Testing throttle position sensor with AE
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Elder User
Joined: May 2004
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Testing throttle position sensor with AE
I’ve been searching quite a bit but can’t find it in my searches. I’m trying to test the throttle position sensor(pedal). I know there are 3 sensors in one. one monitors low to high voltage, one high to low, and one does something else that I’m not sure of. What I’m trying to find out is how to monitor/scan those with my Auto Enginuity? I found throttle position sensor 1, throttle position sensor status, throttle mode, accelerator pedal positions (1,2,3), accelerator pedal percentage, accelerator pedal position status. I thought they(#1,2,3) are all under 5 volts. Which mine are but what should they be? Should two be the same and one opposite? At no throttle- position percentage- 0.00, TPS1- 0.00, throttle mode- 255, #1- 4.04v, #2- 1.54v, #3- 0.93v. Full throttle(not running) position percentage 99.5, TPS1-0.00, throttle mode- 1, #1- 0.56v, #2- 4.12v, #3- 3.59v. The TPS1 is throwing me off because it reads 0v intermittently except when I cycle the key off then back on it reads 12.00v, no throttle, full throttle and running idle or giving it throttle while running. Throttle mode goes form 255 with no throttle, to 0 with slight throttle and then to 1 at 45% throttle. What is the TPS1 sensor?
Fleet Owner
Joined: Nov 2003
Posts: 27,918
Likes: 3,636
APP - Accelerator Pedal Position Sensor (three potentiometers built into the pedal).
A potentiometer is a variable voltage divider that senses the position of a mechanical component. A reference voltage is applied to one end of the potentiometer. Mechanical rotary or linear motion moves the wiper along the resistance material, changing voltage at each point along the resistive material. Voltage is proportional to the amount of mechanical movement.
There are three potentiometers built into the pedal. The service manual refers to them as tracks. Each track is fed +5v and returns a voltage based on the position of the pedal.
APP1 varies from ~4 volts at closed throttle to ~.75 volts at WOT. APP2 varies from ~1.5V to ~4V. APP3 varies from ~1 to ~3.5V. Note that APP1 is inverted from APP2 and 3. If one of the APP signals disagrees with the other two, a code and the CEL is set. If all three APP signals disagree, the PCM defaults to idle.
The only possible way for the APP to fail and cause a WOT throttle condition is for APP1 to fail to .75V, APP2 to fail to 4V and for APP3 to fail to 3.5V ALL at the same time. While this is technically feasible, it is very, very unlikely.
A potentiometer is a variable voltage divider that senses the position of a mechanical component. A reference voltage is applied to one end of the potentiometer. Mechanical rotary or linear motion moves the wiper along the resistance material, changing voltage at each point along the resistive material. Voltage is proportional to the amount of mechanical movement.
There are three potentiometers built into the pedal. The service manual refers to them as tracks. Each track is fed +5v and returns a voltage based on the position of the pedal.
APP1 varies from ~4 volts at closed throttle to ~.75 volts at WOT. APP2 varies from ~1.5V to ~4V. APP3 varies from ~1 to ~3.5V. Note that APP1 is inverted from APP2 and 3. If one of the APP signals disagrees with the other two, a code and the CEL is set. If all three APP signals disagree, the PCM defaults to idle.
The only possible way for the APP to fail and cause a WOT throttle condition is for APP1 to fail to .75V, APP2 to fail to 4V and for APP3 to fail to 3.5V ALL at the same time. While this is technically feasible, it is very, very unlikely.
Fleet Mechanic
Joined: Sep 2006
Posts: 1,491
Likes: 295
From: Fresno, CA
Throttle position is usually referring to the actual throttle on the engine, which you always have on a gas engine. Diesels' don't typically have throttles, but the 03 & 04's did have throttle to help with EGR. It was removed in 05 so you shouldn't have one.
I always find myself correcting new diesel owners when they say they "I put the throttle to the floor"...
I always find myself correcting new diesel owners when they say they "I put the throttle to the floor"...
Tuned
Joined: May 2012
Posts: 332
Likes: 42
Does this mean the 04 actually has a TPS? I am getting some weird issues lately. Cruising and the truck has sudden burst of power, at idle the engine rpm slow down then speed up a little, and when coming to a stop the engine will stay at around 900 rpm before settling down to normal. I am not getting any CEL and will put the scanner on it today. Other than these issues engine rules smooth as can be cranks and runs well.
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Cargo Master
Joined: Nov 2015
Posts: 3,427
Likes: 939
From: Fort Worth, TX
Neither of my 03's had a throttle plate, or even a provision for one. I suppose the previous owners could have replaced the throttle bodies.
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Tuned
Joined: May 2012
Posts: 332
Likes: 42
I had a ford tech run a scan and other than a few spikes in boost everything looked good with no codes. I made a 800+ mile trip this weekend with not a issue. Then yesterday on my way from work it did it again. Few spurts of acceleration and one stop where the idle was slightly elevated then perfect. Mechanic suggested could be turbo getting bad. Could this be a VGT solenoid causing this? Unison ring was replaced about 50,000 miles ago.
Fleet Owner
Joined: Apr 2012
Posts: 27,307
Likes: 549
From: Spanaway
Check the top of the EBP sensor connection and see if you have any exposed wire.
What you are looking for is any short of the Vref 5 volt line. I did not find mine until I
used a 10X magnifier lens. Any short of the Vref and you will have the throttle drop off.
The other places to look are the MAP sensor plug and the throttle wiring harness
down by the throttle. This can be the spot if you have the adjustable peddle set.
What you are looking for is any short of the Vref 5 volt line. I did not find mine until I
used a 10X magnifier lens. Any short of the Vref and you will have the throttle drop off.
The other places to look are the MAP sensor plug and the throttle wiring harness
down by the throttle. This can be the spot if you have the adjustable peddle set.
Tuned
Joined: May 2012
Posts: 332
Likes: 42
Check the top of the EBP sensor connection and see if you have any exposed wire.
What you are looking for is any short of the Vref 5 volt line. I did not find mine until I
used a 10X magnifier lens. Any short of the Vref and you will have the throttle drop off.
The other places to look are the MAP sensor plug and the throttle wiring harness
down by the throttle. This can be the spot if you have the adjustable peddle set.
What you are looking for is any short of the Vref 5 volt line. I did not find mine until I
used a 10X magnifier lens. Any short of the Vref and you will have the throttle drop off.
The other places to look are the MAP sensor plug and the throttle wiring harness
down by the throttle. This can be the spot if you have the adjustable peddle set.
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