Testing vapor pressure sensor question

I have a cel - P0450 - Evaporative Emission Control System Pressure Sensor Malfunction

This is the procedure for testing the 5fvze from the '01 manual

Along with the corresponding schematic & there is a R-Y & a LG wire for the sensor connector itself
Engine room #'s E5-17, E2-18
My color wire for E5-17 is R-Y

Then I saw this - It states PTNK, yet uses a different color wire R-G & BR
It has the same engine room # for PTNK E5-17

Am I missing something here? I do not pass the first test procedure, however want to make sure I am covering the bases before I start hunting for a replacement.

 

Your overthinking things again!!

The sensor was your first test and it failed? The sensor is good now your checking the wiring to the ECM did that ring out??

If all the above is good then check the voltage at the ECM the ECM pin outs

 

vc/e2 - 4.9 (at ecm)

Ptnk (r-y)/e2 - 4.9 (at ecm) sensor not connected. I also get this when testing the harness connector itself. Tells me I am getting the correct voltage from the ecm.... My take on it anyway.

Ptnk/e2 - connected, vacuum hose unplugged - 3.2v - this is good
Vacuum applied - it goes up - 4.9v - this is not good. Supposed to go down - .5 or less. Whoops! I didn’t get that part in the first pic.

I am taking it that the sensor is not good. What threw me off was the last pic in which it has a different setup for the PTNK wiring. Same manual.

 

How were you applying Vacuum??

 

Sorry. I got waylaid. I was using a pump. I had cleaned the connector yesterday. Didn't seem bad at all. I tested it again for ha-ha's & now it passes. Seems weird though that the little bit that I picked up with a q-tip would make all that much dif. I can't clear the code to recheck it yet because I sent the TB to Maxbore.

 

PTNK stands for Pressure TaNK..

 

Toyota has some strange translations

 

Your Ptnk /E2- 4.9v is a ghost voltage because it is not connected to anything. Sort of like deadhead voltage. You are correct in that it is a correct reading.

 

Thank you. I like the learning. My confusion still is that PTNK is referred to as R-Y & R-G, yet each are designated as E5-17.

 

The Ptnk/

lol… Welcome to Toyota service manuals… They are notorious for this. They would send out updates to correct mislabeled wiring and components.

 

You kind of have to take them with a grain of salt.

 

You never went by color alone and sometimes you couldn’t trust the pin locations either….

 

Is there a set voltage for the vsv's? I am getting 2.5 for the vsv for vapor pressure & 3 for the vsv for EVAP. I do realize there are resistance tests & checking the valves. Wondering about the voltage itself or is it irrelevant as long as they pass the other tests.

 

Ha-ha! Great!

 

The Ptnk/E2- connected but no vacuum reading is correct at 3.2 volts. That is the “at rest” voltage, since it is atmospheric. However, as you observed, the voltage should have dropped when you applied vacuum. Not gone up. Since it went up (remember open circuit voltage is 4.9) that is a good indicator of a bad sensor.

 

VSV (vacuum switching valves) were normally 12 volts on one side and Toyota would pulse the ground side. Was your multi-meter set up with the red on the positive side of the vsv and the negative on the “trigger” side (pulsed ground)? And was the vsv clicking?

 

I cleaned the connector & retested. It passed, however there wasn't much dirt at all. Making me wonder now that you just taught me the 4.9 was indicative of an open circuit if there's actually something up with the sensor plug itself.

 

Loose pin fit could cause it. What you can do is the male terminal pins in the vapor sensor can be slightly bent to make better contact.

 

I was just checking the next thing down from the VPS. I unplugged it to check the harness for wire color & condition. Decided to check voltage. The 12v was good. Got curious about the ground side & saw it was 2.5. Wondered if this was ok seeing's how the other vsv was 3v. Then I got sidetracked by my neighbor who needed a hand.
So with a pulse ground it would be random?