Many people like having gauges rather than lights to apprise them of such things as engine temperature and oil pressure – chiefly on the premise that a gauge will let you see changes (by the numbers) prior to failures.
For example, in an older car with an oil pressure or water (coolant) temperature gauge, you can see the needle rise from zero pressure – or dead cold – to normal pressure (say 60 psi) and temperature (say 190 degrees). More importantly, you can see – assuming you’re looking – the oil pressure needle fall or waver, indicating a possible developing problem with the oiling system or the temperature needle rising, indicating possible imminent overheating. The key thing being seeing these warnings in time to prevent serious problems, as by shutting off the engine or pulling off to the shoulder to let the engine cool down, etc.
Warning lights – also known derisively as idiot lights – are designed to come on when it’s too late. If the “oil” light comes on, it means you have already lost oil pressure. If the “temp” light comes on, the engine is already overheating. It is like the pilot of an airplane you’re flying in telling you the plane is about to crash. It gives you time to get right with Jesus. A gauge can give you enough time to avoid a catastrophe.
But gauges are not what they used to be. Very much of a piece with the fact that power windows and locks are not what they used to be – and for the same basic reason.
You may already know about power windows and locks in new and late-model cars. They are no longer the simple systems they once were, consisting of wires connected to a switch that – when activated – energized an electric motor (in the case of power windows) or an actuator (in the case of power locks) and the window opened or closed, etc. In new and late-model cars, the opening and closing of the windows is controlled via a computer and body control modules. Signals are sent via the switch to the computer/modules that cause the window to open or close and the doors to lock/unlock.
It only appears to be the way it used to be. Just the same as it looks like there’s a gear selector handle on the center console. What’s actually there is a kind of artifact of what was, to create an illusion of what was. Meaning, you think you are putting the transmission in Drive or Park or Reverse by moving the gear selector handle from one position to another. But all you’re doing is sending a signal to the computer that puts the transmission into Drive or Park or Reverse. There is no physical connection between your right hand and the transmission. More finely, that gear selector handle isn’t in any mechanical way connected to the transmission.
It’s a similar situation now as regards those gauges. They are no longer directly connected to the system they monitor. Instead, they have become simulations of what they used to monitor. What you’re seeing is what the computer says as regards such things as oil pressure and temperature. And the computer wants you to see what appears to be normal values. Not variations in those values, as in the past – when what you were seeing was not always uniform.
For instance, as a car aged, you might begin to notice the oil pressure readout was a little less than it was the car was new, which is to be expected as an engine wears. Same thing, basically, as regards engine temperature. As the miles and years accrue, the radiator may not cool as efficiently, causing the engine to run progressively hotter. You could see this reflected by the temp gauge.
What you see today is “normal” – until it isn’t.
By which time, of course, it is already too late.
It is also much harder to figure out what might be wrong – with the gauge. In the past, it would be either the gauge, itself or the sending unit it connected to. Or the wires connecting the one to the other. But the gauges in new and late-model cars are part of the electronic-computer-controlled matrix.
They are part of a display rather than individual components that can be removed and replaced without replacing the entire display. And good luck figuring out what they are connected to, because you can’t see or trace the connection. It is a matter of data sent – and received – and then displayed, according to the parameters of the computer that is a kind of all-controlling, all-knowing Oz who lives behind a curtain you can’t look behind.
We might just be better off going back to idiot lights.
They were at least more honest than “gauges” that give you the illusion you’re keeping track of what’s going on under the hood of your vehicle.
. . .
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Just another reason to keep my old vehicles running perpetually
Where idiocy is seemingly a virtue – BMW. “Don’t Believe Those Gauges”,
then check the oil dipstick. Oh, open the hood and BMW, in effect
says – “we don’t need no stinken’ dipstick” – our customers
wouldn’t know what it’s for. Blow the engine… no problem, for us.
Much information from checking oil with dipstick, BMW, and
others, deny an important “tool” in their newer vehicles.
