Take a reading directly off the sensor with a multimeter and compare it to the gauge reading. You may have a wiring problem if the sensor isn’t bad

Barry You are spot on. I remember in a electrical class years ago. The Ford instructor said out of every three electrical parts one will be bad new out of the box. I was a new Ford mechanic at the time and was dumb founded

Like previously mentioned 800 ohm's doesn't sound off when engine is cold. Measuring at the hose isn't going to show hot until the thermostat is opened (approximately 180-195 degrees F). You could put a 500,75,19 ohm resistor from the sensor wire to ground and see what the gauge reads, that would check wiring back to the gauge.

My Dakota digital runs cool during the fall, winter and spring. During the summer it runs hot. I tested hosed like you have. I look forward to your next video on this. I did think of adding a mechanical temp sensor just to get a true reading.

Oh man I was thinking about getting a set of dakotas for my 68 stang but after seeing your isses, maybe not. Love the videos on the 68, watch some to figure some issues I was having, they helped alot thx.

I agree with Nick, use a multimeter on the ohm setting to measure the resistance of the sensor. You may find a couple of things, 1: bad sensor (which I doubt) 2: the sensor is a miss match for the Dakota instrumentation 3: As Nick suggest maybe a wiring problem. Good Luck!

Barry, on my 70 with the stock gauges I was having issues getting the gauges to work as well. I ended up taking the instrument cluster out and added 2 grounds on either side from where it's screwed in place to secure it in place. That helped to get the volt, gas & oil gauges working but still having issues with the temp sender. I noticed if you tap (with effort) the temp gauge startes to function but still goes out. So I'm guessing its the actual gauge itself. It still could be the wiring itself, as I have the factory harness in it. I also added a set of aftermarket redundant oil pressure & temperature gauges just to be safe. Keep us posted on the progress.

The original gauge works on a " pulse". You are awesome!

You can test the sender. Also test the sender grounding with multimeter between base of the sender and the cylinder head to make sure there's not a problem there. If that checks out, then as Nick and Jerry said, check for a wiring problem. Good luck, Barry.

The temp sensor is reading the temp of the intake because the sensor is installed in the bushings. Call dakota digital and tell them the problem and they will send you a longer sensor at no charge. they are a great company. when they send you the new sensor get a pipe tap and run the threads down a little farther in the intake and the bushing. use a steel bushing not a brass one. i had the same problem on my 69 camaro. this fixed it. you are wanting to get the sensor as far down into the water port as you can so it does not get heat soaked from the intake.

hi barry grate show .barry keep up the good work .

Back when I was still working , Electric senders sometimes would show excess resistance when too much teflon tape was used or the paste thread sealant was used . East test is to use a multimeter on the sender out of the engine hanging in a pot of water heater on a stove with a known good cooking thermometer and taking readings . Only takes about 15 minutes to set up and take readings . If the readings are off there.... bad sender , if they are good sender is still not grounded to the engine well enough or the wire to the gauge has too much resistance or bad connection

Make sure to check temp at the sender location on the head. There can easily be a 30 deg difference between head and hoses. X2 check you have good ground from engine to battery. Chip just a bit of paint off from where the ground strap is bolted down, firewall and block. You may also want to run a ground strap from fender to battery. All things that helped fix issues for me. Good luck.

I would say that years ago reliability may have been a concern. Nowadays I would say that is less likely. I would do an ohm check between the sensor tip and the ground body on this as well as temporary wrap a ground wire around the sensor and clamp onto the ground or negative on the battery. I would also be doing a temperature reading at the sensor being that that is where it is getting its information. Best of luck

If you used Teflon tape on your sensor, that may be insulating it from ground. Try it without the tape.

I would test the sensor the same way I'd test a thermostat. Wire up your sensor in a pot of water on the stove, hooked up with your gauge and with a thermometer, check the readings. BIM is bus interface module, I believe. I think it allows you to have another tempt reading on your gauges.

Check the sender connection to the block. If you used a lot of Teflon or pipe compound there may be a high resistance connection between the sender case and the block. Tommy

It's a 2 wire sender doesn't need a ground path through the engine. We are experiencing same problem and getting runaround from Dakota ditigal

800+ ohms might be right considering the difference between 100F and 200F is 425ohms and from 200 to 300 is only 56ohms. I seems like the resistance drop is on a logarithmic scale which is common in electronics. Definitely check with a multi-meter as other have said but I think its something else.

