Since our cars don't have a coolant gauge, is there an aftermarket device that'll display this information?

thanks in advance

 

The ECM has a coolant temperature sensor - its reading can be retrieved and displayed with a scan tool (plugs into the diagnostic port near the steering column). There are remarkably cheap aftermarket dash-mount gauge-displays that use the same trick to get their information. There are also bluetooth diagnostic dongles that (with an app) turn your smart phone into a scan tool. I'm sure there are gauge apps as well.

So, yes there are such displays. Hopefully folks will chime in with what works for them.

 

In the European sister forum clubjazz.org several members use and recommend Scangauge 2 for monitoring coolant temperature todethrr with various other interesting parametrers. I have been considering it too, just haven't got it done yet.

Then there is another option for those who like to work with hardware. Find a suitable location on the engine to drill and tap a hole for an additional sensor and use a conventional voltage-based aftermarket gauge. This is then totally independent of the engine management and original vehicle information systems.

 

I use an UltraGauge to display coolant temp, 12v battery voltage, catalytic converter temperature (because why not), and a bunch of other outputs from the ECM. I think they have a newer bluetooth version so you don't have to have the dangly cord that I deal with.

https://ultra-gauge.com/ultragauge/index.htm

I bought the UltraGauge for my previous car (Toyota Yaris hatchback) which lacked not only a coolant gauge but also a tachometer.

I much prefer seeing the coolant temperature and 12v battery information to relying on dummy lights. One of my few complaints about the GE8 is wasting 1/3 of the gauge cluster on a giant fuel gauge when that space could have easily contained several smaller gauges (including fuel) of critical importance.

 

Yes, I have one of them. I sometimes use it with an old GPS.

By the way, those installed temp gauges don't display the actual temperature. People got upset when they saw the needle rise, so manufacturers made the needle stay in the middle unless the temp rose too high. I've had cars with mechanical temperature gauges. They were good.

 

Wow, thanks for the replies!
You guys give me a lot to consider

 

Much cheaper than the ultragauge and better looking too, many people in the Fit community use this

 

I had an OBD heads up display to show temps. I also chose it to show speed in MPG and speed in MPH (I live in Canada!).

 

Which one did you have?

 

OBD2 HUD

I still have it, but don't need it. Extremely reliable. Went through cold winters and hot summers. No issues.

 

Yeah, $84 is too much, but $38 is a possibility. Does it glue to the dash. That's a drawback.

 

One semi-interesting difference between those reflects-off-the-glass (proper HUD) segmented panels and the upright gauge displays is the display tech. The HUD uses permanent segments (printed or silk-screened plastic film with clear, colored or black areas) with an LED or two behind each segment to illuminate it or leave it dark.
The $38 upright gauge thing is using a generic rectangular color LCD display in a stylized housing. LCDs also use LEDs to produce light, but its one big always-on LED panel behind the whole display, called a backlight. The LCD pane (it uses layers of glass for structural support) sits in front of the backlight and blocks or allows that light through to create light or dark areas of an image. LCDs can also be made with permanent segments, but almost all modern LCDs (including the upright-gauge-product) are made with a grid of tiny squares or rectangles - pixels. Pixel displays let the user (or at least the system programmer) change the display layout to their liking, and display stuff like video feeds.
There's several relevant downsides to LCD tech (compared to LED segments) in automotive applications:
The biggest (in my opinion) is something you may have heard about televisions: LCDs can't display perfect black. This will be relevant at night, when the dark portions of the "gauge" face will still glow grey. Your eyes adapt to the overall light level of the scene, so lots of LCDs on the dash (even if they're displaying black) will negatively impact your ability to see down the road. Hopefully the gauge product turns down the backlight intensity at night.
Next, the optical wizardry in the LCD pane soaks up a significant amount of light. This causes daylight-readability issues unless a very powerful backlight is used (which leads back to the perfect-black issue). The LCD gauge-style product needs a hood over it to reduce glare, while the LED HUD-style display is so bright that its reflection off the windshield while pointed at the sky is still perfectly visible. Though admittedly, daylight will light up the segments of the LED display to some degree.
Some LCDs can't handle temperature extremes. They stop functioning until they warm up or cool down. LED displays tend to be more rugged, though they can change color while submerged in a liquid nitrogen bath.

 

+2

I use the Scangauge III. It's not cheap, but it's useful and reliable and the lighting matches the illumination in my 2012 Fit.

 

You are right, the style fits. However, I prefer Sg 2, because it's smaller and thus easier to mount unnoticeable. I've been thinking under the ventilation controls.

 

No. All of my HUD's came with a small rectangular sticky pad, but the GK dashboard is unusually smooth and slippery.
I use "dumb dumb putty" or butyl (the same stuff used in sound deadening tiles.

 

Multiple different mounts come with it, I used the suction cup mount to the small window on the side of the dash

 

Is there an LED model you'd recommend?

 

I haven't used one in the past ~10 years (and that one doesn't do coolant temperature), so no. Just make sure it has the info you're interested in already on the display markings, because they don't change. For instance, the unit Action Jackson linked to has a temperature bar graph in what appears to be units of 10?C. That's less precise than digits, but probably enough for most people's purposes (and much more precise than the stock cold/normal/overheating indications).
HUD displays will have a slight double-image when bounced off the windshield glass, as the image bounces off the inside surface of the glass, and again off the outside surface. There's semi-mirrored "polarizer" film (that name also describes a part of LCD panels, so make sure it's a HUD product) that can be applied to the inside of the glass to get a clean image if that bothers you.

 

It actually displays precise temperature.

Let me attempt to test to be sure.

 

I used that new multi-sensor device on a short drive yesterday, and I see one big drawback: it's going be hard for me to keep my eyes on the road. 😁

It presents so much information in so many different ways.

I'm going to try to attach a GPS mount to it so it can snap into that mount. Right now, I'm using Velcro because I don't want to use the double-sided tape.