The part about the windows reminded me of the old Mercedes W123. Base models were fine but the higher end 300 models apparently had a crazy vacuum system that ran everything so if the line for your door lock sprung a leak it stopped working but also your transmission would not shift or your engine wouldn’t shut off! An early prototype to total interconnectedness!
When the narrow nylon tubing split from the sending unit to the oil gauge on my little tractor, oil was spraying 10 feet out for 500 feet until I drove it to the garage apron and stopped the motor.
Bought a new oil gauge with new nylon tubing.
No more maff challenge?
Disbelieve This Survey At Your Peril
Conference Board consumer confidence dropped to its level of mid-2020, during the covid scare. It’s the blue line in this chart:
https://cms.zerohedge.com/s3/files/inline-images/bfm4E03_0.jpg?itok=y9gd0X9J
Peeps don’t make big discretionary purchases, such as houses and cars, when they are feeling insecure about the economy.
Auto makers are headed for a bad bruising. Tariffs will make it worse. It’s the end of the car biz as we know it … and I feel fine.
“What you’re seeing is what the computer says as regards such things as oil pressure and temperature. And the computer wants you to see what appears to be normal values. Not variations in those values, as in the past – when what you were seeing was not always uniform.”
This eliminates those pesky warranty inspections requested by those bothersome customers.
This goes both ways. People have become mechanical idiots over time, and don’t realize it’s normal for a temp gauge to read lower on a cold day or hotter on a warm day, or that the engine will run hotter in bumper to bumper traffic than on the highway, so they keep going into the dealer over minor BS.
Thankfully, the OBD-II interface still gives you real values for all those things the idiot gauges monitor. Some of them aren’t even connected to a sensor. The oil temperature gauge in my Focus RS was computed from the coolant temperature and how much you use the throttle. Why even bother?
‘The oil temperature gauge in my Focus RS was computed from the coolant temperature and how much you use the throttle.’ — OppositeLock
LOL. That’s like estimating your blood pressure from your age, body mass index and the paces per minute recorded by your phone. Not exactly clinical quality data.
What is particularly egregious is gages that lie to you. Chrysler is notorious for this, I caught it on my 2001 RAM Cummins and my 2014 RAM Ecodiesel. The temp says it’s 100 even when it’s sitting outside in -20 weather, and the oil pressure is designed to show a higher pressure than what it actually is. But it’s worse than that because it adjusts what you see to reflect what an experienced driver expects to see. On the Cummins it showed good pressure, even when warm but a mechanical gage showed annoyingly low pressure at hot idle. I am driven to assume someone decided there would be warranty claims for low oil pressure and ordered the condition to be covered up.
The temp says it’s 100 even when it’s sitting outside in -20 weather.
Outside air temp gauges are notoriously inaccurate at start up. Many vehicles of this vintage need to see vehicle speed for a period of time before the temp will update.
No matter where the temp sensor is placed it will be inaccurate due to solar load, residual engine heat, or thermal heat sink capacity of whatever it’s mounted to.
What reading would you like displayed right at key on?
Engine temp should display pretty close to OAT at cold start. I expect the truth, though data averaging is fine.
What is a cold start as defined by you? One hour? Overnight?
What if your overnight cold start is at high noon in Miami, in July, and your black car has been sitting in the sun all morning?
When you key on and the sensor raw data says 150F is that what you want displayed?
Overnight or more than 3 hours. And yes, that is exactly what I expect.
Although that might make you happy, that still isn’t going to make customers happy when ambient is maybe 90F-100F and the Outside Air Temp is reporting 150.
