Auxiliary Switches

[wp6529]

Originally Posted by Dieselholic

My rpm with the switch on goes to 1200, what i want to accomplish by using the HIC is quicker warmup and battery maintenence, do i have my wrong ? Yeah ND im curious to what the other pass through wires are for, ill send you my e-mail address. Thanks

The Body Builder Advisory Service site that someone posted the links for has all the various TSBs with the info on the SEIC and BCP options among other things.

If your idle goes to 1,200 then you are hooked to the SEIC connection. SEIC lets you control the idle RPM from 1,200 to 2,400 RPM with a resistor or potentiometer, and the default if you don't hook up a resistor is 1,200 RPM.

The BCP mode is a different wire to select, and it is the mode that monitors the battery voltage and adjusts the RPM as needed.

From the 2009 body builders layout book pdf available for download on the BBAS site:

F-250/350/450/550 – Diesel Engine PCM
Circuit Intent Wire Tag Description
-----------------------------------------
INPUT (VPWR)
PTO
PCM Pin C1-30 Circuit No. CE912 Wire Color: Yellow / Green
• Applying vehicle battery voltage to this wire begins SEIC process.
• Signals TorqShift™ transmission to enter SEIC strategy.
• Verifies safety enablers.
• Turns off OBD and other emission-related monitoring.
• Elevates engine speed to target found at PTO-RPM circuit.
• Invokes the PTOC circuit when safety enablers are met.
• Looks for the target engine speed requested at the PTO_RPM circuit using a resistor or
POT.
-----------------------------------------
INPUT (resistor)
PTO_RPM
PCM Pin C1-27 Circuit No. CE914 Wire Color: Green
• Add a resistor or potentiometer to obtain fixed or variable engine target speed.
• Combine in circuit with PTO-VREF and PTO-RTN.
• Speed range available: 1200 rpm to 2400 rpm
-----------------------------------------
INPUT (VPWR)
BCPSW
PCM Pin C1-43 Circuit No. CE926 Wire Color: Purple / Brown
• Applying vehicle battery voltage to this wire begins BCP.
• Engine speed is sent to 900 rpm when all safety enablers are met, regardless of the
degree
of battery charge.
• After 900 rpm, BCP regulates engine speed based upon the degree of battery charge,
up to
2400 rpm maximum.
-----------------------------------------

The yellow/green wire you apparently used enables the SEIC mode and with no resistor connected to the green PTO RPM wire you get the base 1,200 RPM.

The purple/brown wire enables the BCP mode as described above.

Neither option will hurt anything, but they do operate differently.


The pass-through wires are just that, four wires that pass through the firewall from the cab to the engine compartment via the normal wiring harness connectors. They are not connected to anything on either end and are there to provide a convenient way to get wiring from the cab to the engine compartment without having to drill through the firewall. They are documented in one of the TSBs on the BBAS site.

Q162R1.pdf is the bulletin on the BBAS site that explains SEIC, BCP and pass-through.

https://www.fleet.ford.com/truckbbas/topics/qvmp.html

https://www.fleet.ford.com/truckbbas...tml/Q162R1.pdf