okfoz

Back-story:
Today I had the opportunity to speak to the Engineer of Ford who designed the gauge clusters for Ford from the 80's thru 2007. (I know it is not GM)

Have you ever noticed how new cars when the temperature gauge finally warms up and gets to the middle and will stick there like glue, just below the center line, and how the Oil Pressure gauge goes to just past center and sticks like glue to that spot, the oil pressure might wiggle a little but not much?

The reason why is this: the Oil pressure gauge might not really be a gauge at all on newer cars. Older cars the gauge was connected directly to a sensor, it would send a reading from the sensor to the gauge and give you a reading. This would cause the gauge to bob up and down with RPM and give you a reading... What they found was people freaked out if the gauge would go low, which was not a real problem but just a psychological problem, so in order to lower service calls on the problem they started making it a switch, when the car was turned on (and running), instead of having a low pressure light it would go to a the middle and stick there... Toyota got the idea to tie it to the tachometer which would allow it to bobble a little and give you the feeling that it was actually reading pressure... This saved $2.00 per vehicle and saved more in unnecessary service calls.

The second gauge that is the Temperature gauge. Where our cars would go and read the temp from a sensor on a smooth curve, the new cars with the computer will stay in the middle from 180°F to 230°F At which point then it will go up... This also decreased service calls because once again people would freak out when they watched the needle go above that center line.

In the end new cars they have the Oil pressure gauge set to be just above or right on the center line, and the temp gauge to be on or just below the center line...

Even the recent Ford GT had an idiot oil pressure gauge...

Why do I bring this up? When I drive my cars the temp will fluctuate all over the place, or the oil pressure will drop, I always was slightly concerned but never got too bent out of shape. I have taken my car to have the Radiator people take a look at it and they always said it was fine... I guess I should just trust the little red and orange lines more...

And I thought I would share...

Firechicken86

iTrader: (1)

This actually makes a lot of sense. For my winter dd I've been driving around a pt cruiser (gross, I know) until I get my bird on the road. I was driving for a good hour in it the other day with the temperature gauge stuck on the middle when all of a sudden it instantly shot right into the red and I could hear boiling, turns out it was very low on coolant. Like you said, it seemed like it was controlled by a switch as the needle didn't gradually rise with the temperature. That's why I thought it was weird when I took my bird out on a little test spin not too long ago when I saw my oil pressure gauge being a lot more active than more modern cars I've driven. Thanks for sharing!

Reid Fleming

iTrader: (2)

You should have asked him why Ford gauges had no indication of actual markings. Their coolant gauges used to read C\_______/H and the needle would be somewhere in between. Same thing with oil pressure L\_______/H

A different point altogether. I much prefer volt gauges were 13 volts is the middle setting, rather than 14 volts. Because on a 14 volt gauge, most of the time your needle is going to be reading below that marking. So it always "seems" like you're running low voltage. But if it's reading above a 13 volt marking, then it "seems" like you're doing fine.

Our 2002 Blazer does a strange thing with the coolant gauge. When you shut it off, everything goes down to their minimal setting on the pegs. But about 10 seconds later, the coolant temp needle will start moving back up to the middle setting (210°). It has nothing to do with temperature because it will do it if you shut it off after driving 5 feet on a cold start. I'm guessing there is a powered sensor that is getting shut off and drifting back to a neutral middle position.

Reid Fleming

iTrader: (2)

I quite like that the oil pressure is active. I use it to judge when the engine is warmed up. Because it will move down about 1 tiny notch on the gauge while driving at near highway speeds when the car is warmed up. And you get a good 1/4 of the gauge movement when coming to a stop light when it's warmed up, rather than just sitting on the max line.

Jason E

The 2000 model year is when GM changed the sending units in the F bodies to work similarly to what you're saying...and it does make a difference in what you see. My 97 and 00 have the same appearance to their gage clusters...but the oil pressure and temp gages on the 97 move far more than the 00.

okfoz

Your gauges, I believe are actually stepper motors, it might be somehow getting a stray signal from somewhere causing it to go haywire. I have a 2005 Buick Rainier (same thing as a trailblazer/Envoy, but labeled Buick) and my temp Gauge does not go to rest either, the fuel gauge can be all over the map... You can replace the stepper motors pretty easily if you want, I got a set of 6 Motors from e-bay and fixed about half of them a few years back, looks like I have to do the other half now.

