I just installed the xgauge FICM main voltage. When i first get in the truck and start it, it reads around 35-37 volts, but after a couple minutes of it running it climbs to 47-48.5 and remains there consistently. Do the glowplugs stay on even after the truck is running?? Is this normal?? My truck runs real good, no rough start or smoke at all.

 

Under certain conditions the GP's can stay on after the truck is running. Watch the trucks voltage to see if the FICM and vehicle voltage numbers rise at the same time.

 

okay thanks, can you elaborate on what conditions cause the glowplugs to stay on

 

my ficm voltage may drop during cranking but comes right to 48.5 upon startup

if it starts to run rough you may want to try to solder the joints per thr tech folder
low power is hard on injrctors

 

Quite a few people have posted their FICM voltage readings. I'm wondering how stable they are. Does the gauge show 47 and stay there for a while, then bump up to 47.5 or 48.5 for a while, or does it fluctuate between 47, 47.5, 48 and 48.5 every few seconds. My dealer tech tells me steady, fairly rapid fluctuation within a range is normal. According to him, fluctuations in a range of, say, 45 to 48.5 volts are of no concern.

(This would be after start up.)

What does everybody think?

 

Mine fluctuates very little but it does move some 45.5-47 on the Scangauge. 48-48.5 on a DVOM cranking. It never drops on the SG cranking but the repeat rate on the SG is fairly slow and my truck starts really fast so maybe I'm not seeing a drop?

 

Sarnott, my ficm voltage is at 48 even at startup.
Your voltage seems quite low.
I would suspect a failing ficm, but only after your batteries were charged fully, then load tested.
Also, keep in mind for some reason your truck's alternator does not kick in right away when started. I think it may be a strategy for alternator longevity while the glow plugs are activated.

 

could my ficm be failing even if i have no rough start at all? Also my batteries are 3 months old

 

I just tested my '03 yesterday (I have to use the volt meter method as I don't have a scanner to read). I got 47.7 key on engine off. Couldn't check when cranking as it was just me, then I got 47.8 engine running. It was cold and I started it before the GP light went off hoping to check the voltage while there was the biggest drain. Every other time that I have tested it's been pretty solid at 47.8 when running, don't see fluctuation.

 

I have the same issue reading ficm volts with the Sg. After start up it drops to 43 volts. Once the gp turn off and the changing volt up to 13.8 the ficm will read 47 to 49.

 

Well,
Batteries being what they are, I always suspect them first in these circumstances. Even new ones. (connections as well)
You may also want to check the ficm with a volt meter to verify it's not a Scanguage thing. Also there are a couple of input voltage parameters for the ficm for your Scanguage (vehicle power and logic power) If I remember right, these on mine were 11.5 or so until the engine was running for a bit, then they went to 13.5 to 14. Meanwhile output varied from 47.5 to 49. (11.5v input still made 48v output)
Test and verify. Don't replace good parts, but by all means be proactive and replace a part that may in fact leave you on the side of the road.
Maybe some one else here would know under what conditions a code is triggered ?

 

My SC reads koeo 48.5
koer reads 47.5-48.5

Running it fluctuates between there also. I did see once it bottomed out at 47.0

Problem today is this. The truck was parked for 2 days. Nothing different than any other day. Started this morning like always. The xgauge for FICM was gone! vanished.

So, I need to go re-enter the dang thing.

It worked fine for days. Just weird I think.

 

You have to remember to Save when you're done entering

 

Yeah, I saved. It's been in there for days. Just not today. I've driven it numerous times with it reading FICM. That's how I now how it's been reading.

 

Maybe it's a Scangauge failure. I had my truck flashed and unplugged my Scangauge from the OBD II port for about eight hours. All the XGauges and MPG tank averages and calibrations came back.