Thanks for sharing this. I was going to put digital gauges in my 65 20 years ago. Instead I used the GT gauges with the pony wood grain surround. Wish I went with the digital back then. Was a bit pricy though for me years ago. My suggestion to you is to try another sensor. I believe you said you had a separate sensor for your cooling fans. Can you connect the wire going to the gauge to the fan driving the fans? Would be interesting if you get a different reading. I’ve learned the hard way, just because it’s new doesn’t mean it’s good.

when you fitted earth from motor to fire wall "clean paint" as it can act as insulator, just relying on the thread for earthing just doesn't cut it . the other thing to try have you got to much sealer on the sender, not earthing to motor giving wrong resistance, keep up the great work good luck

Hey Barry. Your problem could be the connections or the wire itself. I would ohm out the wire from the sender to the cluster. Maybe there is corrosion at the firewall block connector. Another option to test would be to run a wire externally between the two to make the process simple. Always a chance the sensor is faulty too but it's a long shot. In my experience things like this are connection problems. Good luck.

If you look at the instructions for that thermal gun you’ll probably find at the distance you are testing, the area the sensor is averaging is quite large. Probably 8” in diameter. Stick that gun right on the hose and even then the gun will be reading low. As a test shoot the thermostat housing then scrape to bare metal and re-test, you’ll find it reads higher. Immersion sensor is the only way to know the true temp.

I sent Dakota Digital msg to tech dep. One of the things they said to do was run terminal screws in/out several times to clean production coating or debris from contacts. check ohms at wires at control box and at sensor, if not the same there is a problem in the wires. make sure sensor in in water, no air pockets for steam. I haven't started my testing yet, waiting until owner is back from vacation. We installed a manual gauge in, we were off by 12 to 16 degrees. hope this helps you..

Someone else referenced same issue in general, but thought I'd pass along the note from a Dakota Digital (Temp Sensor/Gauge) Installation manual: "These senders have a tapered self-sealing thread. The engine and sender threads should be cleaned before installation and no tape or sealant should be used on the threads". (Do I think that's a guaranteed fix? Not really, but when I'm trying to figure something out that is stumping me, I tend to grasp at any straw within reach....) Hope you get it fixed as the Dakota gauge pack for a 69 is on my 'Should I spend that kind of money' list. Good luck.

sensor change or a resitor inline to lower the voltage from the sensor possibly

No advise just glad it’s still beautiful and not overheating 🥵

1) 800 ohms is probably right when it's under 100f. Test the resistance at a higher temp and see what it says. 2) you have a thermostat, presumably it's a 180 or 190 deg thermostat. That means you won't have full flow through the radiator at 170 to 180 deg, and you should expect your hoses to be cooler because it's barely trickling through yet. Much better to take it for a drive let it heat soak, let the thermostat full open then compare. A 180 degree thermostat only starts to crack open at 180 and usually isn't fully open till 190. Try it in a saucepan with a meat thermometer and you'll see. 3) I have the same system as you and also and Edelbrock pro Flo 4 system which has its own coolant sensor (so two digital sensors on the engine) and they agree within a few deg f. The hoses always read cooler on an IR gun. I don't think anythings wrong with the gauge If it reads crazy hot again pull over and make sure it isn't actually overheating there may be a different problem. Next time I fire up I will check the gauge, the ohms the Edelbrock reading and hit my hose with an IR gun for comparison.

May have a slight high open(loose connection/bad splice/chewed up wire)

When you put the sensor in, did you use any ptfe tape? Generally the temp Sensors have a tapered thread, so you don’t need any ptfe tape. If so that can throw off any grounding with the block too. That might be why you’re getting the high olms. Other than that, I’d get Dakota to get you a new temp sensor.

Nothing wrong with sensor, at 74 degrees that is a reasonable resistance if you plot the log scale of resistance vs temperature. 90% of all electrical issues generally tend to be loose connections.

Had same problem with intelletronix, 30 degrees off, they sent me new sender and all was good

Test the gauge. Get a potentiometer with 500+ ohm scale. Put in place of the sender. Using multimeter, set the ohms for each temp (from the book) and check reading on gauge. This will either tell gauge good or bad.

