Engine/Transmission (1998.5 - 2002) Truck won't start, code p0122

[JGoss]

My dad has an 01' with a 5 speed that won't start. We put a new VP44 and lift pump on about a month ago from MWFI and the truck ran great until today. He shut it off, got back in to leave and no start. After towing it home he got a 0122. Where should we look first. I've read a lot about the APPS but a lot of that is dead pedal problems. We tried starting it a few times and no go. Maybe we should check the volts somewhere, so if I could get some input that would be great. I can't do any more searching on here because no one can get high speed internet in the boonies. Thanks

 

[Missouri Mule]

P0122= APPS( Accelerator Pedal Position Sensor) signal voltage to low.



I would start at the APPS even though I never read of it keeping a engine from starting.



Did you check codes by key method or scanner?

 

[Doughboy21kd]

Take a digital voltage meter and pierce the wire on the firewall at the 3rd wire harness on pass side of truck closest to the engine. Pin # 23 orange with black tracer(not sure of the wire color). Should read the same as the sticker says on the back of the APPS or close to it.

 

[JGoss]

My plans are to check pin 23, and to take the cables off the battery for awhile, turn the key on, and press the accelerator trick. He was having dead pedal problems before the new vp44, but the codes were for the pump so we figured it was in the electronics for the pump and not the apps. I'm starting to like my common rail more everyday.

 

[daveshoe]

check fuel

Mine had dead pedal and the dead pedal was worse right at start-up. The fuel was dirty or had water in it. Truck started bcause fuel from prior run was in fuel filter and was cleaner,but once the settled out fuel from the tank hit,,dead pedal and death code showed up. Long story,but once the fuel was changed out and new fuel was added,the truck ran/runs great. I wonder how many of these problems are caused by a dirty batch of fuel?

Still have the original VP with fingers crossed. I am not saying that this is the most likely of scenarios,but one that bears checking out. When fuel comes thru the pipeline,Diesel and gasoline travel the same line,separated by a slug of water. With the high fuel prices today,I could understand the motivation of the pipeline distributors to not drain off quite as much water at the gas/diesel changeover

 

[JMetzger]

Does he have a fuel pressure gauge on the truck so that you can see if you have to much or to little fuel pressure?

 

[JGoss]

Well today he did the "reset" to the apps and to my surprise it started!! I borrowed a smarty tonight and checked the codes with it and there are none. so I don't know whats going on now but it runs so we'll see how long that will last. No dead pedal either. By the way he does have a fuel pressure guage and it's fine. Thanks guys.