[Farmer_Jack_13]

Howdy, I have a 2002 F250 SD 7.3 Auto with the wonderful no throttle response issue. It started as the fuse #45 OD wire issue which I have fixed, then the Accellerator Position Sensor went out. I switched out the pedal assy with a NAPA unit and all was well for about a month then no throttle.
I replaced the pedal assy under warranty from NAPA and still nothing. I checked the fuse #45 and its is good.
Can anyone tell me what the voltages should be on the pins so I can test this with a volt meter? I would assume the 3 pins that make up the tps part would be a constant 5V, a ground, and one that varies based on pedal position but don’t know which is what.
Also, is there a way to check the IVS?
I had NAPA pull another pedal assy from the warehouse just in case, but what are the odds that the new assy I just got was bad? I would prefer to test it somehow before exchanging it again.
Any help yall can provide would be appreciated.
Broc

 

[klhansen]

Welcome to TheDieselStop :smile2:

The way to test the accelerator pedal position sensor is with an ohmmeter. It's a potentiometer with 5 v applied on the two outside terminals (highest resistance no matter what the position of the pedal) and a wiper terminal that changes resistance as you move the pedal.
The IVS is a simple switch that should change state (open to closed or closed to open - can't recall which right now) as the pedal position comes off idle. If it doesn't change state when you start to press the go pedal, the PCM ignores the signal from the pedal position sensor and the engine stays at idle. Most likely you have an issue with the IVS circuit, either it's not getting power (I think 12V, but not absolutely sure) or the IVS is not switching. It's also possible the sensing wire to the PCM from the IVS is open.

 

[Farmer_Jack_13]

OK, got home tonight and picked up the new pedal assay. They couldn't get another doorman for days but got a Ford motor company reboxed one. This one has 10 pins like the original
i put this on and still no throttle. This one checks 12v for the ivs that switches with the pedal the tps has 5v on the outer pin with the 3rd pin switching from .5v to 4v with the pedal. The 2nd Pin reads .45 millivolt and dosent change.
I just for kicks i checked the father in laws 1995 F350 sitting here that works and on that the outer is 12v, the center switches from .5v to 4v and the upper reads mV
and dosren t change.
This is the 3rd switch in this. What else can this be? Pcm? Where is the pcm even on this?

 

[klhansen]

It might be the PCM, but I doubt it. More than likely a wiring issue. Have you checked for frayed/shorted wires? Any damage or evidence that someone has fooled around with the harnesses (adding a wire tap, etc.) would be suspect.

The PCM is located up under the dash to the left of the parking brake pedal. To remove it, you have to disconnect the rectangular (vertically oriented) harness connector on the engine side of the firewall, then remove the bracket bolts up behind the parking brake pedal.

But before you try that, I'd get a PSD capable scan tool (beg, borrow or buy one) that can display parameters. AutoEnginuity software that runs on a laptop is a good choice. With that, you can confirm that the PCM is at least receiving the signals you measured with your voltmeter. Those sound correct to me (the one's I've messed with didn't get over about 4V corresponding to mashing the pedal to the floor).

 

[Farmer_Jack_13]

Ok, Now I am really confused

Ok, I humored the Father in Law and disconnected the batteries to reboot the computer and it worked!!! now the new pedal assembly works like a charm!!!


The trouble is I didn't fix any problems, so now I feel like I am sitting on a ticking time bomb. What should I be checking to eliminate this before it leaves me stranded somewhere? I started tracing wires but need to dig deeper as the pedal wires went up behind the dash and out of sight so I don't know if they have been monkeyed with. The bundle coming from the wheel, like the ignition switch is on an older chevy has been spliced into which I need to correct, but these aren't rubbing anything to cause the issue with my pedal.


Help, Any Ideas? Can the PCM be taken in and checked to ensure there isn't a problem there? Would a problem in it show up when it isn't acting up? Why cant they keep engines simple without all this computer crap?


Thanks fer any assistance yall can provide.

 

[ArcticDriver]

Dug up this old thread on the "Throttle Position Sensor" although my symptoms are different

I think I may have a "flat spot" or "dead spot" in my pedal travel. Its just enough to cause a "stumble" and brief drop in RPM but as soon as I depress the pedal beyond that then there is no further issue. I can give it WOT without a hiccup so I am leaning against fuel pressure issue.

Can I test the wiper sensor and the Variable Speed Sensor KLH described above using an AE scanner?

