Hi everyone. New to the forum. I have a 2005 f-350 with the 6.0 diesel. I've noticed rough starts in the morning when extremely cold. No smoke just lots of shaking. Plugging into the block heater helps. I am getting a code of u0407 and the glow plug light on the dash does

Not illuminate. I can not hear the glow plugs either when turning the key forward. Suggestions for a fix?

 

I'd check fuses first, just because, but code is for invalid data from glow plug control module. It's likely bad. Passenger side valve cover near alternator. Silver finned small box with 1 black and 1 green connector.

Injectors cam be individually tested with a meter at those plugs using this diagram. Each injector should measure between .1 and 2.0 ohms.

Under hood wiring diagram
https://www.ford-trucks.com/ford-man...%20diagram.pdf

If you want to check for power try this. (Thanks Bismic)

Install an inductive ammeter on one bank at one of the two harnesses at the Glow Plug Controller Module (GPCM). You can get up to 200 A at first, but then should stabilize around 35-45 A. Check the other bank with the inductive ammeter. Both sides should read the same. If not, check the amps to each individual glow plug to determine which one (or ones) is bad. Each glow plug should draw 10-12 Amps.

Fuseable link for glow plugs about 4"" down the harness from where it connects to pass side battery. take the tape off. should be going under your a/c line.

All this information comes from the 2006 Service Manual.

Glow plug on time is dependent on oil temperature and altitude. The GPCM will
command the glow plugs on for 1 to 120 seconds. The GPCM does not operate
if the oil temperature is above 55C (131F)
It looks like the GPCM is really 2 units in one box.
Glow plug to ground 0.1~2 Ohms
Glow plug connector to GPCM connector Less that 5 Ohms

Pin #3 on both is the VBattery

Green connector
pin #1 is gp#5
pin #2 is gp#7
pin #6 is gp#1
pin #7 is gp#3
pin 8 goes to the PCM
pin 9 goes to the PCM

Black connector
pin #1 is gp#6
pin #2 is gp#8
pin #6 is gp#2
pin #7 is gp#4
pin 9 goes to the VPwr

The Glow Plug length of operation (up to 120 seconds) depends on oil temperature and the BARO reading. Glow plugs are not operated if the oil temperature is above 131 *F (55*C). The Glow Plug system is PCM controlled. The Wait-To-Start light is initiated by the PCM and is independent of the Glow Plug system. Above 131 *F, the PCM will still bulb-check the Wait-To_Start light. The GPM (GlowPlugMonitor) system (part of the OBDII system) is designed to monitor and detect failed glow plugs or failed wiring in the Glow Plug System.

Welcome to FTE

 

Wow! Thank you so much! Great information!