3.3v signal for cts

Keith Diagnostician Clevedon, United Kingdom Posted   Latest   Edited  
Question
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
Clevedon, United Kingdom
Keith
   

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
North York, 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
Clevedon, 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
Nanticoke, 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
Clevedon, 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
Wheatley, 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
Clevedon, United Kingdom
Keith
 

Thank you mark for confirming this .

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