Digital temperature gauge correlation to actual temps

June 08, 2024, 09:21:55 PM

So, anyone who has driven one of these cars with a full digital gauge cluster is aware that the normal operation of the temperature gauge shows 4 bars illuminated when at operating temperature.

My 87, which is heavily modified, had an inoperative gauge for years. Fast forward to me properly wiring it up and getting the correct sender for it. The gauge itself in this particular car will not show above 3 bars and it takes FOREVER to even read that. I have not hooked up any mechanical gauge to the vehicle yet but suffice to say, it definitely gets hot when you get on her. Big 3 core radiator, 180 degree thermostat and a high volume water pump are in the car and have been for a while but the gauge was inoperative before all that went in.

Anyway, my question is this.

What temperatures or temperature ranges do each bar on the digital temperature gauge represent provided the gauge, wiring, and sender are all working properly? I can't find anything in the shop manuals for it. My gauges all self test good as per the tests in the shop manual.

I've had an issue with the oil chime going off at approximately 20psi for YEARS (it persisted even after a full gauge cluster swap and a few different sending units) and wonder if I have an issue with the ribbon behind the cluster itself that may cause both of these gauges to read incorrectly.

Obviously I have to hook up some mechanical gauge to verify an actual temperature at this point but would LOVE know the temperature ranges for the actual digital gauge.

If anyone has this info, please share it.

Thanks in advance!

Re: Digital temperature gauge correlation to actual temps

Reply #1 – June 09, 2024, 09:34:41 AM

Paul, the bars are not representational of any value or increment. They are just there to show a general reading of the gauge, nothing specific. For all its 1980s aspirations, the full digital gauges are pretty much nothing more than abstract guesswork rather than actual, true displays of what's really going on. It's no wonder people sometimes hook up auxiliary gauges just to get a clearer picture of the temp and oil and volts situations.

Very rarely, grounding out the gauge can "reset" it. And a temp sending unit change can also help sometimes (if you can find one for a digital gauge).

Re: Digital temperature gauge correlation to actual temps

Reply #2 – June 09, 2024, 03:39:16 PM

If these senders are resistance based you can use the gauge fix thing you splice inline i mentioned in my fuel sender thread(Tanks MeterMatch but there are others) to make the gauge read at any level you want, provided you know the values for each bar in relation to the temp so you dont blow your headgasket.
Have you ever checked the engine ground strap?