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Confused about FICM Voltage
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?
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:
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.
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?
2006 CC SB 4x4 6.0L
BPD 6 Phase 53v FICM, EGR, HD Oil Cooler, Bypass Oil Filter & Water Pump
ARP Studs w/ OEM Gaskets
DC Power 190a upper; DB Electric 200a lower alternator
295/65/20 Toyo MTs
PMF 3 Link
7,500LB Tuff Trucks Leveling Coils
Icon 2.5 piggyback CDC shocks
Dynatrac Free Spin Kit with Dynaloc Hubs
EDGE CTS Monitor w/ EGT, pressure, and temp sensors
Blue FPR Spring Kit
Twin F450 Auxiliary Springs
Banks Monster Exhaust
Truetrac rear/E locker Front with 4.11s