'94 4.o, manual,, code 53

[boosted2.3]

Hello, I'm having a problem concerning the TPS. I've searched but can't find anything. I have a '94 ranger XLT with a 4.0 and a 5 spd. It runs great but has this problem that comes and goes. It just goes full rich and starts running real rough, and sounds like a cammed up engine and smokes black. Before it never lasted long enough to set a code, but this time is set code 53, which is high voltage out of the TPS, or wide open throttle. I replaced the TPS a year ago, but it was for another issue. I tested the TPS and it seems to be working fine. I think it could be a tps wiring problem, but hate to start unwrapping wire. If any of you have had a similar problem, maybe you can save me some time. Thanks

 

[RonD]

Have you tested the TPS wiring with key on engine off?

use a pin(sewing needle) to pierce the wires
Set Volt meter to DC volts, 20vDC if available.

Top wire is 5volts from computer
Center wire is return voltage to the computer, pin 47 on computer
It should read .7-.9volts with throttle closed jiggle wiring harness while testing this wire see if voltage jumps up.
As throttle opens this voltage should climb up to above 4.6v at wide open.
Bottom wire is the ground

View of the computer(EEC) connector and pin numbers here: http://www.auto-diagnostics.info/ford_eec_iv

Pin 26 is the 5volts, it powers several sensors
Pin 47 is TPS return voltage


Wiring diagram here: http://www.therangerstation.com/tech_library/EDiagrams/files/Diagram_Enginecontrols4_0_3_0_3of3.JPG

TPS is in the upper right area
Brown wire is the 5v, pin 26
Grey/red is the ground
Grey/white the the return voltage, pin 47

 

[boosted2.3]

THX Ron for the reply. I'll check these voltages today.

 

[boosted2.3]

I checked the voltages on the TPS, and they seem to be good. I believe I have a wiring problem, but not sure where to start looking. I guess I'm just going to start at the switch and open up the harness till I find something.

 

[boosted2.3]

I just rechecked the tps voltages and the brn/wht wire and the gy/wht wires have the same readings. .92 volts. I've opened and looked at the wire harness and can't find any bare wires at all. I'm lost here. the truck runs, but it is running full rich and will stall below 2.5 k rpm. checking the tps with an ohm meter and it seems to be working properly. help

 

[Spott]

Gy/red should be 0v, measured from ground. If you have .9v here, there's some sort of problem, maybe your ground wire is broken or disconnected.

Gy/wht should be .7-.9v with the throttle closed, and should increase smoothly to almost 5v as the throttle opens.

Brown should be 5v.