[wyatt022298]

Has anyone else ever had anything similar happen? I've just started having this issue where I'll have intermittent dead pedal issues at 55 mph, give or take a few miles an hour. I drop down to 45 or speed up to 65, and it drives perfectly fine. Usually when it happens, if I lift my foot off the pedal and then get back on, it'll respond again. Also doesn't seem to happen when I'm giving it enough to actually accelerate, it only happens when I've got the pedal down just enough to maintain my speed.

While I haven't actually got the truck scanned, the only code I've had on the odo readout was a p0500, which has since gone away. The APPS was replaced with a timbo APPS roughly 6 months ago. No signs of any issues with the VP44, it's always been fed good pressure. No white smoke, truck always starts good, it'll rev up to 3200 RPM under load no problem.

Only thing that I've noticed is that on the data logging part of my iquad, sometimes it'll readout speeds that aren't possible. I kept it running tonight on an hour long drive and it said that my max speed was 169 mph. That's obviously not possible for these trucks with an NV4500 and 3.54s. It also appears that the vehicle speed jumps around some in my data log, it'll go from a constant 60 to 80+ mph and then back down to what the actual speed is. Could this be related to my dead pedal issue?

I hate to start another dead pedal thread, but the only condition that constantly causes it is vehicle speed, and I spent several hours researching and found almost no information on anything similar.

 

[wyatt022298]

Anyone have any ideas? I drove my truck 25 minutes each way to work and back today and had 0 issues until I decided to try to cruise around 55. As soon as I take it up above 60 or under 50, it just stops acting up.

 

[NCC74656]

when i had this issue it was due to a poor connection on the VP44, harness had two wires about 15" down line that were chafed on the retention clip and shorting

 

[wyatt022298]

when i had this issue it was due to a poor connection on the VP44, harness had two wires about 15" down line that were chafed on the retention clip and shorting

Thanks for the idea, I'll make sure I check that. I'd love for it to be something that simple.

 

[NCC74656]

simple, yea... took me a week to test all the wiring and find where hte issue was, at first i started with the apps sensor

 

[bigfish95971]

You can test the apps by tapping the #3 pin/wire and monitoring it with a voltmeter when driving. On cruise or steady foot throttle on flat ground it should read about 1.2 volts roughly but hold fairly steady. If it drops to about .5 volts with dead pedal and then jumps when you add throttle you have a bad spot in the apps rheostat and apps is bad. Other issues that can cause dead pedal if that checks out OK are loose or dirty battery terminals and cables, bad VP or ECM, and AC from the alternator damaging those parts. Regardless clean and check all battery terminals, cables and ends and for AC v at alternator with a good voltmeter with a 2v scale AC..

 

[wyatt022298]

I figured it out what's happening but I need some help with figuring out what is causing it. I was watching the data logging on my adrenaline and noticed that the speed readout on it will jump up to anywhere from like 130-170 mph and that's when I get the dead pedal issues. It also very rarely reads out the actual speed I'm driving, usually well over how fast I'm actually driving. My speedometer however reads accurately.

Anyone ever have this issue? I'm thinking about replacing the sensor on top of the rear diff and checking very thoroughly for chafed wires or anything that could be shorting out. If neither of those are the problem, I'm guessing it's the PCM/ECM, is there any good way to check for this?

 

[wyatt022298]

Forgot to mention that my cruise control doesn't seem to be working either, if that helps narrow it down any.

 

[NCC74656]

spedo is pulled from rear diff housing, maybe sensor back there is bad? although if teh comptuers are seeing a different speed idk if they pull from multiple sensors or not

 

[wyatt022298]

spedo is pulled from rear diff housing, maybe sensor back there is bad? although if teh comptuers are seeing a different speed idk if they pull from multiple sensors or not

That's the biggest thing confusing me right now. I just thought that the computers gave the readout to my speedometer. The speedometer is working fine. My quadzilla's data logging is showing that the computer intermittently sees like 150+ mph speeds, which is when I have the dead pedal issues. Unless it's possible for the sensor to give the right speed readout to the speedo while giving the wrong reading to the computer.

 

[ArNy32]

That's the biggest thing confusing me right now. I just thought that the computers gave the readout to my speedometer. The speedometer is working fine. My quadzilla's data logging is showing that the computer intermittently sees like 150+ mph speeds, which is when I have the dead pedal issues. Unless it's possible for the sensor to give the right speed readout to the speedo while giving the wrong reading to the computer.

Have you taken then adrenaline out of line,could get some weird results with aftermarket devices.

 

[wyatt022298]

That's the biggest thing confusing me right now. I just thought that the computers gave the readout to my speedometer. The speedometer is working fine. My quadzilla's data logging is showing that the computer intermittently sees like 150+ mph speeds, which is when I have the dead pedal issues. Unless it's possible for the sensor to give the right speed readout to the speedo while giving the wrong reading to the computer.

Have you taken then adrenaline out of line,could get some weird results with aftermarket devices.

I haven't yet. I'm thinking I will after work.

I've also noticed that it seems to do it more at night after its started cooling off or after its rained. Maybe just a coincidence but could it be moisture getting somewhere it shouldn't be and causing funny readings? Not too sure though, I just drove to work at 5 am with no issues and the truck had plenty of dew on it. Had the adrenaline going and it was reading my actual speed so I don't know what to think there

 

[wyatt022298]

Also read that speed is actually reported by the ABS computer, anyone ever have like ground or connection issues with it?

 

[wyatt022298]

So I stopped by autozone and had them use their scanner on the truck and it came back with no codes. Sounds like a wiring/connection issue so I'm going to check over everything in a little bit

 

[CME]

Wondering if you found a fix for this issue? I’m having the exact same issues. ECM? Output speed sensor? Pressure sensor in transmission? Thanks

 

[wyatt022298]

Wondering if you found a fix for this issue? I’m having the exact same issues. ECM? Output speed sensor? Pressure sensor in transmission? Thanks

I'm about 95% sure it ended up being the speed sensor that goes in top of the rear axle. The speedometer worked fine, but if I pulled up the app for my Adrenaline, it would show the speed bouncing around like crazy and it would sometimes bounce up to reading like 200 mph, which would cause it to defuel until it went back to reading kind of normal.

If you do replace it, maybe try not to use an autozone part, I've already had to replace it again. Also be careful removing the old one, mine was actually physically falling apart and I ended up having to pull the diff cover due to that.

 

[bigfish95971]

I did not reread all psots. Did you clean all battery terminals to perfect shiny metal to metal connection.