5.4L OBD Code P1451
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From: Louisville,Ky.
The EVAP system monitors the canister vent (CV) solenoid circuit for an electrical failure. The test fails when the signal moves outside the minimum or maximum allowable calibrated parameters for a specified canister vent duty cycle by PCM command.
A code P1451 may mean that one or more of the following has happened:
* VPWR circuit open
* Damaged canister vent solenoid
* Canister vent solenoid circuit open or shorted to ground, power, etc.
* Damaged Powertrain Control Module (PCM)
* Verify canister vent solenoid - To verify normal functioning, monitor the EVAP canister vent solenoid signal PID EVAPCV and the signal voltage (PCM control side). With the valve open, EVAPCV indicates 0% duty cycle and a voltage approximately equal to battery voltage. When the valve is commanded fully closed, EVAPCV indicates 100% duty cycle, and a minimum voltage drop of 4 volts is normal. Output test mode may be used to switch output on/off to verify function.
* Replace canister vent solenoid
A code P1451 may mean that one or more of the following has happened:
* VPWR circuit open
* Damaged canister vent solenoid
* Canister vent solenoid circuit open or shorted to ground, power, etc.
* Damaged Powertrain Control Module (PCM)
* Verify canister vent solenoid - To verify normal functioning, monitor the EVAP canister vent solenoid signal PID EVAPCV and the signal voltage (PCM control side). With the valve open, EVAPCV indicates 0% duty cycle and a voltage approximately equal to battery voltage. When the valve is commanded fully closed, EVAPCV indicates 100% duty cycle, and a minimum voltage drop of 4 volts is normal. Output test mode may be used to switch output on/off to verify function.
* Replace canister vent solenoid
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New User
Joined: Jul 2005
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From: Northeast Pa.
I tested the cv sensor and got 54 ohms. I then tested the wiring harness from the cv sensor which showed only 2.59 volts. Do you think its a short, or should I pull the pcm and test the related pins?
Hotshot
Joined: Jan 2004
Posts: 19,762
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From: St Louis
It's probably not a short. It is far more likely that it is a bad connection, usually due to corrosion in the connector, causing a high resistance circuit.
What wire did you measure that on (there are two at the solenoid) and was that with the solenoid connected or not?
Steve
What wire did you measure that on (there are two at the solenoid) and was that with the solenoid connected or not?
Steve
Last edited by projectSHO89; Mar 8, 2006 at 08:44 AM.
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New User
Joined: Jul 2005
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From: Northeast Pa.
I stuck my voltmeter in both wires at the solenoid connection wire harness. Then I checked the ohms at the solenoid connection. Will this code make the truck run any different? Thanks
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From: Northeast Pa.
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Hotshot
Joined: Jan 2004
Posts: 19,762
Likes: 1,079
From: St Louis
Measure from each pin to ground separately with the solenoid connected. With the solenoid de-energized, you should measure battery voltage on both wires. With the solenoid energized, you should show battery voltage on the R wire and near 0 Vdc on the P/W wire.
The CV solenoid is only for the evap emissions system. It won't affect engine operation. If you have emissions testing requirements where you live, it will automatically fail.
Steve
The CV solenoid is only for the evap emissions system. It won't affect engine operation. If you have emissions testing requirements where you live, it will automatically fail.
Steve
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