Shown below is a 2008 Ford F150 bus network diagram for the DLC connector. When testing NO COMMUNICATION problems, this can help you get the solution. By just using a voltmeter, you can stay away from expensive garages and fix it yourself!
2008 Ford F150 Truck Bus Network Diagram:
This 2008 Ford F150 DLC wiring diagram above is a slight variation of CAN
protocol used on 2005 Ford F150 model. Besides having the standard high speed bus
network, additional low speed bus circuits were added to boost
communication capabilities. The 3 new bus wire MS CAN modules are shown here
on the lower left to handle vehicle entertainment and audio including a
satellite receiver module which is omitted to save space. The 3 UBP single wire
bus modules still appear on the upper middle right and the 2 single wire
bus ISO modules shown on the upper right side. The Instrument panel 3 bus
wire bus modules remain the same including the ABS and PCM modules
sitting next to it.
On the DLC terminal pins, we now have pin 1 for MS CAN+ low speed bus
wire shown in orange wire. Pin 3 is the same UBP low speed bus wire shown
as yellow wire. Pin 6 is CAN Hi or CAN+ high speed bus wire shown in
green wire. Pin 7 is ISO low speed bus wire also shown before as black wire in previous model. Pin 8 is
MS CAN- low speed bus wire shown in brown. Pin 13 stays as a FEPS
programming bus wire shown in blue even in 2005 model. This wire is used solely by Ford or
garages to program scanners. Pin 14 is the CAN Lo or CAN- bus wire shown
in red. Of course we have the usual ground pins 4 and 5 as grounds and pin
16 as the power supply.
Troubleshooting NO COMMUNICATION faults for 2008 Ford F150 bus wires
The procedures for testing the low speed DLC pin bus wires are the same as
in Ford F150 2005 model except minor changes in DLC location and the added pin 8
terminal which is now used. Using the voltmeter, the voltage of a
particular DLC terminal like pin 1, expect a reading of 5 volts at KOEO.
If out of range, disconnect MS CAN+ bus wire red dot connector for DVD
Video module. If voltage remains out of range do the same in the red dot
connector of the Audio module.
To measure the MS CAN- bus wire voltage, probe the DLC terminal pin 8 and
check if you got the 5 volts reading. If not disconnect the blue dot
connectors one at a time from the DVD video and Audio modules.
You can use the same procedure to test DLC terminal pin 3 for UBP and
terminal pin7 for ISO bus wires when disconnecting the red dot
connectors. Note also, if you disconnect the UBP bus wire at the green
dot connector, you isolate all the UBP modules at the same time. However,
if you disconnect it at the brown dot connector, you only isolate both
anti-theft and seat modules. This is how the UBP bus wires are connected
in the actual wiring diagram.
The 2 bus wire high speed modules namely the PCM and Instrument (dash)
panel are also tested the same
as the 2005 F150 model. Using the MINMAX
setting of the voltmeter at KOEO, voltage at pin 6 should fluctuate
between 2.5 v to 3.5 v whereas pin 14 terminal will fluctuate between 1.5
to 2.5 volts. If out of range, pin 6 bus wire can be disconnected at the
blue dot connectors of the Instrument and PCM modules. Pin bus wire at
the yellow dot connectors. This test can apply to the ABS module.
The above bus diagram is for demonstration only.
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