I've been searching the forum and was trying to find a diagram of that each terminal is for on the diagnostic port in the engine bay?
I know the fuel pump ecu code but would like to know what the rest do.
Like can Check the o2 with a air fuel guage at that port?
If anyone knows please share.

 

Check the FSM under electrical, and then under MFI. I can not link the page for you because you did not mention which one of the trucks you were working on.
FSM link in my signature.
Sorry, did not see the 3vze in title.

 

Anywho...from my 88 3VZ-E...

FP = Fuel Pump
E1 = Engine ground
Ox = Oxygen Sensor
Cco = Catalytic convertor
T = ECU diagnostic Test mode request terminal
E2 = Sensor ground
+B = Battery positive(12V)
VF = Voltage Feedback(see pages 2,13,14 of this pdf)
TEM = A/T oil TEMperature warning computer???
ECT = Electronically Controlled Transmission computer
IG- = Ignitor negative(tachometer signal)


And...no..you can't. But if you want to know what they're supposed to be used for...read the 88 FSM.

 

You can hook a O2 gauge to the Ox (Ox1 on 90-95) terminal.
Dont use a Ohm on the Ox terminal or you can damage the O2 sensor or ECU.

 

O2 gauge? The only one I've ever heard of is a pressure gauge, and I'm sure you're talking about something else.

You can put a voltmeter on the Ox pin to measure the output of the sensor. It should flop between about 0.4 and 0.9 volts, and flop back and forth about 8 times in 10 seconds. This is easy to see on an old-fashioned needle meter, but you need one that will read about 1.5v full scale. With a digital meter the scale is easy, but the update rate may not be fast enough to see the change. So you need a digital meter with an "analog" bar graph.

 

You're supposed to use the VF/VF1 terminal to check the output voltage of the O2 sensor. According to the FSM.

I can't find any references in the FSM(or anywhere else) as to exactly what the Ox/Ox1 terminal is supposed to be used for. Though I won't argue that it can't be used to check the output voltage of the O2 sensor too. Because it can.

So...what's the difference between checking the voltage through the Ox/Ox1 or VF/VF1 terminals?

If you check the voltage via the Ox/Ox1 terminal, that's the voltage signal coming directly from the O2 sensor(before it's received by the ECU).

If you check the voltage via the VF/VF1 terminal, w/ the T/TE1 terminal also ON, that gives you an emulated O2 sensor voltage signal after it's been processed by the ECU. Or, when checking the voltage w/ the T/TE1 terminal OFF, the VF/VF1 voltage then represents the learned value correction.

Specified voltage at Ox/Ox1 only confirms if the sensor is functioning.

Specified voltage at VF/VF1 also confirms that, and that the ECU is functioning too.

 

I've always thought about using an Arduino to set up something similar to the old Toyota diagnostic tools / dataloggers. I just wish I had the time to program it.

 

Ive had O2 (air/fuel) gauges hooked up to the Ox/Ox1 for years, But as I mentioned above dont use a ohm meter on that port.

I do not remember the spacifics of the Vf ports.