Confused about FICM Voltage

[skanj0]

As the title says, I'm a bit confused about FICM voltage. I understand that FICM voltage should ALWAYS be between 45 and 48 VDC. But, then there's glow plug operation and inductive heating when the engine is cold, which seems to have an effect on FICM voltage. If it didn't, why would Ford advise to disconnect the glow plug control module when testing FICM VDC?

Truck Details:
2006 6.0L. Stock motor except for coolant filter. 64K miles. Mobil 1 5W40 TDT. Re-flashed by Ford in August 2011 to latest calibration. Under factory extended warranty.

Here's what I see on my EDGE CTS:

Cold Start:
Key on/Engine Off - 48 VDC
Key on/Engine Cranking - 45 to 48 VDC
Key on/Engine On - Engine starts at ~40 VDC and then almost instantly drops to the low to mid 30 VDC, and sometimes drops as low as 28 VDC. How far the VDC drops seems to be a function of outside temp and ECT/EOT.

Engine Warm:
When the engine begins to warm I note the FICM VDC begins to increase - almost systematically. When ECT/EOT reaches 100F FICM is usually around 40 VDC; at 150F it then jumps to the 46 to 48 VDC range and remains there.

Engine at Operating Temp:
At Operating Temp (ECT ~195F/EOT ~200F) FICM stays at 47 to 48 VDC.

So, here's the question: Is my FICM operating normally, or is it on it's way out?

[WarChild]

I would say its right on the line.

[1fastTRX]

Drops pretty low, but I've seen that happen from inductive heating. I would say get it reflashed first. I had the same issue with a ficm I had. I repaired the ficm and voltage improved, but still had the issue (dropped to 30s until at operating temp). I swapped the logic side of the ficm with my personal one which did not have that problem. The unit was at 48 volts during all positions. This told me the power supply was not at fault. The logic side was causing the issue due to the flash. Some of the older strategies would ALWAYS kick on no matter what the temps were and slowly improve until at operating temp.

My suggestion would be to get it reflashed sooner than later.

[JasonY]

I've never seen my voltage under 46.5 in any situation. 98% of the time is 47.5 or 48

Jason

[HawaiiBake]

I recently pulled my ficm and did the 58 v upgrade. Read a tone of posts about FICM's and the general rule was if it EVER drops below 48v you should pull it and repair it.

[pl77]

Originally Posted by JasonY

I've never seen my voltage under 46.5 in any situation. 98% of the time is 47.5 or 48

Same here; the only time I've ever seen even 46.5 was when I start it very cold (i.e. < 40F outside temp and it's been sitting all night) and the glowplugs were still cycling at idle. This is when my battery volts are fluctuating between 10.5 and 11.5. Once it warmed up even for 30 seconds it was already between 47.5-48.5. 30 sounds really low for the FICM from what I've read here.

[NYC F-350]

Anything less than 46 volts, under ANY condition, repair the FICM

[skanj0]

Thanks for the info guys. Will need to call the local dealership and make an appointment to get it fixed. When I brought it in over the summer for the same reason, all they did was reflash it (said it was 2 software versions behind) and sent me on my way. Now that it's getting colder the FICM voltage at cold start really seems low.

[jtk27]

Mine was doing the same as yours, pulled it and had it repaired and now 47 is as low as it gets. Obviously with same strategy.

[pl77]

Originally Posted by skanj0

Will need to call the local dealership and make an appointment to get it fixed.

If you can have it off the road for a couple of days, it sounds like ficmrepair.com has gotten some pretty good reviews for their service. Can you borrow a vehicle for a week while they fix the FICM good and proper?