LOST JEEPS :: View topic - any fuses I should check?

maxximr wrote:

thanks but I tested the wiring and it's getting electricity, my conclusion is I have two bad FCVs... yeay me! now if only someone could point me to where I could get them repaired or where I can get a buy one get one free deal?

How do you know it is getting electricity?
From what I can see in the circuit diagram....you will always have +12 volts on one side of the FCV via fuse 16 when ignition is ON.

The other side of the FCV is switched to ground by the ECM.....it is actually pulsed PWM I think.

So in other words if you are measuring +12 volts on one side with your meter ground lead going to the chassis it does not mean much.

On one of your spare FCVs put +12 volts on one side and touch ground briefly to the other side to see if it moves.

Edit to add: As papaindigo states....take out the butterfly altogether.
The only thing this valve does is give a smoother shutdown.....the 2002 (like mine) to 2004 models have survived quit well without a FCV fitted.

Author:	maxximr [ Wed Aug 08, 2012 5:53 pm ]
Post subject:	any fuses I should check?
I took out my fcv/throttle body today on my 2006 CRD Liberty, but kept it plugged in to test it, I turned on the engine then started the engine and it didn't move or buzz or do anything, so before I determined that it's broken I plugged in another fcv/throttle body and turned on the engine, then started it, same result: nothing. I could move the vent with my hands, and even close it, but if I close it and it's in stalled it blocks air and the engine won't even start. So I'm wondering is my wiring bad somewhere? or is there a fuse I could check first? (forgive me if I'm re-posting)

Author:	maxximr [ Wed Aug 08, 2012 6:29 pm ]
Post subject:	Re: any fuses I should check?
I tested the electrical, it seems to work..could both the fcv/throttle body valves that I'm trying be compromised?

Author:	papaindigo [ Wed Aug 08, 2012 8:39 pm ]
Post subject:	Re: any fuses I should check?
On an O6 check for chaffed wires in the bundle behind the fuel filter mounting plate or you could just remove the FCV butterfly (2 small screws IIRC) and forget about it (don't recall if that throws a constent CEL though)

Author:	maxximr [ Wed Aug 08, 2012 9:17 pm ]
Post subject:	Re: any fuses I should check?
thanks but I tested the wiring and it's getting electricity, my conclusion is I have two bad FCVs... yeay me! now if only someone could point me to where I could get them repaired or where I can get a buy one get one free deal?

Author:	Billwill [ Thu Aug 09, 2012 6:30 am ]
Post subject:	Re: any fuses I should check?
maxximr wrote: thanks but I tested the wiring and it's getting electricity, my conclusion is I have two bad FCVs... yeay me! now if only someone could point me to where I could get them repaired or where I can get a buy one get one free deal? How do you know it is getting electricity? From what I can see in the circuit diagram....you will always have +12 volts on one side of the FCV via fuse 16 when ignition is ON. The other side of the FCV is switched to ground by the ECM.....it is actually pulsed PWM I think. So in other words if you are measuring +12 volts on one side with your meter ground lead going to the chassis it does not mean much. On one of your spare FCVs put +12 volts on one side and touch ground briefly to the other side to see if it moves. Edit to add: As papaindigo states....take out the butterfly altogether. The only thing this valve does is give a smoother shutdown.....the 2002 (like mine) to 2004 models have survived quit well without a FCV fitted.

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Author:	maxximr [ Thu Aug 09, 2012 2:53 pm ]
Post subject:	Re: any fuses I should check?
thanks, but I need to sell this one, I have a 2005 I'm keeping, but thanks for the tip!

Author:	maxximr [ Thu Aug 09, 2012 3:17 pm ]
Post subject:	Re: any fuses I should check?
Billwill wrote: maxximr wrote: thanks but I tested the wiring and it's getting electricity, my conclusion is I have two bad FCVs... yeay me! now if only someone could point me to where I could get them repaired or where I can get a buy one get one free deal? How do you know it is getting electricity? From what I can see in the circuit diagram....you will always have +12 volts on one side of the FCV via fuse 16 when ignition is ON. The other side of the FCV is switched to ground by the ECM.....it is actually pulsed PWM I think. So in other words if you are measuring +12 volts on one side with your meter ground lead going to the chassis it does not mean much. On one of your spare FCVs put +12 volts on one side and touch ground briefly to the other side to see if it moves. Edit to add: As papaindigo states....take out the butterfly altogether. The only thing this valve does is give a smoother shutdown.....the 2002 (like mine) to 2004 models have survived quit well without a FCV fitted. As far as testing goes I tried what you said, I'm using one of those light up screwdriver looking things, and I put the ground side on one end and the other point on a different pin, it lights up,but no movement of the gears

Author:	Billwill [ Fri Aug 10, 2012 7:57 am ]
Post subject:	Re: any fuses I should check?
The only way you can really test the voltage going to the FCV is by means of an an oscilloscope to scope the PWM pulses on the negative leg of the unit.

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