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AEM issue with Coolant temp sensor

Bimmubishi

Well-known member
Joined
Jul 15, 2003
Messages
5,702
Location
Boston, Massachusetts
I'm struggling here with a 1g. It's got AEM EMS. We have a new coolant temp sensor in the T stat housing, have checked both wires for continuity to the ECU and the temp on the laptop states 217 degrees at room temperature.

Disconnecting the 2 pin spade connector from the sensor yields a 2 degree fast fluctuation between 217-219

Jumping the pins on the terminal of the harness makes the temp jump to 176f and hold constantly.

Am I looking at a faulty ECU?

I've never had luck with AEM.

Suggestions please... (the sensor type is set to Mitsubishi)

Thanks,

Alex
 

Bimmubishi

Well-known member
Joined
Jul 15, 2003
Messages
5,702
Location
Boston, Massachusetts
I did. It has the same resistance as the used one I took out. (don't remember offhand what it was) But.. if you look at my troubleshooting method above it's not the sensor.. it stays at 217 with no sensor plugged in! /ubbthreads/images/graemlins/smile.gif
 

CSMShaun

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Joined
Jan 2, 2010
Messages
129
Location
Cincinnati, OH
I am not familiar at all with AEM. I know the factory ECU looks at Ohms of resistance to determine temperature. If the wires are new, you tested the sensor with a multimeter and a temperature source and the settings inside the ECU are correct then I am at a loss as far as what you should do next. LOL Sorry to take up your time.
 

It sounds like you need to setup your sensor on the ems.

From AEM Pro:
Setup -> Sensors -> Coolant Temp Sensor -> Coolant Temp Wizard

Just select Mitsubishi all in there. If that does not fix it then, you will need to get a volt meter and test the output voltage. At fully warmed up it should be like 0.62v-0.78v.

Also if you look under

Setup -> Sensors -> Coolant Temp Sensor -> Options - CLT Sensor

I would bet that your Coolant Failsafe is set at 217.
 

Bimmubishi

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Joined
Jul 15, 2003
Messages
5,702
Location
Boston, Massachusetts
Thanks theboz-

We checked those things. I think that the failsafe is really high for the time being... at like 274 or something. The sensor type is for Mitsubishi.
 

Check the voltage going to the sensor and the voltage going out of it. Also how old is the sensor, did the sensor work before?

Are you pluged into the correct sensor, check the wireing, the wires to the temp sensors break a lot.
 

Armitage

Well-known member
Joined
Oct 16, 2003
Messages
715
Location
Herndon, VA
You're not using the factory engine harness are you? According to the wiring diagram, the coolant temp sensor wire splits off and goes to visit the TPS and EGR. If there's a short in the harness somewhere (like I suspect mine has), you may get some unpredictable readings. I get sporadic CELs and idle hunting even though I've got continuity at the sensor end.


 
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