I had a Mazda Tribute (really a Ford Escape) and it would periodically lie about how much fuel I had in the tank. I had to keep tabs on how much and how long ago I put fuel in to keep myself from getting stranded. Funny thing is, I sold it to a guy for $700 after one of the rear shock mounts busted through the frame. A few months later I got a certified letter from a local towing company requesting $1100 or so to get the car out of their pound–the guy never changed the title, so they though I still owned it. What a racket. I’m guessing he might not have remembered when I warned him about the fuel gauge although it might have been something else that caused him to be left stranded. Also, I got a bill from the Illinois Tollway (thankfully only 25 cents) because I was foolish enough to not take off the license plate when I sold it. I did inform the DMV that I sold it however in case he got into an accident. From time to time, I still get letters from a company called “Endurance” about a vehicle warranty which I have no idea what it’s about, unless it is about the Tribute they might think I still own. I don’t know.
“For example, in an older car with an oil pressure or water (coolant) temperature gauge, you can see the needle rise from zero pressure – or dead cold – to normal pressure (say 60 psi) and temperature (say 190 degrees).”
And there is the problem with numbers on gauges.
Normal operating temperature is often well above 190F via pressurized cooling systems.
“Normal” oil pressure is well below 60 psi at idle when hot but can be even higher on a cold start in winter.
Let’s face it people’s knowledge of how the world of mechanical things work is abysmal and gauges just confuse them.
Average people, please. There is still a third of us out here who live in reality. And an awful lot of what we’ve lost has come from helpfully engineering out the need for competent users of technology.
I was taught that a well designed gage cluster should point in the same direction when everything was normal, making a subconscious scan easy and making an abnormal condition jump out. Exceptions being fuel, and (somewhat) speedometer. The numbers are important but secondary.
“Average people, please. There is still a third of us out here who live in reality. And an awful lot of what we’ve lost has come from helpfully engineering out the need for competent users of technology.”
Taking what you say at face value. Even if the third know how to read and interpret the gauges properly, the warranty claims and costs created by the other 2/3’s will be excessive and lead to loss of numbers and to the addition of lots of damping to ensure gauges don’t move around too much.
‘Let’s face it people’s knowledge of how the world of mechanical things work is abysmal and gauges just confuse them.’ — Burn it Down
When I use a digital multimeter, I just want an accurate reading … whether it’s good, bad, normal, abnormal, expected, or confusing.
I don’t need no algorithm intermediating. Just the data, please.
“I don’t need no algorithm intermediating. Just the data, please.”
You are the exception.
I’ve spent hundreds upon hundreds, probably thousands of hours over the course of my career reviewing warranty data and customer comments about gauges.
One product I worked on didn’t have enough damping on the coolant temperature gauge. If you watched it closely enough, you could tell when the thermostat was cycling open & closed.
The coolant gauge wavered ever so slightly.
Your head would explode if you knew the warranty costs and the cost of the software changes required to “fix” it.
Seriously? A simple averaging algorithm would entirely take care of that. It would take minutes to write, and a few days to validate and fine tune.
Though corporations are incredible at creating useless work and expense. I’ve always been an outside contractor/scapegoat. Those have to produce real results on a tight budget so the insiders can take credit and play political games.
I’m not trying to be mean here but your comment of how easy it is only shows that you have no understanding of the what it takes to implement changes within an industry that is so heavily regulated by FMVSS and has massive recall risk if a simple software averaging algorithm inadvertently screws up something else.
The worst part of working in the industry was watching how often software screw ups happen and how much money they cost.
And I’m not trying to be personal, or minimize the suck of dealing with communist lawyers. But presenting honest data to the customer rather than showing him what you want him to see is dishonest and unethical.
And I have been programming complex systems for over 35 years, it’s as simple as implementing a clock, recording the data on the time hack, and presenting the mean over 10, or 100, or however many samples it takes to make a reliable reading within the limitations of the system. If I, in industry, show the customer that his process temperature is 320 degrees because that’s what he wants, when in fact its 280, and it makes defective product, then I am going to have to fix it, and he can and will demand redress.
And by the way, I do agree on software screw ups being way too common and costing way more than most can imagine.
Case in point, lots of major errors in that post. Were it software I’d have spotted it and fixed it immediately… means culpa.
