Hey guys, i'm new to owning a diesel. One week Friday. I have read until blurry eyed on what to do with this. I bought this truck from my father and he told me their were some things wrong with it but wasn't sure exactly what. Its losing power at all speeds but its not a significant loss of power. I can be accelerating or coasting and it will drop 3 to 4 miles per hour randomly then pick right back up. sometimes it will do it 3 or 4 times in a row, sometimes only once. I did the key trick and got a p-1693 code and that's it. i thought they should do two p-done's but i only got one. Also he says the vp has already been replaced along with the lift pump. I did the apps reset and it hasn't solved my problem. Where do i go from here? Some threads I have seen say ecm or vp? what else is there? don't have money for two many repairs. He has no aftermarket gauges in either Did I jump into something I can't handle?

P.S. literally knew nothing about diesels a week ago

 

May be the APPS. Set the cruise at 60 and see if it still does the random speed thing. If it stops, you need to replace the APPS....

 

Cruise went out about a year ago he didn't say how long this has been going on either

 

first check/clean every ground and make sure they are clean! but that seem like a bad apps, if the apps is bad a reset wont fix it

 

Alright thanks ill check the grounds and replace the apps and see what happens. I'll keep ya updated on how its doing.

 

Cleaned all the grounds and went to autozone and got a diagnostic and got no codes yet when I turn the key three times still getting p1693? Still no apps

 

APPS wont always set a code ,I have replaced a bunch of them and most of the time there was no code, also by chance have you checked fuel pressure @ the vp? and hows the filter?also factory lift pumps are garbage seen them last 6 months

 

Lift pump and vp were replaced 30,000 miles ago. Maybe a year? I haven't checked the pressure at the vp not sure how to do that but I'm learning. I have a friend that can help me out with it once he's back from the oil field. Trying DIY right now. Filter is good replaced a three weeks ago. Thing that might put a twist is this had been going on for about three years but my dad never bothered to fix it.

 

Fuel pressure and electrical issues..... Check both. Find out what the fuel pressure is doing while driving and check both batteries and all major electrical connections and grounds. If you can, use a scan tool too see if you can pull another code since the 1693 is a companion code.

 

Can Autozone scan both the ECM and the PCM? If they only scanned the PCM, then the 1693 indicates a code residing in the ECM.

 

on my 01 the "key trick" gives ecm AND pcm codes, is that not true of all years?

 

No, 98.5-99 requires a scanner, key trick does not work.

On edit, swear OP said it was a 99, but now can't find it.

So I had better remain silent for now............

 

Went to autozone and they couldn't get any codes at all. I just got the 1693 when I do the "key trick" but I ordered the apps Sunday from timbo. Autozone said they scan both with it.

 

I only got one p-done message on my 01 I don't know if that's a problem or that's what that year should do.

 

p-done means that the scan is done running through the process. And a scanner would pick up all codes too. The 1693 is a companion code and doesnt necessarily mean there's another code but its always a good idea to look if you're having trouble trying to diagnose an issue. Generally the companion code is letting you know that there is a communication issue somewhere with the ECM and the FPCM. Ya have to love the electronic age.