My point was to writing this is really when I drive my "newer" car the needles hardly move, in comparison to my older cars... This is actually pretty nice, in one respect because if you trust your gauges they are telling you that everything is all right, the oil pressure gauge is actually an idiot light. But when you are driving, not having to worry about things like overheating and low oil pressure, as long as it is all within acceptable parameters. But at the same time, unlike thirdgens where the gauges are actually gauges, not a computer simulation of what they think you should be seeing, knowing that they are actually real readings, vs fake readings like on the new cars... I have gotten used to the fake gauges in some respect, because I expect my thirdgen to work the same way, when in fact my thirdgens will never have perfect readings like the newer cars, ever...

scottmoyer

On the newer cars, it's easy to verify the gauge readings by using an OBD2 reader and your smartphone. I bought an OBD2 reader from eBay for about $15 and downloaded an app called Torque. You can install many different gauges and compare them to the dash. I noticed that my trucks speedo is all localized in the dash, but the ECM outputs the speed to my phone. I was also able to look at trans temp, etc when the truck doesn't have that gauge.

okfoz

$15?!? That would be killer, which one did you get?

Too bad they do not have an OBD 1 one for our cars, that would be better yet.

John

scottmoyer

Do an eBay search for "bluetooth OBD2". They are usually called ELM327 or something like that. Then look up the Torque app and see what options you can monitor. You can pull codes, clear codes and monitor all sorts of ECM activity.

okfoz

Apparently it does not work with the iPhone, iPod or any other Apple crap... Android or Windows phone is looking more appetizing

John

scottmoyer

BTW John, I traded my son this past weekend a new iPhone 5 for his Samsung Galaxy S3. I was really beginning to not like the iPhone due to it's limitations. One of them was not being able to use the Torque app.

JT

iTrader: (1)

Our OBD 1 vehicles don't have near the amount of information available as the OBD 2 vehicles and so even if there was a device that supports them we wouldn't see as much data. Today's cars have so much sensors and actuators going through computers to make seeing that data, or even activating it, possible. In Reid Fleming's Blazer, simple things like power door locks and interior lamp control go through a body computer before the end actuator. In the case of the interior lamps, it allows disabling them to prevent a drained battery if left on mistakenly or door left open too long. That information can usually be seen at the computer for troubleshooting circuits.

On our cars, I use TunerPro with a laptop to read the values from the ECM (engine temperature, IAC counts, timing, error codes, etc.).

Jim85IROC

iTrader: (2)

I read an article years ago about GM's fuel gauges, and in particular, the one in the early 80s Cadillacs with the digital dash. Initially GM was getting a lot of complaints of poor fuel economy, essentially because the gauge was too accurate. As soon as you drove away from the gas station, the first bar would go out (after all, it's not 100% full anymore). They fixed the fuel economy complaints by reprogramming the gauge to keep the top bar illuminated longer. Unfortunately, this is a trend that GM maintained since then. My GTA can go close to 100 miles before the first bar goes out on the gas gauge, and then it starts to torpedo. My Corvette was the same way. It's irritating.

blacksunshine'91

iTrader: (10)

I have the same issue with my analog gauges. When I fill up from empty, it only takes 10 gallons to go from E to F. Yet I still have another 5 gallons above the F so it takes a while to get the needle to start moving but once it does it doesn't take long to reach E.

TTOP350

iTrader: (8)

That also has a bit to do with the shape of the tanks.
Looks like a shoebox with a triangle stuck to the bottom. Helps with rearend/suspension clearance and fuel pickup a bit also.

okfoz

My fuel gauge does the same thing on my 3rd gens... stays at Full till about half tank, then it drops... My newer cars seem to be a bit more controlled, it will stay on Full for a little while, Half a tank is about 45% full but when the light comes on find a station within 20 miles or you are stranded.