I am looking for direction on how to fix and in which priority . I have 4 codes and as you can guess , the check engine light is on . here is what I have :
121 tps pedal position out of range

122 below minimum voltage ? I don't know what is below voltage!

332 egr flow insuffecient

542 fuel pump secondary open / pcm fuel pump ground

I would think I could replace the egr , but How do I go about the others .
Thank you

 

Several things:

A problem with the TPS sensor. Most likely, a bad sensor or a bad wire to it's connectors.

EGR system problem. Most likely either either a faulty DPFE sensor or a clogged EGR port/tube. EGR valve rarely fail.

As for the 542, that code is commonly set when you have an engine stall. I'd ignore it unless you have a symptom that specifically points to an electrical fault inthe fuel pump circuit.

Steve

 

Codes do NOT mean to replace anything - they only tell you what circuits are not returning their expected signals. And those definitions aren't accurate, anyway. Look them up on one of these, and post the definitions:

http://www.troublecodes.net/Ford/
http://www.broncodata.com/tech/codes.htm

The first step is ALWAYS to confirm that the indicated condition actually exists. Is the TPS actually returning an out-of-range signal? If not (if the signal is IN-range), replacing it certainly won't eliminate the code.

.

It might even be that someone tampered with the throttle stop screw, but you have to check the TPS voltage against that chart to even have an idea.

Most EGR faults on these engines are triggered by vacuum leaks, so start there. Common locations include the green (EGR) line & the vacuum reservoir on the R wheelwell.

The FP code suggests the key was on at some time when the inertia switch had tripped.

I'd clear the codes and see which ones come back. This thread explains how to properly check, clear, & interpret codes.

 

Thanks guys for the help !

I tired to clear all codes from the directions on the links given here . I am down to a 122 which is going back to TPs below minimum voltage . I know the screw has not been moved as I have not touched it and there is what appers to be factory sealant still on it .
I attempted to test the voltage to tps as the link provided by Steve was showing , but I'm guessing I've done it wrong because the voltage is way off from what the chart shows .
Key on - engine off I got 11.4 volts
engine running I got 11.2 volts .

I poked the leads through the wire insulation on the two wires ging to the tps .

White wire with black srtipe - black lead on meter
red wire - red lead

What am I doing wrong trying to test this ?
The truck seems to to idle high in my mind , but like mentioned above I have not touched any adjustments .

Thank you for your help .

 

Those color codes and voltages tell me you weren't measuring the at TPS.

The TPS has three pins. One is signal return (ground), one is Vref (+5V), the other is the signal out which should vary from about 1.0 Vdc to almost +5 Vdc as the throttle plate is opened.

Steve

 

I am getting 4.83 at idle , it does not change at all as the throttle is opened .
Thank you

 

Are you certain you're not measuring the Vref line? If you are on the correct line, you have an open ground, an open sensor, or a testing measurement error.

If that, in fact, was the correct line, you should be getting a DIFFERENT fault code (over voltage, not under voltage).

Don't take this personally, but I'm leaning toward a testing error....

Steve

 

Would it be possible to have no voltage ?

black lead on gray wire with red stripe
red lead on gray wire with white stripe

I stripped just enough insulation to insure good contact , but nothing even through throttle opening .

There is also a brown wire with white stripe , this is the wire That I got the 4.83 the first time .

Thanks for sticking with me !

 

Here's the electrical diagram for your system for download: 1995 5_8 Engine Controls.pdf

Refer to page 25-4. The Vref line is GRAY/RED and should be between 4.5 and 5.5 Vdc, the BROWN/WHITE is SIGNAL RETURN (ground), and the GRAY/WHITE line is the signal out that should vary with the movement of the throttle.

Connect your common (black) meter lead to the battery negative terminal and leave it there while making all your measurements.

Steve

 

Thanks Steve ,

I measured as you said above -
common to negative post - red to gray with white wire .43 at idle , as i opened up the throttle it started climbing up to .55 .

Since I already had stripped a spot on the vref , gray with red wire I measured it the same way . .44 up .55 as throttle opened. Not sure if that is relavant or not ?

In my previous posts when I came up with the 4.83 I had the tps unhooked and took the voltage off the male pins coming from the wiring loom , not with the two connected . sorry for dragging this on and thanks again .

 

If those readings are accurate (sounds like it) then the TPS sensor has a low resistance to ground (leaky, but not quite shorted..)

To double check, measure the Vref line as you disconnect the TPS connector. If it pops from the 0.5 volt value back up to near 5 volts, then replace the TPS.

FWIW, I've never seen such a failure mode in a TPS firsthand, but I suppose it's possible... In every case of Vref shorted to ground I've seen, the PCM was disabled and the engine would not run until the Vref short-to-ground was repaired.

Steve

 

The TPS is tested ONLY by backprobing while it's installed & connected normally, KOEO. Did you read the caption of the graph I posted?

 

I believe after reading back through and loking at the chart I have finally done this correctly , still getting the voltages in my last post . Is there a gasket between the throttle body and intake plenum or do I just need the sensor and unbolt the throttle body ?
I thank both of you for talking me through this deal . My ol' truck is only managing around 11 mpg , so as you can see I need help it a little !

 

Thanks both of you for your help !! fixed, light is out new tps did the trick . Hopefully this helps the mileage a bit , now on to the front fuel pump problem as soon as save some more pennies .

Thanks again.