Too much voltage...
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Too much voltage...
I am in the process of troubleshooting an EGR Excessive / EGR Insufficient (P0400 and P0401) set of codes when I noticed that I am getting too much voltage at the collant temp sensor.
At the wiring harness of the Engine Coolant Temp Sensor, I am told that I should be getting appx 5 volts. I am getting 12.1 volts.
I am very new to this so I am needless to say, at a loss...
At the wiring harness of the Engine Coolant Temp Sensor, I am told that I should be getting appx 5 volts. I am getting 12.1 volts.
I am very new to this so I am needless to say, at a loss...
Post Fiend
Joined: Jan 2003
Posts: 9,748
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From: Connecticut
Too much voltage...
Might want to read through these recent threads:
P0401 Code Check Engine On
P0401 EGR flow insufficient?
P0401 Code Check Engine On
P0401 EGR flow insufficient?
Post Fiend
Joined: Jan 2003
Posts: 9,748
Likes: 16
From: Connecticut
Too much voltage...
Ford Says:
Based on the above, like Bob suggests, maybe you measured the wrong side of the plug showing voltage that has not yet been affected by the resistor? Also, the information I have is that the max voltage reading on the ECT sensor should be no more than 4 volts when the engine is cold, and it goes down from there as the engine heats up.
The engine coolant temperature (ECT) sensor is a thermistor device in which resistance changes with temperature. The electrical resistance of a thermistor decreases as the temperature increases, and increases as the temperature decreases. The varying resistance affects the voltage drop across the sensor terminals and provides electrical signals to the PCM corresponding to temperature.
Thermistor-type sensors are considered passive sensors. A passive sensor is connected to a voltage divider network so that varying the resistance of the passive sensor causes a variation in total current flow.
Voltage that is dropped across a fixed resistor in a series with the sensor resistor determines the voltage signal at the PCM. This voltage signal is equal to the reference voltage minus the voltage drop across the fixed resistor.
Thermistor-type sensors are considered passive sensors. A passive sensor is connected to a voltage divider network so that varying the resistance of the passive sensor causes a variation in total current flow.
Voltage that is dropped across a fixed resistor in a series with the sensor resistor determines the voltage signal at the PCM. This voltage signal is equal to the reference voltage minus the voltage drop across the fixed resistor.
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Too much voltage...
Rockledge,
Thanks for the insight. Here is what I have come up with. As far as the voltage issue, you're gonna laugh.... I was checking the wrong component! I (not having my coffee this a.m.) unplugged the injector that is right next to the coolant sensor. Once I checked the CORRECT piece, all good!
I looked at the 2 threads that you sent me and I am gonna take another look at my sensor. According to Haynes, the voltage should be no higher than 10 V. I am at 10.5 so I am going to replace just to say that I did.
Every other component came up roses so this would be the only piece that varies at all.
Thanks again for everyones help!!!
RG
Thanks for the insight. Here is what I have come up with. As far as the voltage issue, you're gonna laugh.... I was checking the wrong component! I (not having my coffee this a.m.) unplugged the injector that is right next to the coolant sensor. Once I checked the CORRECT piece, all good!
I looked at the 2 threads that you sent me and I am gonna take another look at my sensor. According to Haynes, the voltage should be no higher than 10 V. I am at 10.5 so I am going to replace just to say that I did.
Every other component came up roses so this would be the only piece that varies at all.
Thanks again for everyones help!!!
RG
Post Fiend
Joined: Jan 2003
Posts: 9,748
Likes: 16
From: Connecticut
Too much voltage...
Here's a little more info on the Engine Coolant Temperature sensor which follows up on my earlier post.
The reference wire that carries the 5 volt signal to the sensor will only read 5 volts if the sensor is disconnected. Any time the sensor is connected properly and the sensor ground is good, the 5 volt reference drops immediately. Usually, the voltage will be anywhere between 4 volts (very cold) to around .5 volt when the engine is fully warmed up.
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Joined: Aug 2003
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Too much voltage...
working through p0401 on 97 expedition 4.6L. Have replaced EGR valve & DPFE but still getting p0401. Found this info.
http://www.fordscorpio.co.uk/egrmonitor.htm
It is for a ford scropio appears to be shop manual for EGR system.
All of the pieces look very similar to my Expedition. Some good descriptions and trouble shooting tips.
Hope this info might help someone.
Good luck
http://www.fordscorpio.co.uk/egrmonitor.htm
It is for a ford scropio appears to be shop manual for EGR system.
All of the pieces look very similar to my Expedition. Some good descriptions and trouble shooting tips.
Hope this info might help someone.
Good luck
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