3.3v signal for cts

Keith Diagnostician United Kingdom Posted   Latest   Edited  
Updated
Electrical
2009 Peugeot 308 1.6L 5-spd

Hello people, today I had a fault with a coolant temp sensor on a Peugeot 308 1.6 petrol, now whilst checking voltages etc, I noticed that the signal wire was only 3.3v and not 5v. I have since checked 2 other Peugeots with the same engine in and they are all 3.3v, I was under the impression that the signal would be 5v disconnected, anyone else had this???

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Keith Diagnostician
United Kingdom
Keith Update
   

I should also mention that I have checked the voltage at the ecu and its the same 3.3v even direct at the ecu pin with no loom attatched.

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Ray Diagnostician
Ontario
Ray
 

Looks like the 3.3v to the CTS is ok. What is the code? Is the CTS temperature the same as the Air Temp Sensor on a cold engine? Is there continuity between the other CTS wire to the ECU? Is the thermostat opening too early. Ray

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Keith Diagnostician
United Kingdom
Keith
 

Hi the fault was CTS short to earth and at around 60c it would would drop out to -30 , the thermostat housing was new and this it the 3rd CTS that i have fitted i have checked the wiring integrity and that was all ok. J have since put a different brand CTS in and all is ok at present. J was just concerned with the 3.3v disconnected as I assumed it would be 5v .

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Jason Instructor
Pennsylvania
Jason
 

I remember from my days at a Kia dealership that there were a few models (cant remember exact ones) that used 3.3v as a reference voltage. Totally normal but can be confusing for a technician who was expecting to see 5v. I never did look to see who manufactured the ECM for those vehicles but could possibly be the same compnay making the Peugeot ones.

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Keith Diagnostician
United Kingdom
Keith
 

Thanks for the reply Jason I will remember this lol, what made it more confusing for me was that some technical data i had said it will be 5v but now I know it's incorrect . The engine In question is a 1.6 ep6 5fw peugeot engine which is fitted in the Bmw 1 series and the bmw mini aswell.

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Mark Technical Support Specialist
United Kingdom
Mark
 

Peugeot data lists this voltage on this 1.6 5fw engine as 3.3volt - this is checking circuit voltage from inside the engine ecu

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Keith Diagnostician
United Kingdom
Keith
 

Thank you mark for confirming this .

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