Since all of these electronic test suggestions scare me and don’t make sense… I would check the thermometer by pointing it at a pan of boiling water. Does it read 212F? What temp is your thermostat supposed to open…180F? I would just check those simple things first as the others scare me, lol. Good luck, you’ll get it right.

Try to measure the resistance between the sender case and the block with an ohm meter.

Maybe the lazer is not accurate. I would think 180 is perfectly normal.

Hi Barry, I took the temp vs ohms readings that you showed in the manual and made an Excel chart. It's not a straight line. I then extrapolated to your room temperature (approx. 80 deg F) and the ohms reading came out to almost exactly 836 ohms, which is what your test instrument cluster indicated. I don't see a problem there. When using an infrared temperature gun, you need to account for the emissivity of the material you are measuring. A flat black radiator hose will have a different emissivity than a shiny aluminum thermostat housing. You could easily introduce a 30 degree error between the two. I noticed at no time did you actually point the infrared temperature gun at the temperature sending unit on the engine (with the correct emissivity entered). I'd be interested to see what that reading would show. Bart '65 Impala SS

Did you try testing the ohms on your digital readout after the engine warmed up to operating temp ? My best guess would be that it also is not accurate. If the ohms where less then what your directions indicate they should have been for the temperature that the hand held thermometer indicated then I would believe that the problem would be the temperature sending unit

Might want to check the accuracy of Your temp. tool. I have two and they rarely read the same. What degree is the thermostat? If the engine was fully warmed up, the gauge on The dash seemed to be close to what it should be,where as Your laser tool was showing 140 more or less? That seems pretty low for a warmed up engine.

Did you check the ground to the main unit? Your temperature issue sounds similar to the issue I had with the fuel indicator in my 65. Recheck the ground for the temp sensor on the unit.

Maybe the lazer is not accurate.

Hi Barry, is there a offset that can be entered in the setup for the temp section? The sensor is changing resistance as the engine heats up so technically it is working. By using a multiplier in the software, you should be able to get it to read correctly.

No PCV hose ?

Is there a calibration screw (potentiometer) on the digital temp sensor which allows you to dial down the readout value? If not, perhaps you can add one inline to the wire which connect to the gauge. Or, can add a resistor inline to reduce the ohms by an amount which would correlate to a 30 degree lower readout on the gauge? It seems to make sense at colder than 100 temp the ohm value would be higher than 500. I was hoping that you were going to provide the ohm result from the gauge self-test when the engine reached max operating temperature. If you did, I don't recall you stating you had that value. If the ohms didn't drop to corresponding values on the chart, I believe that would indicate the water sensor needs to be replaced. And that is the first thing I would consider has failed, since we all know you do meticulous work.

Question about welders. I just returned an amazon welder today, totally unhappy with it. Did you have luck with yesweld? They actually have them in amazon out here in the UK, what do you think about them? If I buy them is there anyway I can get you credit?

You found the problem, just skipped over it... the resistance from the temp sending unit is off from what the computer is expecting, and reading... need to get one that reads what the manual stated for 100 degrees.. roughly, I believe it was off by 300 ohms...

Hi Barry, The manual mentions they only offer one temperature sensor. Did your sensor come in the kit?

I don't think it's the temp gun. As others have stated, 800+ cold would be expected. I have experience woth Dakota digital. Check with an ohm meter versus what the test tells you. Either the logic is off on how the processor is reading the ohms, or the sensor is bad. Just a note as others have said. If you used a sealer, remove it.

Jo Daddy how do I get to and secure down garage box behind slide on my 68 GTCS

Where did you ground your fuel sending unit? I can’t get mine to register after setting up

Did you use any sealant on the sensor ? If so, it may impede the resistance.

That is from your motor not the radiator hoses. Not the same temp at all. If your car is running at 140 its definitely to cold and highly.doubt it. After runing for 10 min it should be at 180

Ohms increases as the temperature goes down so 836 ohms makes sense for a cold engine, right?

Have you figured this issue out?

Have you tried another temperature sensor?

Did you get it fixed yet?

Did you ever get this issue figured out?

Sending unit

Sensor are cheap, put a new one in. Retest . Go from there.

No thank you, I'll stick with my "mechanical" gauges which are easy and have never failed me.

Just because it's new doesn't mean it's good sender

USA babby