Need some help...electrical gremlin

[acf6]

Just wondering if you guys have any more knowledge to offer on this problem ive been having. Started the weekend before Christmas, i went to leave my house and my throttle pedal didnt work. Thought it was just a fluke or something, and i restarted it and went out into town and on my way back it died again. Restarted, then as i got up to speed, over about 1500rpm it was surging really bad (see first video) and couldnt go very fast. Restarted truck again, and that went away... So it was sent off to the shop. Got it back last thursday with a new engine harness and EBP sensor. Seemed to run great on the 30 mile drive on the way home, and my mechanic also put 40 miles on it and had no issues. He also couldnt even get it into the shop because the throttle pedal didnt work but i was able to drive it and park it at his shop after the tow truck dropped it off.

http://www.youtube.com/watch?v=xs4XoO4sNI0

Fast forward to monday this week, after it had sat since i picked it up, i was going to drive it to work and went to leave the driveway and had no pedal again. Restarted, made it 100 feet down the street and died again. Restarted, made it 100 feet back in front of the house. After i got home from work i hooked up my auto enginuity to take a drive around, and it only died once, and it didnt seem to be surging again.

Now for codes, this is what im getting

I had the same codes before it went into the shop as well. Now i found another post that i believe is from a ford service manual about testing the throttle pedal based on the codes i had

So i did that test, and my TPS was NOT within those values, so it said replace the TPS which my mechanic already tried with no luck. So i pull up APP 1 2 and 3 along with Vref and i can wiggle the harness and get this...

http://www.youtube.com/watch?v=SozX6-Ci53g

So i told my mechanic what i found and im towing it back up to him tomorrow to replace the harness, but im kind of afraid this isnt going to fix the problem. I find it strange restarting the truck makes the pedal work again, but wiggling the harness cuts the voltage out. If youve made it this far...what do you think? Ive heard a sticking turbo can cause a dead pedal as well...not sure how. Or PCM related. Thanks!

 

[acf6]

Ive read so many threads about what this could be but no one ever seems to have an answer. ICP sensor seems to be pretty common, and ive seen stuck turbo a few times, baro sensor, maf sensor, map sensor...quite a few random things. My truck also has the inferred EBP strategy on it.

 

[Hotrodtractor]

Repeated wiring issues after changing parts and wiring harnesses kind of lead me to believe that you might have an intermittent grounding issue. Granted it could be something else, but all the voltage issues with parts that aren't corrected by changing parts leads me to thing that.

 

[acf6]

I datalogged ICP, IPR, BARO, MAP, MAFv, APP1, APP2, APP3 and vRef for like 30 mins on the way to the shop, which my pedal didnt die once btw, and im not sure if it was an AE fluke or what but it shows 0 for most of the sensors for a few seconds. Weird

but i cant upload the excel sheet because its an invalid file..

 

[acf6]

bump .

 

[POWER-STRUCK]

you might have to test your wiring with an oscilloscope to get the best diag.

 

[acf6]

Just thought I'd update.....been 160 miles trouble free. Fan clutch was the culprit...i guess if it somehow it shorts out the v-ref it can either cause a no-start or idle only operation. Ive had 2 codes for the fan clutch ever since i bought the truck, since it was replaced with an aftermarket clutch when the OEM died and caused the truck not to start. So..if you see this and your pedal doesnt work, try unplugging the fan clutch

 

[MrOneEyedBoh]

Thanks for updating this

 

[acf6]

No problem...i hate coming to threads with no ending so its the least i can do

 

[acf6]

Nevermind, made it about 250 miles before the pedal died twice within 2 miles

 

[acf6]

Anyone have any ideas?? Pedal still dies. Keep in mind, it will die when i go to leave the driveway or just die out on me doing 50mph. Works as soon as you restart it...

 

[acf6]

bump... it also seems to not work at all after the truck sits for a while (week+)

:shrug:

 

[Hotrodtractor]

Anyone have any ideas?? Pedal still dies. Keep in mind, it will die when i go to leave the driveway or just die out on me doing 50mph. Works as soon as you restart it...

Repeated wiring issues after changing parts and wiring harnesses kind of lead me to believe that you might have an intermittent grounding issue. Granted it could be something else, but all the voltage issues with parts that aren't corrected by changing parts leads me to thing that.

I still say intermittent ground issues.

For instance - I had trouble this winter with some low voltage in my Duramax... I was having trouble finding the problem until one night at random the taillights came on in the driveway and drained the batteries. Long story made short a relay corroded inside until the 12 volt positive made contact with the relay point and back fed the computer enough to activate the modules and turned on the truck just like the key was in the ignition. When you tried to use the key to actually start the truck the elevated ground plane didn't provided enough voltage to engage the starter relay and it would just click with fully charged batteries.

 

[acf6]

Yea Im definitely gonna pass grounding issues onto my mechanic. How many grounds are there on this truck? I know offhand theres the 2 under the dash, not sure what those go to

 

[acf6]

Some chaffed wires were found in the steering column going to the tow/haul button i guess...unplugged the tow haul button and he said it seems fine? how would the tow haul button relate to a dead throttle pedal

 

[acf6]

that wasnt it either

 

[acf6]

bump...still at the shop, planning on getting it back this week fixed or not. this is getting ridiculous, its been there 6 weeks and its almost impossible to get a phone call to see whats going on