Fuel Tank Pressure Sensor, code PO453

Hi,

To the best of my knowledge, yes, it should go down. It sounds like the sensor itself may be bad. Take a look through the pic below and confirm the voltages I mention are shown at each pin.

A) Key on engine off: Measure voltage between terminal 3 of the FTPS harness connector and chassis ground. You should have 5v.

B) Key on engine off: Measure voltage between terminal 1 of the FTPS harness connector and chassis ground. You should have 0V.

C) Key off: See pic 2 below for directions for signal ground.

Let me know if that is what you are getting. Note: Pic 1 is the connector pinout.

I will watch for your reply.

Joe

See pics below.

Thanks Joe, I'll get back to you.

You are very welcome. I look forward to hearing what is found.

Take care,

Joe

Okay Joe, i retested the pressure sensor and it passed. I'm still getting the code. Everything in the evap system has been replaced, even the gas cap. I have inspected the hoses the best i can but i see nothing wrong. What am i missing?

Hi,

If everything checks good, there has to be a leak. Since you are not noticing anything that appears to be leaking, at this point you need to smoke test the system.

Basically, smoke is injected into the evap system at a very low pressure. If there is a leak, smoke should exit at that point

You need a smoke machine to do this. I don't know if parts stores have anything like this to rent. You may need to have it done at a shop if you don't have the tool.

If the sensor checks good, the connections between the sensors are accurate, it should work. So, there has to be a leak.

The code itself indicates signal voltage is too high from the FTPS. To me, it sounds electrical, but everything is passing.

Look at the pic below. It indicates the code, what it means, and what are the possible causes.

Let me know your thoughts.

Take care,

Joe

See pic below.

I'm with you, i still think I'm missing something in the wiring. I'll let you know what i find if anything. It's been kind of intermittent. Thanks for your help, sir.

Okay, Joe, i ran the check you gave me and had 0.34 ohms. so, i ran a new wire from the ECM to the pressure sensor and now have 0.00 ohms. The po543 went away. now i have a po449. I replaced the vent valve so I'm assuming it's either another wire issue or the ECM.
Do you have a check i should do for this one?

Hi,

It certainly seems like that is a good possibility.

I attached the diagnostics below for the P0449. It walks you through checking resistance and all checks.

Let me know if this helps or if you have other questions.

Take care,

Joe

See pics below.

Awesome ! Thanks Joe, you have been a ton of help.

Hi,

You are very welcome. I'm glad to know it's helping.

Take care and let me know if you have other questions.

Joe

Okay, Mr. Joe, i have 00.5 ohms at best, what now, replace the wire?

Hi,

That is what I would at least try. It sounds like you may have found it again.

Let me know if that takes care of the issue. I'm interested in knowing.

Joe

Okay, i ran a temporary wire from the ECM connector to the vent valve connector. I'm still reading 00.5 ohms. I did find something though. A few months ago, i replaced the vent valve and the canister. I just ran a hot and a ground from the battery and the valve is not closing. I put another one in it and its holding vacuum and its closing, but it didn't solve the po449. Some of the hoses and clamps have been replaced and there don't seem to be any clogs.
I'm stumped! What next?

Hi,

Did you delete the code, and it came back? I ask because of this. The Canister Closing Valve (CCV) closes off the air inlet into the canister for leak detection of the evap system.

If it wasn't closing, that would set the 449. P0449 is set if pressure is lower than the predetermined threshold which could result from the vent valve being stuck open.

Let me know.

Joe

Yes, i deleted the code several times. It keeps coming back.
This is my (CCV) with it off the car, when i apply vacuum does both ends need to be sealed?

Is this connector under the dash? (See message above also please)

Hi,

Yes, and yes. The connector is a little left of and above the throttle pedal.

Let me know if you are able to locate it.

Joe

Is this it ?

Hi,

How many wires are going to the joint connection? Are they all solid yellow? Interestingly, I found every joint connector on the vehicle except CBGJC4. I am trying to confirm the wiring color in the schematics to make sure you have the correct one. However, I believe you do. However, other J/C's are yellow with an orange tracer, so let me know.

Let me know.

Joe

There are 5 wires all yellow with orange tracer.

Hi,

I went through the entire powertrain management schematic and found no 5-pin connector with yellow/orange wires. Additionally, I can find all junction connectors but not JC4. This has me confused.

Take a look at the schematics below. Note the original was three pages. I had to cut each pic in half to make them readable. I did overlap them. Also, I highlighted every yellow/orange wire I could find.

Take a look and see if that helps in any way.

Take care and let me know.

Joe

See pics below.

Here is a 5 pin with yellow and orange wires. I have a set of wiring diagrams for this car. Hope this will help.

After I looked through the power distribution schematic, that isn't the correct one. There should be an 8-pin connector that controls the CCV. The wires to the connector are all white and it is CBGJC3.

See pic below.

Let me know.

Joe

Okay, there are three connectors next to each other, and i believe there's one with all white wires.
When I'm checking the ohms am i checking the wires or the close valve itself?

Hi,

I would check the wiring. If I recall, you mentioned it was operating when you used a jumper.

Here is a link you likely don't need but may find helpful:

https://www.2carpros.com/articles/how-to-check-wiring

Let me know what you find.

Joe

Okay, Mr. Joe, I got my hands on a bidirectional scanner and the valve is closing through the ECM. I tested the valve for ohms and got 22.2 the first time and 23.6 the second time. I'm confused because when i actuate the valve from the scanner the valve is humming. If i put power and ground from the battery, then it just clicks. So why the humming? Now on another note i noticed if i back probe the valve with a test light, when i actuate the valve from the scanner the test light comes on like it should. But when i turn it off the test light stays on just slightly. So that's a short to ground right? I don't think the short is in the valve itself because if i unplug the harness from the valve the light doesn't go out. I ran a temporary wire from the ECM to the valve, but it didn't change anything. So that tells me the short is not in the ground wire coming from the ECM to the valve. So where should i look? Could it be the positive side that is shorted?

Hi,

If the light is staying on dim, it could be a ground issue that is allowing power to back feed to the light. If you disconnect the PCM, is power lost?

Let me know.

Joe

Yes, i think so but I'll check again tomorrow. What about the humming, is that right ?

Let me know what you find. As far as the humming, can you tell for certain where it is coming from? When actuated, that shouldn't continue powering the valve. It sounds like that is what is happening.

Let me know.

Joe

Yes, it's for sure the valve that's humming.
I think i have tracked it down to a shorted driver because if i bench test the valve it works fine. I ran a temporary wire from the PCM to the valve and it didn't fix anything. When i command the valve on the valve and test light both come on and go out when commanded off,
but the light stays on slightly. It doesn't go out when i turn the key off but if i unplug the PCM it goes out so i'm thinking shorted driver. What do you think of my thinking?

Hi,

It sounds like you may have found the issue. The light shouldn't stay on. Something continues sending power. It could be a short at a connector, so make sure you check when you are disconnecting things.

Let me know how you make out.

Joe

Have verified with the valve commanded off, 12v on the hot side and 3.5 v on the control wire. Bench tested the valve, it works fine. No humming. In the car commanded on it closes but hums. Shorted driver, right?

That is what it sounds like. Something is feeding power constantly to make it hum. Since you indicated a dim light stays on, there must be a short. I went back through thinking there could be a relay sticking but couldn't find anything.

Let me know if you have other questions.

Joe

Thank you, Joe, I'm convinced it's a shorted driver. I have checked the wires and connectors and don't see a problem.

Hi,

You are very welcome. If you have a chance, let me know if that takes care of the problem for you.

Take care,

Joe