JDMEnthusiast

sup guys...... i just swap my engine to a JDM 13BTT in my FD's and the car run great. the only thing is the water temperature gauge is not working, so i can't tell it is worm or hot. im thinking maybe i might forgot to to plug in some wire, but i don't know where it is. would any one happen to know where it is or what is wrong (temperature is not reading). thanks.

scotty305

iTrader: (2)

The stock water temp gauge isn't very accurate anyways. Are you using a stock ECU? If so, the important thing is that the fans come on when the car gets to a certain temperature. Try idling it for a while with the headlights on. The fans should kick in within 5 minutes, maybe 10 mins if the car is very cold when you start it.

The wire to the temperature sender for the gauge is near the spark plugs, it's a single-prong connector.

-s-

GARCO MOTORWORKS

Yes on the spark plug side,foward from the oil pressure sending unit,about 1-2 inches . A small senser with a single spade connector .The wire to it is yellow with a white tracer .

No-Pistons-TT

does your car have problems starting ??? the stock ecu uses temperature info to start the car. mines busted and it takes a few tryes to turn over i have a new one on order though. there are 2 temp sending units btw.

MichaelFregoe

iTrader: (1)

The water sensor for the ECU is different than the one for the gauge.

I just bought an aftermarket gauge for water temp and it is by far the best (most satisfying) mod I have purchased in recent memory. Bottom line is that I LOVE it. Being able to see the exact temperature as the car gets warmer and cooler seems like a small thing... But very reassuring.

mecman

iTrader: (11)

Check the connection to the sensor per GARCOs post. My sensor died and it was simple to replace. It came out with a socket wrench and put the new one in, reconnected the wire and it works.

I have since put on an autometer temp guage since the stock one is not linear in the temp readout. I have every reliability mod EXCEPT a new radiator. So far my temps have not exceeded 210 F in 90 plus weather in stop and go driving. It drops down to 190 once I am moving.

rotarypower101

iTrader: (1)

Hey guys what are the reasons this gauge fails?
Is it easily repairable or is it a replace only type item?
AFAIK the sensor and wiring are all new and fine, so I am fairly sure this is not the issue.

Can anyone give me an executive summary of where their problems lye with this item and what was you fix?

I have no desire to supplement/replace the stock gauge for an aftermarket unit, really just dont want a broken gauge on my cluster, regardless of how inaccurate or undependable the unit is. I have other means of keeping my eye on my water temps and this is not the issue. I just cant stand a non working gauge even if non trivial.

Any good threads/links someone has found that give an indepth look at repair and diagnosis of this unit and system?

TIA

DeAd-EyE

iTrader: (1)

My understanding is that the stock water guage is weighted to the center for some reason, so by the time it does move off the default setting, it's already too late and you're motor is likely kaput.

If you look in the 3rd gen sub forum in the FAQ thread, there is a way to mod the stock doohicky to work properly.

EDIT: Here you go - https://www.rx7club.com/3rd-generation-specific-1993-2002-16/temp-guage-inaccuracy-252334/

rotarypower101

iTrader: (1)

Not really trying to linearise it or make the gauge more accurate at all.

My gauge is not working, which again is not what I use for my water temperature (so no big deal), I just really dont like the fact that it is a dead gauge on a otherwise functional cluster.

Not finding any threads dealing with non working or dead gauges and was hoping someone could provide some insight on a plan of attack, whether it be just replacement or if there is perhaps just an easy fix.(which a lot of the time is the case in an aging car fortunately )

Does the sensor go bad? Any quick tests I can do to test this sensor?

I can only assume the wiring from the sensor to the gauge is intact as everything else works as designed.

Can the contact on the instrument cluster or an intermediate point cause trouble?

Or is it more typical of the gauge to fail somehow? And what is the normal mode of failure?

TIA

JDMEnthusiast

back in "05" if you notice the date from my original post, i found out what's the problem for my car. it's because im using my in dash harness (us) with a JDM ecu so what i have to do was rewire couple of the wires (simple fix the problem). now other common problems is either the sensor is bad or wire is open (i came across that once). temp gauge is rarely good bad on a FD but of course nothing is perfect in this world. you can search in this forum for some simple steps on how to test the sensor because im pretty sure i saw some posts in the forum a while ago. i hope this will get you start some where good luck

CloudPump

iTrader: (2)

What are your other methods of keeping your eye on your water temperature?

