Gauge cluster testing
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Elder User
Joined: Oct 2003
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From: Seattle
Gauge cluster testing
I was thinking about this during my last oil change.
How would I know if a gauge was reading incorrectly?
On my 2000 Ranger I have 4 gauges - Gas, Oil pressure, Water temperature, and alternator. Of all those gauges, only the gas gauge ever moves.
So what if one of those gauges was wrong or perhaps not even reading at all? Is there some sort of quick test I can do every so often to verify that the gauges are displaying accurate information?
How would I know if a gauge was reading incorrectly?
On my 2000 Ranger I have 4 gauges - Gas, Oil pressure, Water temperature, and alternator. Of all those gauges, only the gas gauge ever moves.
So what if one of those gauges was wrong or perhaps not even reading at all? Is there some sort of quick test I can do every so often to verify that the gauges are displaying accurate information?
Posting Guru
Joined: Nov 2003
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From: Homer, Alaska
I think these guages are not real accurate, but act more like indicators or the idiot lights. Some quick tests would be:
1. Alternator-check voltage engine off-should be about 12v. Engine on-should be 14-15v. You can check this on the battery.
2. Temp-check the radiator fluid at the cap when the engine is warm. A basting thermometer will work, but be careful if you remove the cap when the engine is hot. Some fluid will probably blow out. Depending on the thermostat, it should read between 160-200 degrees.
3. Oil pressure will require the use of a seperate guage plumbed into the pressures system.
There are more sophisticated ways of checking these things, but these are easy and quick. If the guages all read ok, I wouldn't get too concerned. At least you know the gas guage works!
1. Alternator-check voltage engine off-should be about 12v. Engine on-should be 14-15v. You can check this on the battery.
2. Temp-check the radiator fluid at the cap when the engine is warm. A basting thermometer will work, but be careful if you remove the cap when the engine is hot. Some fluid will probably blow out. Depending on the thermostat, it should read between 160-200 degrees.
3. Oil pressure will require the use of a seperate guage plumbed into the pressures system.
There are more sophisticated ways of checking these things, but these are easy and quick. If the guages all read ok, I wouldn't get too concerned. At least you know the gas guage works!
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Elder User
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From: Seattle
Gauges
That doesn't sound too good.
So basically the gauges are just big idiot lights? Not unexpected, I guess if you want accuracy then you should be buying real gauges, and not relying on what's provided to give some visual comfort.
Doesn't sound like its too easy to test the gauge either. The battery one isn't tough, but it begs the question of just what exactly is that gauge reading? Is it the voltage drain on the alternator, the battery drain, the system voltage?
They're nice to see, but if they don't really work all that well then I almost wish they wouldn't provide them. Another thing about that is that they wouldn't be all that hard to get working nice and accurate. If Ford can do pretty good exhaust gas analysis then they should be able to provide a nice stock set of gauges. It almost sounds like the gauges are there simply because people expect to see them - even if they don't do much.
The whole reason I brought this up was from an incident back when I was trying to figure out why my Audi was chewing up batteries. The alternator was shot but the gauge wasn't showing a problem. If there had been a nice easy way to troubleshoot the gauge I wouldn't have spent money on new batteries.
So basically the gauges are just big idiot lights? Not unexpected, I guess if you want accuracy then you should be buying real gauges, and not relying on what's provided to give some visual comfort.
Doesn't sound like its too easy to test the gauge either. The battery one isn't tough, but it begs the question of just what exactly is that gauge reading? Is it the voltage drain on the alternator, the battery drain, the system voltage?
They're nice to see, but if they don't really work all that well then I almost wish they wouldn't provide them. Another thing about that is that they wouldn't be all that hard to get working nice and accurate. If Ford can do pretty good exhaust gas analysis then they should be able to provide a nice stock set of gauges. It almost sounds like the gauges are there simply because people expect to see them - even if they don't do much.
The whole reason I brought this up was from an incident back when I was trying to figure out why my Audi was chewing up batteries. The alternator was shot but the gauge wasn't showing a problem. If there had been a nice easy way to troubleshoot the gauge I wouldn't have spent money on new batteries.
Junior User
Joined: Jan 2004
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From: Shortsville, NY
the oil pressure and temp gauges are pretty much over sized idiot lights, but the alt. gauge should move some. Try putting on a load...ie headlights on high beam and turn on your heater fan to high and watch your gauge. Ford a while back had issues with the temp sending units moving back and forth to much with the coolant temp changing. The same was for the oil sending unit but would drop off when it got closer to the next oil change, to many complaints.
Posting Guru
Joined: Nov 2003
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From: Homer, Alaska
I'm sure the guages are there for the guys. Most women have not a clue (at least my wife doesn't) about how to read a guage. That's why they put the "check guage" light on these things. Ford is covering all the bases. I like guages. My wife hasn't a clue. It would be nice to know that the oil pressure really is good, but I don't count on the guage. On the plus side, usually if there is a problem, it will be obvious. The guages won't help much. Something will fail, and you will fix it. Hopefully, it won't be a rod through the oil pan.
