Oil Pressure Gauge Stuck at 90 psi
 

The second the gauge gets power from ignition (before cranking the car) it just pegs out at 90 psi, and doesn't budge. It stays like this while driving too.

What I've checked:

• Pulled the wire off the oil pressure sender - gauge drops to 0 psi
• Checked resistance at the pressure sender expecting perfect continuity - No.. normal 45-50 ohms at idle, and 180 ohms when engine is off.
• Plugged the wire back into the pressure sender - gauge pegs its self at 90 again.
• Pulled the gauge for a visual inspection. Everything looks fine, but I have no resistors on hand to test it out.

I'm not great with electrical, but my best guess is that the coil inside the gauge has shorted causing the gauge to read as though there was no resistance. Does this sound legit?

I'm hoping someone else might be able to point me in the right direction here. I've read I can use a resistor to check the gauge, but I'm not sure how to go about testing it once I get one. Any help would be awesome!

Hope I got this in the right forum.

Check resistance at gauge cluster?
Make sure it matches that of the pressure sender

Thanks Gryff. I'll give it a shot. What are you thinking could cause different readings at the cluster? I just assumed that if it was shorted to ground, the gauge wouldn't drop to zero when I unplugged it from the sender.

It my understanding that the oil guage is either on or off much like an" idiot light". You can get a kit to upgrade to an actual oil pressure guage. I don't have a link to one at this time. I will try to post one when I get jome if I remember.

What kind of gauge is this? The stock gauge? aftermarket? I am assuming aftermarket since you are saying 90 PSI.

You need to get a known resistor within the gauge's measurement range and test the gauge.

http://www.dommelen.net/miata/goodies/oil.htm

The above link is some info I found. I don't know what year model you have, but I hope this helps. At the very least, it has links @ the bottem of the page to buy parts.

Stop being a lazy fuck and search for your answer.

Lol, trying to fit in?

For the rest who have responded, thank you! Sorry for the lack of info up front. My car is a 1994, and the gauge and sender are stock. 90-94 year models had a true oil pressure gauge. The sender reads 0-180 ohms with 0 being 90 psi on the gauge, and 180 being 0. It's a popular mod to replace the later on/off idiot gauge with the earlier one my car came with. However, it makes finding cheap parts difficult since they're in such high demand. On the upside, at least the info is readily available about how to access the sender and gauge, even if I have found very little about troubleshooting the system.

I recently ordered a gauge on Ebay. I'll be dropping it in when it arrives, and will report back

Thank you everyone who had something to offer. I installed the new(used) gauge today, and it works like a champ. My best guess is that something in the gauge shorted to ground causing it to read as though there was no resistance (90psi)


/solved!

Do you have aftermarket gauge faces?

Nope. The previous owner was a girl who I don't think cared to modify anything. I still have the flower pattern floor mats to prove it! lol

Good stuff you got it working, and replied back with the solution.

It gets old when members open a thread about a problem and simply ghost out and continue with other threads without providing any follow up.

What brand/model did you end up buying?