TPS trouble
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TPS trouble
I have a 1992 f150 5.0. Idles high after start up. I checked the tps wires and got 5 volts on the green wire and 11.8ish on the orange wire. The black wire, which I believe is the signal return, only has .02 volts and stays at that regardless of throttle position. I tested the wire harness from the tps plug to the main plug on the inner fender and got .4 ohms so the harness isn’t cut anywhere. I’ve heard the computer going bad causing this. Any ideas and help is greatly appreciated.
Last edited by Wilsalmons; Jul 13, 2023 at 10:08 AM.
Hotshot
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From: Near Salt Lake City
That orange wire should be your VREF (reference voltage that the computer feeds to a few of the sensors) it should have 5 volts max
See if that same wire has the 11 volts at the EVP sensor (VREF should be only 5v everywhere)
That VREF is supplied by the processor, which gets its power through the EEC power relay
I am looking at a 88 thunderbird EVTM for this info, but it should be correct enough
Your green wire is the signal return which should vary the voltage as you hit the gas .8-1.3v low and 4.5-5.0v high
You get that VREF voltage down and your problem will be solved IMO
The injectors get a 12v supply voltage, maybe you have a short somewhere?
See if that same wire has the 11 volts at the EVP sensor (VREF should be only 5v everywhere)
That VREF is supplied by the processor, which gets its power through the EEC power relay
I am looking at a 88 thunderbird EVTM for this info, but it should be correct enough
Your green wire is the signal return which should vary the voltage as you hit the gas .8-1.3v low and 4.5-5.0v high
You get that VREF voltage down and your problem will be solved IMO
The injectors get a 12v supply voltage, maybe you have a short somewhere?
Lead Driver
Joined: Jan 2019
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From: N.W. Alabama
It should idle high after start up, then warm up, and slowly idle its self down. how high is idle after warmed up and driven, some?
This will help -->Throttle Position Sensor Testing, Replacement and Adjustment | Full Size Ford Bronco Forum
This will help -->Throttle Position Sensor Testing, Replacement and Adjustment | Full Size Ford Bronco Forum
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It should idle high after start up, then warm up, and slowly idle its self down. how high is idle after warmed up and driven, some?
This will help -->Throttle Position Sensor Testing, Replacement and Adjustment | Full Size Ford Bronco Forum
This will help -->Throttle Position Sensor Testing, Replacement and Adjustment | Full Size Ford Bronco Forum
Lead Driver
Joined: Jan 2019
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Mine does same thing, they all do, its how they warm up, with the ECM controlling it, like the old carbs with electric chokes, once you blip throttle, idle comes down, winter takes longer, I dont think you have anything to worry about, unless it starts hanging around, you can test/reset your IAC(valve)-->How to Clean and Test your IAC - Ford Bronco Forum
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I did the volt tests again and I told you backwards the first time. My orange wire is at 5.04, green wire is at 11.84,and my black wire is still at .02. I tried with two different tps sensors and got those exact results.
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There is no way for the TPS output signal to be greater than VREF. VREF is the Orange wire, 5.04 VDC is textbook. TPS Output is the Green wire. It can never exceed VREF. Typical output is 0.6 to 5.0 VDC. Signal Return, Black wire, is a dedicated ground back to the computer for several key sensors.
What are you using as the ground reference, the black lead on your meter?
What are you using as the ground reference, the black lead on your meter?
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There is no way for the TPS output signal to be greater than VREF. VREF is the Orange wire, 5.04 VDC is textbook. TPS Output is the Green wire. It can never exceed VREF. Typical output is 0.6 to 5.0 VDC. Signal Return, Black wire, is a dedicated ground back to the computer for several key sensors.
What are you using as the ground reference, the black lead on your meter?
What are you using as the ground reference, the black lead on your meter?
Last edited by Wilsalmons; Jul 13, 2023 at 10:34 AM.
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battery negative terminal. I’m following a guide from another forum. https://www.f150forum.com/f10/testing-tps-290537/ If his information is wrong let me know.
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Last edited by Wilsalmons; Jul 13, 2023 at 11:21 AM.
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