this applies only to wound coil type
gauges ( they move up fast at turn on ) Don’t use this info directly on later thermal gauges) . Thermal take a few seconds to move up

if jumping around , it can be a loose or corroded wire —most likely , — especially right at the temp sender ( broken inside fitting or loose fit )
To troubleshoot fully * put an analog voltmeter on + dc power at gauge , leave on floor if it jumps when gauge does , trace back the power lead . if ok , steady 12 , move the analog meter + lead to gauge terminal on back of gauge .
If wire or the sensor itself opens up it will jump full scale to 12 , (?= open circuit to gauge then — it grounds variably through the sender ) Normal reading is somewhere in middle . If v meter drops to zero (and gauge goes to hot) , the wire is shorting to ground somewhere . If meter drops to zero and gauge goes to C , there is an intermittent open in the gauge itself , no power is coming out to sender .
To separate wire issues from the sender , repeat same test by extending a wire from right at sender , or just unplug sender , gauge should stay on C , drive around ( if it jumps to H , you have a wire short ) Then short wire to ground solidly with clip lead, gauge should stay on H . If that happens , wire and gauge is ok , ( * can do this first too , —- might save time ) ; success on this indicates sender is bad ( loose connection inside ? ) Beware —- senders sold to fit our cars are usually wrong ohms , some kind of Chinese universal . Scale will be off . Like gas tank units . Try to pull one off a junk motor or junkyard . any 56-59 mopar
probably same .
Sometimes needle mechanically sticks or goes too far toward C ( or E) ( need to add a stop) and it sticks there , no electric issue existed at all . Go over a bump you look down today it is working ! This really baffled me once , i think mr Meritt wrote that up in tech .

hope this helps ..
John G
Sent from my iPhone

On Feb 28, 2023, at 10:49 PM, 'John Lazenby' via Chrysler 300 Club International <chrysler-300-club-international@xxxxxxxxxxxxxxxx> wrote:

I'm forwarding this for club member Mike Hassenplug who lives in Kansas. He is not able to post on the list server. Bob Merritt, I've also sent this to you so that you can add Mike to the server.

I'm not that versed on electrics. Here is Mike's post to me.

The needle on my temp gauge on my 300 B jumps around like a rabbit on meth. Sometimes on the highway, it'll settle down and perfprn properly, but it'll go back to being spastic again. I suspect a wire, but the wire from the temp sensor appears ok, and it appears to go to the generator. Can you refer me to someone who could help?

John Lazenby

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