Trouble Code P 0340
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Trouble Code P 0340
1999 F-150 4.6L 130k mi.
I am getting a intermittent trouble code for Cam Sensor(P0340).
I have already replaced the cam sensor twice.
I am going to assume it is a wiring problem. Does anybody know if there is a wiring harness section that I can replace. I know this is probably going to be a tough job.
Anyone else been through this?
Thanks in advance.
I am getting a intermittent trouble code for Cam Sensor(P0340).
I have already replaced the cam sensor twice.
I am going to assume it is a wiring problem. Does anybody know if there is a wiring harness section that I can replace. I know this is probably going to be a tough job.
Anyone else been through this?
Thanks in advance.
Hotshot
Joined: Aug 2002
Posts: 12,679
Likes: 15
From: BC, Canada
Trouble Code P 0340
The only connector in the wiring between the CMP and PCM is the big one behind the cover over the starter relay etc on the firewall.
The best way to diagnose the wiring would be to hook up a breakout box (a dealer only item usually) and check the resistances. If the wiring all checks out ok you could have a PCM problem too.
Did you use genuine Ford CMPs?
How long does it take to set the code?
The best way to diagnose the wiring would be to hook up a breakout box (a dealer only item usually) and check the resistances. If the wiring all checks out ok you could have a PCM problem too.
Did you use genuine Ford CMPs?
How long does it take to set the code?
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Trouble Code P 0340
The first time I replace the cam sesnor I used Genuine Ford, the second time was with an Autozone special.....
The code will come on and last a day or so and then reset itself. Then it could take weeks to come on again. I do know that temperature is a factor. The problem seems to occur when the weather is hot and after I have driven a long distance(1 hour or so.) and everything is hot under the hood.
I wish I knew more about how the computer diagnoses the circuit malfunction. If there was a open circuit, how would the engine continue to run without have a cam pos. sensor signal. Can it sense a change in the resistance i.e. a patially broken wire?
Thanks for the info.
The code will come on and last a day or so and then reset itself. Then it could take weeks to come on again. I do know that temperature is a factor. The problem seems to occur when the weather is hot and after I have driven a long distance(1 hour or so.) and everything is hot under the hood.
I wish I knew more about how the computer diagnoses the circuit malfunction. If there was a open circuit, how would the engine continue to run without have a cam pos. sensor signal. Can it sense a change in the resistance i.e. a patially broken wire?
Thanks for the info.
Hotshot
Joined: Aug 2002
Posts: 12,679
Likes: 15
From: BC, Canada
Trouble Code P 0340
Here is what the manual says about a P0340.......
P0340 - Camshaft Position (CMP) Sensor Circuit Malfunction -
The test fails when the PCM can no longer detect the signal from the CMP sensor.
Possible causes -
CMP circuit open
CMP circuit short to GND
CMP circuit short to PWR
SIG RTN open (VR sensor)
CMP GND open (Hall effect sensor)
CMP misinstalled (Hall effect sensor)
Damaged CMP sensor shielding
Damaged CMP sensor
Damaged PCM
Diagnostic aides -
Harness routing, harness alterations, improper shielding, or electrical interference from other improperly functioning systems may have intermittent impact on the CMP signal.
If the PCM doesnt see a signal from the CMP it "fakes" it. Supposedly with no signal the PCM will plug in different timing settings until it finds one that works. At least I think that's what they taught us in school
P0340 - Camshaft Position (CMP) Sensor Circuit Malfunction -
The test fails when the PCM can no longer detect the signal from the CMP sensor.
Possible causes -
CMP circuit open
CMP circuit short to GND
CMP circuit short to PWR
SIG RTN open (VR sensor)
CMP GND open (Hall effect sensor)
CMP misinstalled (Hall effect sensor)
Damaged CMP sensor shielding
Damaged CMP sensor
Damaged PCM
Diagnostic aides -
Harness routing, harness alterations, improper shielding, or electrical interference from other improperly functioning systems may have intermittent impact on the CMP signal.
If the PCM doesnt see a signal from the CMP it "fakes" it. Supposedly with no signal the PCM will plug in different timing settings until it finds one that works. At least I think that's what they taught us in school
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