DTC P0620 generator control circuit malfunction

Anybody know where I should start checking with this code?

Should I clear it and see if it comes back?

 

clearing is where I always start. Strokertech is the resident powerstroke guy, but I'll see if i can help!
Have you had any charging issues or no start problems?
do you have a dual generator/alternator setup?

Looks like the Upper circuit or circuit one which would be the upper alternator! I would start with checking connections and go from there. If that leads to nothing, One of us will get you the exact diagnosis on it!

Whoops forgot one more thing! Check the fuse-able links on the Alternator Wiring!

hope this helps!

 

Does your truck have dual alts?

 

Yes I have dual alternators and have not had and charging trouble that i'm aware of yet. I know that my livewire will go down to 10 or 11 volts when the glow plugs are on but as soon as they turn off it's right back to 13.5 to 14.0 all the time. I still have the original batteries in this truck and both show green in the sight glass, I know there about due to be changed if I don't wanna get stuck with a dead battery one day. As far as starting issues i do occasionally have issues on the first start of the day. Usually if it don't start after 8 to 15 seconds of cranking on the first try I know to cycle the key again and she'll fire right off. This issue is intermittent and has done this since day one and the dealer told me they can't duplicate it so they can't fix it, that was when i first got it new in 03. It comes and goes it might do it every day for a week and then 6 months later it'll do it once and not again for a while.

Tomorrow I will clear the DTC's and see if it comes back. If it does i'll move onto checking the wiring and fusible links. I did have alot of work done on the truck in december so maybe the shop that it did caused a problem, I had the heads replaced due to streched head bolts and now have studs with fire ringed heads.

Thanks for your help I'll post back with my findings.

 

I'm glad to hear you have dual alts, I'll tell you why. 9 out of 10 superduties and econolines I have ever worked on with dual alts have had that code. Never have seen a charging issue and cant explain the code but have seen it a hundred times.

 

OK, I'll clear it for the hell of it tomorrow anyways. Do you have any idea on what the starting issue I explained above could be? Bad GPR maybe?

Thanks

 

All I know is 8-15 seconds is a LONG time! Make sure you are alowing your glow plugs to cycle the first time you spin it. If there is a high pressure oil concern it should kick a low icp code. If there are no codes for the oil system its gonna come down to someone being able to duplicate it.

 

Yeah that 8 to 15 is long I usually know pretty quick if it's not gonna fire and just recycle the key after a few seconds of initial cranking. I overrated those times. I always wait for the start light to go out and give it a little longer after it's out before cranking.

Here is my current DTC list

p0403
p0405 both EGR related due to the EGR being unplugged and using an EGR delete up pipe

p0603 Internal control module keep alive memory (KAM) Error ??????????????

p0620 one of the 9 out of 10 with this code

p1000 testing not complete

p0000 ???????

 

We have a Code look up here

https://www.dieselbombers.com/codes.php

 

Well, if your egr is unplugged it is normal for those codes, 603 will be there if you have a chip, 620 is the normal dual alt code and the 1000 is normal.