AMC86Kid

ok i will check for power because they don't move when you turn the vehicle back on thanks

ok the gas is at the middle and the oil dosent move its at the low end

Can anyone explain or give me a link to how my RPM gauge should work mine stays at 4k on idle then bumps way up when i press the gas

Eagle i have not tested the gas and oil pressure gauge yet just trying to figure out the temp and RPM gauge for now but yes i will post a new thread for the RPM gauge here: https://comancheclub.com/forums/topic/53947-86-28-rpm-gauge/ also no luck on my temp gauge i think i will just use the after market one i got it works fine but i will try to figure out exactly how the wiring goes when i take my dash apart later

i don't understand what it means i get that Tachometer inoperative means the RPM gauge but what does it mean by AC voltage under OK ??

i did what eagle said and i still get the same results thought that maybe by not powering them up a the same time would change the out come but no you get the same outcome oh and here is a pic of the whole back it looks fine to me

ok so i tried playing around with it again and this is what i got out of it i can move the needle as i turn the pot but its on the wrong side of the gauge

johnj92131 i get what you mean by having apposing poles to get it to balance out but what i can't do is send separate polarities to the 3 prongs for example lets say you have prong 1 prong 2 prong 3 if 12 volts is applied from prong 1 positive to prong 2 negative it moves one way but if prong 2 negative and prong 3 positive are applied the same 12 volts it moves in the same direction the only way i can get the second connection (prong 2 and 3) to turn the other way is to switch the polarity but then the problem is how can prong 2 be both negative (for circuit 1) and positive (for circuit 2) at the same time Eagle i am using a 1K Pot so i can turn it and i should be able to get the needle to move almost all the way but not fully Green Mesa XJ I'm just tying to see if i can get the original gauges to work if not then at least i tried and i will replace them with aftermarket ones i got the after market water temp gauge to work but i will get a IR thermometer and see if the data its telling me is accurate guess thats all i can do for now until my new electric fan shows up oh and do you have any idea how the RPM gauge works ? in my 4th pic you can see it uses 3 prongs

Eagle not sure if you missed it but in my third Pic i have an small gas gauge and a large RPM gauge however my RPM gauge does not work (and that might be why the temp gauge dosent work either its a possibility) my rpm gauge sits around 4,000 RPM when my engine is at idle, then when i press the gas it goes way up as of the 4th pic yes i do see the upper on does connect to the RPM gauge (not sure how rpm gauge works havent got there yet) yes the middle one is connected to the lights so it must be positive 12 or ground and yes i see the bottom one goes to a direct wire i have tried to connect the gauge to a bread board and connect it to a battery and use a potentiometer to see if i can get the needle to move but all i can do is get the needle to move fully one way then when i reverse the polarity it full moves the other way no matter which two prongs i make connections with the negative terminal and one with a positive terminal i can't get it to balance anywhere in the middle of the gauge regardless of how much resistance i set it to

ok i went back and read it so from what i got it has two poles that move the needle either left or right but when both are on at the same time it balances the needle in between the temp sensor is like a potentiometer and all it does is change the resistance to the gauge when the gauge then balances out and displays what the temp is however i also see that the gauge must then be current controlled because the gauge must get 12 volts (since its connected in parallel with the lights in the dash) and the temp sender changes the resistance of that 12 volts threw the gauge which then limits the amount of current passing by one or the other poles still not sure which prong is the H-Coil and which is the C-coil

Jeep Driver i don't remember if i stated it in my last post or not but i fixed the water flow problem it was the thermostat and i replaced it with a 180 my current problem was i could not read the temp of the motor as it was running i hooked up an after market temp gauge, this one : https://www.oreillyauto.com/detail/equus-3541/agriculture-hd-parts---accessories-19818/fleet---heavy-duty-20088/instruments---gauges-20107/gauge---water-temperature-17811/water-temperature-gauge/6262/4299448/1994/pontiac/firebird ran the motor for about 10 minutes and got it to go up just past 200 i need to get another cooling fan, i only have one in front of the rad i don't have one for behind it yet theres a quick update for you i was asking questions about this temp gauge because if i could get it to work then i will have two connected to the motor so if one fails and the other dosent i will know immediately but so far i can only get the new one to work and I'm not 100 percent sure on how acurate it is so i think I'm going to go and pick up a Infrared temp gun like you said if the temp gun says 200 degrees on the surface of the motor and the new temp gauge says 200 as well then i know that the new temp gauge is off because how can the inside of the motor be the same as the outside i should be warmer but I'm not sure by how much

so the gauge is current and resistive controlled dam that sucks i was definitely sending resistance to it but i have no clue how much current to send it have you ever tried to take one of your gauges and tried to wire it and see if you could get it to work outside of the dash if you can figure out how it works then i can test mine the same way all i could figure out is that one terminal gets 12 volts positive and I'm not 100 percent sure on the other two pins but they must get some sort of resistance and which fuse should i check cause theres a lot of them

