1998 Mercury Grand Marquis 4.6 (P0453- Evap Emiss Pressure sensor High

Looking at the wiring diagram that my friend purchased (haynes manual) this wiring diagram is kinda difficult to identify circuit design.
I'm still trying to locate this sensor, because I'm trying not to bring the gas tank down. So I haven't been able to test at the connector yet. I'm trying to upload the wiring diagram that I'm using. so Noah, Tutti, Tyler what's the best course of action. plus, I don't know whether the pressure sensor is on the tank or in the tank. I'm still trying to research that. thanks.

wrong thread guys. anyone can transfer this info to the repair thread? sorry

I got it. No worries.

At the FTP sensor, grey/red is the sensor ground, red/pink is signal, and brown/white is reference voltage.

The only location description I can find is, "On upper fuel tank assembly." Soooooooo, probably in one of the lines on top of the tank. :silly:

Is there a fuel tank access from the trunk?

Hey mechanic350 i have that waveform book ready for you i sent you a pm a couple days ago asking for your email.

Haven’t checked yet. I will take a look. Thanks buddy

Sorry hardtop here’s my email and thank you sir. moroso321@gmail.com

That’s not the wiring sequence I have Tyler. I’m going to try to upload this picture so you could see what I’m seeing

You've got mail

Thank you hardtop I’m so grateful to you for the information. Thanks again

Hey, at your convenience, can show me a picture of that FTP sensor so that I can make sure that I have the right wiring sequence you mentioned because mine is totally different except the signal wire.

The ftp is in line on the vapor hose on the top of the tank on the passengers side. (Pretty sure passengers side)

I think the wires go through a grommet into the passengers compartment somewhere behind or under the back seat.

For what it's worth, I've never seen one go bad on one of those.
You can monitor FTP on the scanner.
If it's higher than BARO, take the gas cap off and see if it drops. If it does then the vent valve is clogged or stuck closed.

Thanks Noah, the first order of business is for the owner to install the new gas cap and see if that holds the vapors in the tank. secondly, with my Autel 908S Pro I'm going to take a screen shot and share it with you guys so that I can know what is telling me. Thanks again Noah and I will do exactly like you told me.

Tyler, the wires that I have are the following:

Black/Light Blue = ?

Red/Pink = Signal

White/Red = (with the wiper) ? I thought that the wire with the wiper was the signal wire moving back and forth. Correct me if I'm wrong Tyler.

all 3 wires are going to the PCM.