Throttle Position Sensor Testing
Thread Starter
|
Junior User
Joined: Jan 2005
Posts: 58
Likes: 0
Throttle Position Sensor Testing
I am trying to find what is wrong with my '89 F250.
Is there a way to test the TPS without the prescribed "breakout box" ?
There must be a way to check resistance or voltage variations while operating the throttle. Reference voltage stays right at 5v.
It doesn't start up easily and I get random and inconsistent codes, the latest one is 63. I am still thinking it may be the computer, but no one stocks matching part numbers (someone previously posted that it came out of a Bronco not a pickup)
Is there a way to test the TPS without the prescribed "breakout box" ?
There must be a way to check resistance or voltage variations while operating the throttle. Reference voltage stays right at 5v.It doesn't start up easily and I get random and inconsistent codes, the latest one is 63. I am still thinking it may be the computer, but no one stocks matching part numbers (someone previously posted that it came out of a Bronco not a pickup)
Posting Guru
Joined: Jul 2009
Posts: 1,069
Likes: 1
From: Toledo, Ohio
TPS's are a pontentiometer. They only get around 5 volts current max. At 5 volts throttle is at idle (more electrical resistance). It should fluctuate between around 5v and 0v with throttle performance. If its not moving thats probably whats wrong with it. The numbers should get lower as you accelerate (less electrical resistance).
I dont know if this is what you needed but thats how I would base checking it....
I dont know if this is what you needed but thats how I would base checking it....
Fleet Owner
Joined: Aug 2005
Posts: 23,667
Likes: 301
From: Easton,Ks
It is the other way around.
the wire from the TPS to the computer should be 0.90 volts at closed throttle and about 4.5 volts at WOT.
You check it by back probing the plug that goes to it.
The (-) from your analog meter goes to the SIG wire in the same plug. The other wire is 5 VDC. You can not use a DVM for this check only an analog VOM.
For more information go to this link:
Ford Fuel Injection Throttle Position Sensor (TPS)
/
the wire from the TPS to the computer should be 0.90 volts at closed throttle and about 4.5 volts at WOT.
You check it by back probing the plug that goes to it.
The (-) from your analog meter goes to the SIG wire in the same plug. The other wire is 5 VDC. You can not use a DVM for this check only an analog VOM.
For more information go to this link:
Ford Fuel Injection Throttle Position Sensor (TPS)
/
Thread Starter
|
Junior User
Joined: Jan 2005
Posts: 58
Likes: 0
I figured I could hook up an analog meter between two of the contacts and watch for a smooth increase (or decrease) in resistance.
However, thanks for the link! Lots of good info there.
Adjusting the idle screw is something I never would have thought of. The kid who had this truck likely messed with the idle screw on the throttle body as it appears to be mangled on one end.
However, thanks for the link! Lots of good info there.
Adjusting the idle screw is something I never would have thought of. The kid who had this truck likely messed with the idle screw on the throttle body as it appears to be mangled on one end.
Fleet Owner
Joined: Aug 2005
Posts: 23,667
Likes: 301
From: Easton,Ks
When using a DVM you can only check the TPS at each end of the scale and not where the TPS is setting on its sweep most of the time as you drive and where it wares the most.
To use the analog VOM you hook it up and move the throttle real slowly from closed throttle to WOT and then slowly let the throttle close. The needle should move very smooth across the scale from 0.90 volts to about 4.5 volts with no jerks or dead places.
DVM are very good in places but this is not one of them. It is good for checking the 5 VOLT supply and the voltage at each end of the sweep of TPS.
Maybe now you can go back and teach the instructor at the tech school how to do it. But they may not have any VOM still around to use at the school in this way.
Thread Starter
|
Junior User
Joined: Jan 2005
Posts: 58
Likes: 0
Hmmmm. Following the instructions on Ford Fuel Injection Throttle Position Sensor (TPS)
I only got a flat 1V while operating the throttle. Reference voltage was good at 5V, so it seems the TPS is faulty.
Thanks everyone for the info.
I only got a flat 1V while operating the throttle. Reference voltage was good at 5V, so it seems the TPS is faulty.
Thanks everyone for the info.
Thread
Thread Starter
Forum
Replies
Last Post
FORDF250HDXLT
Pre-Power Stroke Diesel (7.3L IDI & 6.9L)
117
Feb 10, 2025 11:29 PM
AZcowboypilot
1987 - 1996 F150 & Larger F-Series Trucks
29
Jul 6, 2019 12:33 AM
WestyNaut92
1987 - 1996 F150 & Larger F-Series Trucks
2
Jan 21, 2017 11:58 PM
AGrayson84
1997 - 2006 Expedition & Navigator
0
Nov 8, 2016 02:56 PM
blueray
1987 - 1996 F150 & Larger F-Series Trucks
24
Apr 13, 2013 07:54 PM