I get your point but your assuming there is:
Ability to draw power to do continuous real time data acquisition and processing. Ignition Off Draw (IOD) is micromanaged to the millivolt level to avoid draining batteries over extended travel stays. I’m pretty sure you expect the vehicle to start after being parked 3-4 weeks at an airport? There is no excess power to be keeping an instrument cluster module awake 24/7 to do processing of ambient temperature.
RAM Memory is available somewhere to save and do that processing. Don’t tell me it should be done in the engine ECU because that is an emissions component. The last place in the world I want the OAT convenience display being stored and data processed is in an emissions component.
Also by the way there will likely be more than 1 supplier of the hardware for your to validate against anytime you make a change.
The point being, you are not looking at all the complexity involved and over simplifying what it takes to accomplish what you perceive as a simple task.
Don’t get me wrong I don’t like the inaccuracy either.
Modern cars do a much better job of minimizing that inaccuracy due to more on-board memory and processing power but to expect that out of a 90s or early 2000’s era vehicle was not feasible in that era.
1. We are talking about engine coolant temperature and engine oil pressure. OAT is not important. It’s only relevant as far as it affects engine coolant and oil viscosity.
2. The oil pressure and temp should start sampling as soon as the key goes to on. And they do.
‘If you watched it closely enough, you could tell when the thermostat was cycling open & closed.’ — Burn it Down
I would LOVE that. It’s like trying to spot my electric water heater cycling on and off in the utility’s hourly meter sampling. I’ve never succeeded because the sampling data is too sparse.
Again – you’re a weirdo Jim – Lol!
The reality is you had customers bringing vehicles in for warranty claims . . . No trouble found. Dealer has to be paid for that diagnostic time.
In the worst case, I’m aware of one CA lemon law buyback of the vehicle because the gauge couldn’t be fixed after four or more repair attempts. Was likely just buyer remorse but they were able to use the inability to repair instruments as a means to force a lemon law buyback.
I agree. That way I know both the thermostat and the gage are working.
Though that may be what you want – I assure you that isn’t what most customers wanted and the insane costs of the warranty charge off proved that. There is a level of warranty and customer dissatisfaction that an OEM accepts as not being able to please everyone all the time.
Customers do not want to see the coolant temp needle wavering around in response to the thermostat.
When the customer satisfaction data and warranty costs become excessive they cannot be ignored and the cost to implement the change is cost neutral or pays for itself.
One of the toughest aspects of working in the industry was learning that what we as enthusiasts might like, isn’t always what customers value.
Thanks. I had no idea I was looking at such extensively massaged data.
Next thing you know, an onboard AI assistant will tell you whether your car is feeling okay today. No need for gauges. Trust the AI.
Or get a good quality OBD II Bluetooth connector and some good quality software on your phone and set your phone to read the actual data that your computer sees and display that as your gauges…
Actually fake gauges are nothing new. On my 1996 Mustang, the oil pressure always jumped to about 3/4. When I spoke with an engineer, they said that if the oil pressure was in teh normal “range” thats where it sat. If it failed, it would read 0.
That can be fixed. Ford has had two types of oil pressure sending units forever. One runs a gauge, one is merely a switch that sends a “normal” reading when the oil pressure is in the “normal” range. The gauge will work with either unit while an idiot light only works with the switch type unit. Replace the sending sensor with an actual gauge type and your gauge will act as a gauge and not a dummy gauge.
Same with Toyota. I had a 1989 pickup that had a fairly wide dead zone in the temp gauge around normal. The sender is real and the needle isn’t just on-off but what it looks like to me is the circuit is designed to have the needle in effect have almost no movement for about +/- 20 degrees around 195F. I notice it when I put in a slightly lower temp thermostat and the need would move up and down as you’d expect as you increase and decrease load. As I thought about it the only time I remember the needle really going above normal was towing a U-Haul that was too much for that little 4 cylinder and it did actually boil over.
