Feedback voltage from tps into o2 sensor?

outlander · Jan 7, 2019

Renix 4.0
I was out in the garage messing around with my engine scanner and noticed something strange.
With engine off key on i was watching the tps signal while i was pushing the gas pedal.
At the same time i had the o2 circuit pulled up on split screen and noticed that when i pushed the gas the o2 feed would go up a few 10ths of a volt....
Weird right?
Is this something normal or should i start digging into the harness and see if ive got a short between the two circuits?

Tim_MN · Jan 7, 2019

What kinda vehicle are you working on ?

outlander · Jan 7, 2019

89 xj 4.0

outlander · Jan 7, 2019

Where are the resident renix experts?
Cruiser....590....ect.

8Mud · Jan 7, 2019

Might be back feed from the ground circuit. Ohm your TPS ground to battery negative.

lawsoncl · Jan 8, 2019

8Mud said:
Might be back feed from the ground circuit. Ohm your TPS ground to battery negative.

That's my guess as well. Have a look at the ground to the block where the oil dipstick mounts. I believe all the sensor ground converge there.

http://cruiser54.com/?p=19

cruiser54 · Jan 9, 2019

lawsoncl said:
That's my guess as well. Have a look at the ground to the block where the oil dipstick mounts. I believe all the sensor ground converge there.

http://cruiser54.com/?p=19

That's a good one as is this one. http://cruiser54.com/?p=44

old_man · Jan 9, 2019

I wouldn't be surprised to see this. The voltage amount you are seeing is most likely just normal leakage and the source is a capacitance somewhere in the system.

When you power down, most circuits go into a high Z state. It takes a while for the voltages to bleed off all the way. Even then, things like a keep alive voltage for internal clocks on the radio can leak back through quite unexpected paths. We deal with this frequently in the testing I do on satellites.

This is not the droid you are looking for.

:laugh3:

lawsoncl · Jan 10, 2019

old_man said:
I wouldn't be surprised to see this. The voltage amount you are seeing is most likely just normal leakage and the source is a capacitance somewhere in the system.

When you power down, most circuits go into a high Z state. It takes a while for the voltages to bleed off all the way. Even then, things like a keep alive voltage for internal clocks on the radio can leak back through quite unexpected paths. We deal with this frequently in the testing I do on satellites.

This is not the droid you are looking for.

:laugh3:

"Engine Off, Key on", so sensors are still powered.

Feedback voltage from tps into o2 sensor?

outlander

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Tim_MN

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outlander

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outlander

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8Mud

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lawsoncl

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cruiser54

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old_man

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lawsoncl

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