Have a 98 Cobra with an oil pressure gauge that is inop. The sending unit has already been replaced, but the needle still sits at nada.
Any tips or fixes to get this gauge working again?
Any tips or fixes to get this gauge working again?
Oil Pressure Gauge/Sending Unit
- Thread starter Chris.94GT
- Start date
I know on mine, the wire comes off of the sending unit all the time. Fortunately I have an aftermarket oil pressure gauge also.
Perhaps check the for ground at the sender terminal. If you have ground, perhaps you have a break in the wire. If no ground, then it could be a few things; sender bad, NO OIL PRESSURE. Did you use teflon tape when installing it; perhaps you covered the sender with some and it can't get a reading???
Perhaps check the for ground at the sender terminal. If you have ground, perhaps you have a break in the wire. If no ground, then it could be a few things; sender bad, NO OIL PRESSURE. Did you use teflon tape when installing it; perhaps you covered the sender with some and it can't get a reading???
Tape was used, yeah, but the old sender wasn't working either
What about ground at the terminal?
Our oil pressure gauge is just an idiot light in gauge form.
The sender is a simple pressure switch that is open below 6PSI and grounded when over 6PSI. You can check the sender by pulling off the wire and checking to see if the sender terminal is open compared to ground with you engine off and close to zero ohms between the terminal and ground when your engine is running. If it doesn't work this way, you need a new OP switch.
You can test the gauge and wiring to the gauge as well. With the key on, engine off, and the sender wire unhooked, the gauge should read at or below the L mark. Then, with the key on, engine off, ground the sender wire and the gauge should read somewhere in the high-normal range. If it doesn't then you have a gauge or wiring issue.
FYI, in 94-96 clusters, there is a 20 ohm resistor between the oil pressure signal and the gauge. That resistor limits the needle movement to high-normal. Without it, the gauge will slam to way over the H when the engine is running. 97 and 98 clusters have a different gauge that will not slam over H when the signal is grounded, so they could eliminate the resisor.
The sender is a simple pressure switch that is open below 6PSI and grounded when over 6PSI. You can check the sender by pulling off the wire and checking to see if the sender terminal is open compared to ground with you engine off and close to zero ohms between the terminal and ground when your engine is running. If it doesn't work this way, you need a new OP switch.
You can test the gauge and wiring to the gauge as well. With the key on, engine off, and the sender wire unhooked, the gauge should read at or below the L mark. Then, with the key on, engine off, ground the sender wire and the gauge should read somewhere in the high-normal range. If it doesn't then you have a gauge or wiring issue.
FYI, in 94-96 clusters, there is a 20 ohm resistor between the oil pressure signal and the gauge. That resistor limits the needle movement to high-normal. Without it, the gauge will slam to way over the H when the engine is running. 97 and 98 clusters have a different gauge that will not slam over H when the signal is grounded, so they could eliminate the resisor.
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It is working now. There are two different senders available, one with light and one with gauge. Apparently on 98's, the sender for light will not work.
Had this problem with mine and meant to do a posting on it awhile ago. I know this doesn't make any sense, but the sending unit for the 98 GT is what worked for me. I bought the one for my '98 Cobra and it deadlined as well. I can't remember why I went with the one for the 98 GT but it worked. As many have said the '98 Cobras are bastards due to the 99 changeover.
I saved both boxes but I am not sure which one is NOT for the Cobra but that is the one that actually worked:
Motorcraft Part
SW-1311
D4AZ-9278-A
Motorcraft Part
SW-2220
E9SZ-9278-A
do you recall which part number you used?
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Late to the thread; I have some oil pressure switch part numbers in the link in my sig as well (not sure if it's '01 specific info though; maybe it will assist others using the search feature though).
Thanks.:beer:
Its funny when you stumble on your own post when searching for an answer. I verified that the 98 GT sending unit it the SW-2220 and this is the one that worked on my '98 Cobra which is a late '98, born 06-18-98. Hopefully this helps. As of today, Rockauto.com has the Motorcraft sending unit for $12.39.
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