Strange Oil Gauge Issue | Ford Explorer Forums - Serious Explorations

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City, State
Bonita Springs, FL
Year, Model & Trim Level
2000 XLT, V6 OHV
My oil gauge is going crazy lately when I accelerate and moves a bit at idle. This has happened before because my original oil switch broke. But after replacing it the problem went away. That was a few years ago.

This time my oil gauge is going crazy but only when my battery gauge is low.

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I’m not sure how the two are related but when the battery gauge is back to normal the oil gauge is too.

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The only thing I can think of is that the wire that goes to the oil switch is damaged and somehow draining the battery faster than the alternator can charge it, without burning a fuse. I checked the battery and it’s at 12.5 volts when the engine is off.
 



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You have a charging issue. No way you could be leaking that much current to ground without starting a fire.
 






You have a charging issue. No way you could be leaking that much current to ground without starting a fire.
I’ll have to test the alternator this weekend. I wonder why the oil gauge is acting up but it may just be a very rare coincidence.
 






It’s because your voltage is low. I wouldn’t be surprised if it’s not shifting 100% correct either.
 






You can measure the voltage while the engine is running to see if it's up around 14.(n)V where it should be.

If voltage is good then I would suspect a bad wire or connector (or trace on) the gauge cluster.

However if mostly happening when accelerating, I'd wonder if you have a stretched belt and/or worn out belt tensioner causing the belt to slip.
 






You can measure the voltage while the engine is running to see if it's up around 14.(n)V where it should be.

If voltage is good then I would suspect a bad wire or connector (or trace on) the gauge cluster.

However if mostly happening when accelerating, I'd wonder if you have a stretched belt and/or worn out belt tensioner causing the belt to slip.
I’ve replaced the belt and tensioner recently so that should be ok. I pushed down on the connector yesterday and the problem hasn’t come back. So it’s probably terminal corrosion causing the issue.
 






Some connectors have an insert in the back that you can pull out to release the contacts to more easily clean them.
 






So now I’m having trouble starting. I’ll get the classic fender click when I turn the key forward. I crawled under the truck and banged on the starter hoping it would start but no luck. So I disconnected and reconnected the alternator wiring and bam, it’s started right up.

I’m slowly narrowing down the issue. Just trying to figure out if the alternator connector competes some circuit that keeps the truck from starting, if it’s not making a good connection.
 






Alternator does not play any role according to the attached diagram.

A click but not engaging, usually means insufficient power due to weak battery (could be weak due to alternator not charging it rather than battery itself "bad"), wire/connector corrosion, positive or ground. Or of course bad solenoid. You could try swapping the starter relay with another of same type. You can measure voltage at the starter battery cable lug while a helper is turning ignition key to see if drooping too low when it clicks.
 

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The voltage issue (now low low you can't start) will make your oil pressure gauge (analog idiot light) move around. The factory oil pressure switch is just that, a switch. When there is pressure it closes the circuit and there is a resistor in the circuit of the oil pressure gauge so it'll read in the middle (20 ohms IIRC). The earlier 2nd gen's have an actual resistor on the back of the cluster PCB while the newer ones have it built into the gauge. If you jump over the resistor on the back and put in a real oil pressure sending unit (the bigger/bell looking one for older Fords) your oil pressure gauge will read like a real gauge and move with the pressure.

Once you have your voltage/charging issue figured out look into the oil pressure switch to oil pressure gauge conversion: How to: Make Oil pressure gauge perform like "real" gauge

~Mark
 






I had my battery checked and it had 920 CCA and the alternator was charging it fine also. I’ll check relays next as most of them are original. I’ll look into the oil switch conversion but I’m not looking forward to it as I’ve already had the dash apart twice in the last month replacing bulbs 😁
 






I would go through and clean all the battery and all ground connections clean and shiny and tight.

Battery positive line to the distribution box then to the alternator.
Main ground to the starter bolt stud.
PCM ground 2 wires located on the firewall.

Ground from the engine head to the firewall by washer motor, little braided strap. both ends.
Ground on core support from battery.
ground beside battery.
ground behind coolant reservoir.

There is also braided strap grounds from frame to body underneath on both sides.

This cheap maintenance.

DR
 






Sounds like the slip ring in the alternator is getting near its end of life. Replace the alternator now before it leaves you stranded somewhere.
 






Ditto, something is up in the charging circuit, and it's affecting the oil pressure gauge at times.

While driving, at any stop light, watch the voltage gauge, and gently raise the idle to about 1000rpm. If the gauge pops up a little with the slightly higher rpm, the alternator is having trouble making enough juice at idle in gear.
 






I cleaned the battery posts, all the battery cable connectors down to the starter, and the mega fuse contacts and the issue went away. I have normal charge now. Thanks to everyone for the input and hopefully this post helps someone out in the future.

I replaced the alternator a few years back with a Bosch unit (still going strong) so I should be ok there. The battery posts were dark so I’m sure that was affecting the ground. The mega fuse was also very corroded and the contacts on it look like new again. A wire brush and dremel cleaned everything up.
 






Excellent. The main battery and power cables are critical items that with age need that kind of special attention. Those are the next thing to look at after checking voltages for starting issues.
 






Look for any green oxidation around the cables i.e... starter, battery, ground, and ground straps. Also, the brushes may be sticking on the voltage regulator causing it not to make contact with the slip ring. You can remove the black cover on the back of the alternator then remove the VR and inspect it.
 






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