i have a 2001 pt crusier non turbo. the temperature is fluctuating between cold and over heating.
i have a code of p0118 which indicates an overvoltage from the sender.
and it is correct i am getting 10volts across the sender wires.
i replaced the sender first. then checked the voltage so i thought it was the ECM

i replaced the ecm and i still have the same problem

i cannot find the ecm pin out online but the two wires from the sender are going back to the ecm
one should be 5volts out to sender and the other should be the return

i can not see where the wires are shorted to any other wire

any ideas where i should look

thanks

 

across the sensor what do you mean by that? 2 wires 2 separate voltages will be present. Tell me the wire color and which wire had which voltage with the key on.

 

two wires going to temp sender
black with blue stripe
and tan with black stripe
with ignition on the tan with black has a alternating voltage 0 then 10 volts and cycles every few seconds
the black with blue 0 volts
both are measured to ground

 

ok the black and blue wire is you issue there should also be voltage on that wire. trace it down to the pcm im betting there is a break at a splice

 

ok so i am trying to track the black with blue wire but somewhere it changes color on the way back to the pcm
also it appears to be crossed with a ground

what pin should the wire go back to on the pcm and i will jumper it

do you have the engine wiring diagram for the 2001
thanks for your help

 

The wire goes into a splice for other sensors. that wire is called the 5 volt reference signal. goes to a whole hose of other sensors like map, knock air inlet cam crank. pull of of thoes sensor and measure that same blue black wire see what voltage you get there. That's what you want also on the coolant temp sensor. if the other sensors are showing X you want the same. And if you had a wire back to the pcm issue then the other sensors would also be throwing codes along with the coolant temp.

 

So here is what i finally did at it appears to have fixed my problem
i found a set of wiring diagrams for the pt and checked the two wires
tan with black went straight back to the pcm
black with the blue (turns out it was lt blue) went back to ground
i cut the tan wire at the sender and the pcm and checked voltage out from pcm which was 5 volts I jumped the wire back to the temp sender now everything is ok

strange thing is the tan wire now has no voltage on it which makes little sense to me
anyhow seems fixed now i will just cross my fingers nothing else happens