No codes coming up and no CEL.

I never read about these TPS giving any problems for us 7.3 PSD trucks.

Thanks

 

[79jasper]

Same as any other drive by wire setup.
You can use a dvom to do a read out.
Some have just hosed them down with electrical cleaner.

Sent from my SAMSUNG-SM-G935A using Tapatalk

 

[ArcticDriver]

Same as any other drive by wire setup.
You can use a dvom to do a read out.
Some have just hosed them down with electrical cleaner.

Sent from my SAMSUNG-SM-G935A using Tapatalk

AE has two parameters:

1. Voltage
2. Throttle Position

I could not find a dead spot using this method. It is possible to do the test with KOEO.

I took the (3) bolts out and removed the entire pedal assembly and cleaned it as you suggested and now its time to take it out for a test run.

Thanks for your help.

 

[79jasper]

Only other thing that comes to mind would be a cps problem.

Sent from my SAMSUNG-SM-G935A using Tapatalk

 

[Graupp]

ArcticDriver;
The way to test it, is to take it out on the highway and put it on cruise control, and then
accelerate using button control on the steering wheel..
Cruise control simply over rides the pedal [TPS]...
Simple as that and you'll know..
[That's what happened to mine]

 

[ArcticDriver]

ArcticDriver;
The way to test it, is to take it out on the highway and put it on cruise control, and then
accelerate using button control on the steering wheel..
Cruise control simply over rides the pedal [TPS]...
Simple as that and you'll know..
[That's what happened to mine]

This sounds like some great advice.

So a dead spot will still occur if its in CC ? Thats perfect since I can increase in specific 1-mph increments.

Thanks very much. Tomorrow morning I will put it to the test. I am in the mountains west of Denver on I-70. Right near Eisenhower Tunnel.

 

[Graupp]

This sounds like some great advice.

So a dead spot will still occur if its in CC ?

>> NNOOOO !!! <<<

It WON'T occur because the CC ""OVERRIDES "" the TPS

It's the TPS that has the flat spot ..:lol::look around:
=============

OK; Since you've got a 2000, I "THINK" this is the part you'll need

Motorcraft Pt # F4SZ-9B989-AA
You can buy t on the internet for less than $50
Takes about 10 minutes to install...have fun..

 

[ArcticDriver]

>> NNOOOO !!! <<<

It WON'T occur because the CC ""OVERRIDES "" the TPS

It's the TPS that has the flat spot ..:lol::look around:
=============

OK; Since you've got a 2000, I "THINK" this is the part you'll need

Motorcraft Pt # F4SZ-9B989-AA
You can buy t on the internet for less than $50
Takes about 10 minutes to install...have fun..

OK...now I understand what you meant :grin2:

The dead spot is getting worse quickly.

Thanks !

 

[ArcticDriver]

I do wonder why AE does not report a voltage drop or irregularity at the flat spot ?

 

[Craig9409]

I had this issue develop on my truck usually doing it a couple time a day while using the accelerator pedal. Never on cruise control. I replaced my pedal assembly which cost $98.00. I got the pedal online from Rock Auto. The unit in the truck was a sealed unit so it can not be serviced. The replacement cured my problem. I didn't see any reason to try to trouble shoot the pedal since it can't be repaired. I also sprayed the plug down with Electromotive contact cleaner and lubed the contacts with dielectric grease. The truck doesn't stumble to idle anymore. I have test driven it about 150 miles in stop and go traffic. I have a 2001 F-250, AT, 7.3. The truck never did this before, I only have 77,000 miles on it. I've owned it 4 years and on a recent cross country trip, it developed this problem about 5 days down the road. I discussed it in a previous thread titled 7.3 drops to idle underway. I replaced the CPS thinking at first that would solve it. It didn't. So I then suspected the pedal and its internal IVS and TPS sensors. My truck set no codes and no idiot lights came on.

 

[ArcticDriver]

Craig,
I followed your other thread and I am glad You fixed the isssue.
My TPS from Autonation Ford is arriving today ($40/part plus shipping).
I think my 2002 has a newer pedal assembly and since it is an "adjustable" style pedal the cost of a new one is over $500.

 

[Craig9409]

Hi Guys, Well, I have about 350 miles or more on the truck since replacing the accelerator pedal assembly. It seems to be working great now. I have had no episodes since replacing the pedal. I guess a sensor was failing it the old one.