This one will probably be a top of the head answer for some but... I have an electric oil pressure sender (one wire) that works a "pressure" guage. The guage is not working and I wish to put my $6 multi-meter tester to work. How do I do this to see if the sending unit is bad (and yes I have oil and it is being distributed through the engine nicely )

Thanks all, --Mike

 

Hello Mike G, If you are the one and the same who answered me rjs_korea, thanks and maybe I can help you. If I am not mistaken the oil pressure sending unit is quite like your gas tank sending unit (the resistance changes) but instead of a moveable arm it has a small diaphram that canges resistance as the pressure changes. I would imagine that the more pressure the more resistance or vice versa. If you play with the meter, turn it to "OHMS", make sure the leads are plugged into the correct recepticle on the meter and touch the leads firmly together, the needle should swing to zero or the display should read zero if it is a digital meter. Then with the sending unit out of the vehicle, touch one lead to the terminal and the other end to the threaded portion. If the needle moves to a lower value than the open circuit resistance ( when the leads are apart) you will read the resistance. If it doesn't move then it is "open." To be sure go the nearest auto store and ask to check a "known good one" which was made in Malaysia or Mexico or Indonesia, and compare. The people in those stores are usually quite friendly and will let you do it and marvel at your adeptness. Better yet go and put the new one in and try it they are very cheap.

 

Mike.
Keep all test voltage below 5V if you're using voltage in any of your guage systems.

I'd check your CVR first to be sure it's working. CVR stands for Constant Voltage Regulator and it feeds your instrument panel. If the CVR is good you can "reverse" test your sender by ruling out your guage as any contribuiting cause.

Full Ground should = full pressure, or highest reading, but you do not need to "hold it on" just touch ground to sender side of guage. If gauge good needle should begin to swing upward. Needle swing is enough to validate a gauge. If/ when needle swings upward, gauge is good. Move on to sender and/ or wiring. I agree with rjs, if CVR & Gauge check out OK purchase new oil pressure sender unit & install it.

I also have gauged instruments. I use and reccomend using Motorcraft, Echlin (NAPA Brand) or another well known reliable Mfgrs' sender unit. Avoid national discount auto parts franchise & house brands. I've gotten "burnt" using "off" Brands on apps requiring accurate & true readout or performance. I've had Wells relays in EFI systems "drive me off the end of the pier" or worse, work a week, or 10 days & lay down, stranding my client. There's usually no recourse on electrical parts so I've had to "eat the cost" as well as soothe an angry client...not good!

It's a bummer when you have to make good on something you just repaird a week or two before when it's not of your doing, and hte fault of shoddy parts. People think I'm stupid or something. They just don't understand really.

FWIW don't insulate your new sender with mylar tape or thread compound, when you install it run it in dry so it has a clean connection.
CIAO
FBp

 

Wonderful insight fella's, forgot about the CVR, had one of those little buggers give me fits on the wife's Cougar in the past.... I can't wait to get to testing.

GRAZIE, --Mike