ok i have started a new post since this is a new topic maybe someone else can help us https://comancheclub.com/forums/topic/53897-1986-28-water-temp-gauge/

ok i have removed the dash and took the temp gauge out of the dash like so notice it has 4 connectors on the back however only 3 of them are used on the mother board now that i have it removed i should be able to completely bypass all the wires I'm unsure of and connect it straight to the temp gauge but I'm not sure exactly how the three prongs should be connected i have this temp sensor http://www.autozone.com/engine-management/temperature-switch/duralast-temperature-switch/129205_385179_15458?&searchText=tu66 i have also tested it with an ohm meter and the sensor does work i have tinkered around and got the needle to move far right and far left but no luck on getting it to respond to the temp sensor properly does anybody know how this gauge should work? if not i guess i will just go buy a new gauge

ok so i connected an ohm meter to the new sensor and its telling me around 1580 ohms which is around 100 degrees so my sensor is working properly but my gauge is not when you say "one wire connection with the engine acting as ground" do you mean that the gauge is connect to the engine and the red wire to the sensor that might be my problem i may not have my engine grounded properly i have the negative terminal connected to the engine from the battery but shouldn't i have some wire from the firewall connected to my engine do you know which one or what color wire should be grounded to the engine if the gauge works on resistance from the sensor i have to have it connected by at least two wires so far i can only confirm that the red wire is connect I'm not 100 percent sure on how its grounded to the motor

Ok so I can get a temp sensor and screw it in that's not a problem but how does the temp gauge in the dash work or how can I install a new one to the sensors I have do you think I should start a new post on "86 temp dash gauge how does it work"

ok so here is where I'm at i got a new temp sensor this one: http://www.autozone.com/engine-management/temperature-switch/duralast-temperature-switch/129205_173479_10199_5673?&searchText=tu66 the guy at autozone told me that its an OEM equivalent to the AcDelco 21380 i screwed it in and connected the red wire and ran my motor with no luck the gauge in the dash stayed at 100 degrees i do believe that this is the correct sensor to use however i do not know how the gauge in the dash works it could be something simple like my gauge is not grounded or my vehicle is not grounded properly but who knows also i found this remember the hole in the corner that you were talking about it looks like the 2.8 sensor would screw into it since the hole appears smaller http://www.rockauto.com/en/moreinfo.php?pk=930679&cc=1181393&jsn=384 but of course i would have to connect it to my gauge in the dash and i don't think it would work anyways so at this point id say i should get a new gauge and try to hook it up to one of my temp sensors any suggestions on what gauge i should get and how to hook it up so i can get a good measurement at what temp my engine is running at

when you say 20/80 mix do you mean 20 coolant to 80 water mix also i called orileys and they don't sell the ACDelco 21380 temp switch but they crossed referenced it to this https://www.oreillyauto.com/detail/bwd-3123/lighting---electrical-16777/switches-16486/a-c-switches-16500/coolant-temperature-sensor-sender-switch-11362/temp-sender-gauge/wt359/2617460/1994/pontiac/firebird?q=Wt359 my only concern is the part where it says this: Temperature Range (Deg F): Closed At 100 Degree, Open At 220 Degree does that mean it will only keep track of my engine temp up to 220 and then it won't go any higher?

yes i have learned that it gets over 180 degrees because i had to buy a new thermostat thats rated at 180 but how hot is the radiator allowed to get because mine gets pretty hot and i added a big fan maybe the coolant to water ratio is not 50 /50 and thats why it gets warm very fast

hmmm well that sucks I'm hoping somebody would actually know that way it would save me the pain but i guess i will buy it at orileys and return it if i can't get it to work so theoretically i can get the sensor replace it where one of the other sensors are connect the red wire and then see if my temp gauge responds correctly guess that will be my plan is this it right here https://www.amazon.com/ACDelco-213-80-Original-Equipment-Temperature/dp/B000C9L7DI how do you connect the red wire to it?

Can you post a link of that sensor is it the same one in your pic

thats what rock auto has under 2.8 what sensor do you think it should be

is this the 2.8 temp sensor http://www.rockauto.com/en/moreinfo.php?pk=930679&cc=1181393&jsn=731&jsn=731 do i just connect the red wire to it and it should work what do you think ?

no i don't have the 2.8 engine just a few parts from it but i do agree with you that the red wire goes to the gauge maybe i just have to pull the coolant sensor out and screw in the correct sensor in its place then connect the red wire but I'm not sure what the correct 2.8 sensor that would be

ok so after tinkering around i had connected these two wires like you said i tried to both sensors but could only get a response with the way its currently hooked up and i was able to get the temp gauge to move from 100 to this do you guys think i figured it out ?? how can i be sure i have it hooked up correctly i sure wish i could find some info on the two prong sensor so i could read up on it and see exectly what its made for