-Geoff

NEWGENRX7

what engine harness did you use us or jdm? if you used jdm harness. all you have to do is find the single black connector and splice it and make the wire longer and connect it to the the temp sensor by the spark plug side and foward from the oil pressure sending unit.

rotarypower101

iTrader: (1)

This question was not JDM harness specific, just tacking on to a similarly topics thread as not to cause to much clutter. It is jus ta generic help request for the same item.

My harness is new USDM so absolutely no issues with a JDM harness

Thanks though.

Any help tracking down these threads, still have not found any useful topics dealing with testing the stock water temp gauge system, and diagnosing a solution.

It would seem the only advice it to replace it with a “more accurate” system in lieu of repair or requesting a working gauge.
Its not OCD, I just dont like a broken gauge, and I notice it every time I peek down at the cluster!

Maybe if the needle was at half staff I wouldn't notice it so much but as it is it is dead below the lowest reading, my eye catches it every time

rotarypower101

iTrader: (1)

I use datalogit outputs for all important gauges, on what is jokingly referred to as a carputer on a 7” touch screen.

But I would much rather have used this as it is very user friendly and a ascetically beautiful presentation.
(a tip of my hat my friend, please finish it!)

http://www.youtube.com/watch?v=qqaf6EXhxOI

http://www.youtube.com/watch?v=mGCz6keXw5s

rotarypower101

iTrader: (1)

Thanks but entire system is USDM

rotarypower101

iTrader: (1)

The FSM and electrical system has testing procedures to test both the sensor and the gauge.

Any tips on how to test the gauge without the SST?







TIA

scotty305

iTrader: (2)

That sensor, like most other temperature sensors, is essentially a variable resistor. The resistance will change depending on coolant temperature.

You could disconnect the plug from the sensor and connect a resistor in place of the sensor. 100 ohms should make the needle move to the center of the gauge (about 180F), 20 ohms should make the needle move toward the 'H' mark. One side of the resistor connects to the wiring harness, the other side of the resistor will need to connect to ground (battery negative post).

If the sensor is disconnected from the gauge (or the wire is broken between the gauge and the sensor) the gauge will always indicate Cold. If the sensor or wiring is shorted to ground (zero resistance between the sensor wire and ground), the gauge will always indicate Hot.

rotarypower101

iTrader: (1)

Hey thanks!

The resistance of the thermistor sensor checks out fine and seems to be right in the range dictated by the service manual (no surprise considering the simplicity of its construction)

So like I said I think the sensor is fine (was tested before assembly and does not have very many miles on it), but I still am not seeing any movement what so ever or readings on the gauge.

I will throw a appropriate resistor in line just to see if something weird is happening (these things seem to happen to me in particular a lot where even experts say no its not that it couldn't be....and more than a few times the problem was a very very obscure issue )



Now here is a little thing that has gotten me paranoid....is it possible I received a JDM engine harness as the other posters had mentioned? Is there a way to confirm a JDM vs USDM harness?

There is a single black female (unused) spade connector on my new engine harness (residing down next to the ecu/PFCs main yellow connectors under the US passenger kick panel) that I have never quite found out its purpose but was instructed it was for “nothing dont worry about it” could this be the “single black connector” that you guys are referring to “find and splice it and make the wire longer and connect it to the the temp sensor” could it be?

Is there a way to test the gauge without the SST to rule out a malfunctioning gauge ?

Also is there a thread dealing with the repair or solution to using a JDM harness and wiring in a jumper to the block thermistor?

rotarypower101

iTrader: (1)

Hey NEWGENRX7 can you lead me to the thread or info where you learned of this fix for a JDM harness?

I want to look into the possibility that I may have a JDM harness, of which I disregarded before.

Perhaps that is in fact what I received and just was not informed of such. The harness was purchased from Malloy, so I would make the assumption that it would have to be a USDM harness, but I guess I should look into the possibility that it may not be.

Is there a way to discern the difference between the two harnesses? JDM vs USDM?
Any tell tale differences?

And more importantly, where is the “single black connector” that you guys are referring to “find and splice it and make the wire longer and connect it to the the temp sensor” located at for the JDM harness?

Because when you say there is a single black connector, the wheels in my head started turning and I recalled there is a single black unused female spade connector under the passenger kick panel by the PFC. Is this the location of the connector you are referring to?

NEWGENRX7

sorry for the late response but did you figure it out?

Slissek

What about for the coolant alarm? Mine keeps coming on after 10 min or so. already replace the thermostat and thinking of replacing the water pump. the engine dosent get that hot and the radiator is not warm.

CloudPump

iTrader: (2)

The low coolant alarm is the wire coming from just below your coolant filler cap. The alarm goes off if the sensor is not being grounded out through contact with coolant.

-Geoff