The explanation for this is in the olden days people understood more or less that temp and oil pressure would go up and down and that the normal location was really only true under medium load at highway speed. Stopped at a light the oil pressure would droop, pulling a long hill the temp should rise. You need to watch that it doesn’t go too far and that takes experience and knowledge. So manufacturers designed needles to give you the impression of information but the dead zones around normal values are to reduce stupid questions and complaints. I ended up modifying my cluster to linearize the temp needle.
Modern cars with gauges are just expanding on how speedometers have worked for a long time. In the mid 1990s most cars lost their speedometer cable for a vehicle speed sender. This was two-fold decision, the ECU needs to know vehicle speed anyway and those cables are notorious for wearing and breaking. So solves multiple problem and no more bouncy needles. The needle is driven proportional to a stream of pulses from that sensor (or an output of the ECU) instead of directly by the RPM of a cable. Now all the gauges are just analog representations of the data collected by the ECU. Those OBD dongles you pair with a phone app are showing the same data and you can get the accurate value that way, too. They tried to ditch needles for number displays back in the day but as any pilot will tell you having dials and needles is quicker and more intuitive interface for us.
Geez Eric, it seems that every time I read something here on automobiles made within the past 10 years or so, it makes me more determined NOT to buy one, and to try to keep my late 1990s truck running as long as possible. But for whatever reason, some people out there still get a kick out of buying a brand new vehicle despite all the computerized geezmos & Nanny State stuff they’re equipped with, even if they’re leasing it and have to make monthly payments on it.
Me too, John –
I’m on the front line, so to speak – because I get access to the newest stuff before most people, so I get to see firsthand what everyone else is going to see soon. And it doesn’t look good.
I used to take my old truck for granted. Now I treasure it.
Eric,
I treasure my old truck as well after having read so much about newer vehicles on your site. I also don’t have to make monthly payments on it as I bought it used over 10 years ago. Not only that, I don’t know if you feel the same way, but in my opinion many automobiles from pre-2010, particularly from the 20th century, also look waaaaaaaaaaay better than automobiles made now. I see many restored older vehicles for sale on the internet, and I think they’re beautiful compared to brand new automobiles. Many vehicles made now are just flat out ugly, like Tesla’s Cybertruck or the Ford Mustang Mach-E, or they look like something out of a dystopian movie.
‘What you see today is “normal” – until it isn’t.’ — eric
Seems like two different subjects are under discussion here. One is gauges that lack numbers, such as the photo of a temperature gauge labeled C, N and H. The engine control computer receives a definite digital value (e.g. 182 degrees F). So why isn’t the gauge labeled accordingly?
Apparently, interface designers assume that hard values will confuse and perplex the innumerate. So they ‘helpfully’ translate values into a vague, quantitative C-N-H.
It’s of a piece with my email platform, which ‘helpfully’ labels emails from 24 hours ago as ‘Yesterday’ rather than ‘March 24, 2025’. This is exasperating, since I just want the damned date on every email in a consistent, unvarying, numerical format.
A second subject is whether computer-fed gauges are as accurate as old-school gauges with sending units. I know of no reason to think they aren’t. It’s the dumbed-down interface that offends.
Well everything is fake now so it’s not surprising the gauges in your car are fake now.
The Torque app on google play, and a $20 OBDII bluetooth dongle is an easy way to add gauges to a vehicle, based solely off what the computer sees, easier than driving around with a scan tool if you don’t trust “what the computer wants you to see”.
Oh mang, BaDnOn. I think Eric just said to use the BFH. It’s your only hope.
BFH is the answer
Busty Female Human? By all means use one if you’ve got one!
Yes lawd!
Haha and no math exam.
Hi Ugg,
We’re dialing back the math exams. Regulars/registered users should now be able to post comments without taking a math exam. The math exam is only required for new people who’ve not posted before – to weed out the spammers… we hope!