{Chrysler 300} Re: Oil pressure sender / gauges , 1960 up

[John Grady <jkg@xxxxxxxxxxxxxxxxx>]

Actually —I don’t understand what you see , unless end of wire was accidentally touching metal -

Actual default open circuit on the wire  to gauge from sender  is a low side reading —-gauge would not move or only slightly . If it goes high with sender  not connected you have a short to ground on that wire . 

Disconnect sender wire at the gauge , see if it then stays low when turned on.— Then it is short in wiring . —-if it still goes high , short May be in gauge , that fine wire off the heater winding to sender terminal may be touching metal box of gauge (if that happens), or was  burned in past which lets it touch the metal strip it is wound on —  ( point is you can sometimes fix it ) . I have not seen shorted senders but possible ( goes incorrectly high only when connected) 

Don’t adjust gauge settings , / calibrations very easy to screw it up . No reason that could ever change . 

Fast way to test oil , temp and tank is disconnect a wire right at a sender , the gauge should not move with wire off  . Then briefly short wire still not connected to sender to ground —-gauge should go up to high or beyond high .
That tests everything but sender and regulator .. 

A good test of regulator and also for an open wire , put an analog *12-15v voltmeter on the lead to ground while off the sender , you should see pulsing 12 v about one per second . If you do the mechanical regulator is good and working , and wire is not open . Steady 12 is stuck regulator or no ground at gauge cluster  . Open wire or no power to gauges you see nothing . 

If all this is ok , probably sender . It ( all of them ) read about 75-90 ohms or more not activated or empty tank  .(but not open    —over say  200  )  They all drop to about 10 ohms for full scale of gauge .
If one or two gauges work right and one does not it cannot be the  regulator .( amp not included) . Also if you watch gas needle carefully when ign first turned on , you can see the little steps as it moves up . That is the regulator pulsing . 


If  Regulator inoperable ( 12v on all the time , no pulse) = gauges all way  high ,it  is often poor ground of the metal frame the gauges mount to , run   wire from screw to good ground . This 12 v steady can burn out all 3 gauges , watch out . 
Hope this helps—-kind of  first troubleshooting step on gauges .

Related —Chinese fuel senders sold by Vans others are not calibrated right but often we have no choice . So move the arm outside tank , running sender on two clip leads  maybe bend it to reach bottom try to get E right , —-you can live with an error on F  . Also ford brass fuel tank floats are cheap ,  I attach to old  mopar rod (if  bad float) with 14 or 12  solid copper wire soldered to   (Has to be shiny ) mopar rod . Can solder copper  ( very quickly) to little tank or wrap copper in groove , easy to bend too . 
Same thing on replacement temp senders sold for our cars don’t track well , read incorrectly — keep old ones or pull one off junk motor . 60 62 , probably same later to ~70 ok , pre 60 wire wound 12v gauges are different values. 
Oil sensors  seem ok . 
John g
* digital meters cannot track pulses —-hard to tell what is going on . Numbers jump all around . Analog little one cheap at Home Depot . 
Sent from my iPhone

> On Oct 29, 2022, at 11:52 PM, D.C. Mason <petergriffinforpresident@xxxxxxxxx> wrote:
> 
> Thanks John.  I was getting no reading at all on the 61 astrodome oil gauge while running the car.  Disconnected the wire at the sender and the gauge went all the way right (high) - must be default open circuit behavior.  Removed sending unit and connected oil pressure gauge in its place.  Was getting almost 50psi at idle.  So at least there is actually oil pressure.  Electrical issue possibly in sending unit.  I may try and see if Napa carries them for 60-62 and just replace it.  
> 
> V/r
> dave
> 
> Sent from my iPhone
> 
>> On Oct 29, 2022, at 7:31 PM, John Grady <jkg@xxxxxxxxxxxxxxxxx> wrote:
>> 
>> 90 sounds right , the fuel tank sender is 90 or so on E , about 10 on F . the gauges are identical inside  , so 90 would  read right at low end of oil scale .
>> Oil not as critical as fuel ! 
>> 
>> Sent from my iPhone
>> 
>>>> On Oct 29, 2022, at 1:15 PM, D.C. Mason <petergriffinforpresident@xxxxxxxxx> wrote:
>>> 
>>> Ooops oil pressure sender, rather…
>>> 
>>> Sent from my iPhone
>>> 
>>>>> On Oct 29, 2022, at 1:10 PM, D.C. Mason <petergriffinforpresident@xxxxxxxxx> wrote:
>>>> 
>>>> Hi John,
>>>> 
>>>> Do you happen to know what the static ohms should read for our engines switches?  Guessing they are the same but it’s for a 61.  Measured two and one read 24.6 and the other 93.9 ohms….
>>>> Thanks!
>>>> dave
>>>> 
>>>> Sent from my iPhone

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