Idle/Throttle Speed Control Unit: Description and Operation

Models Affected 2008 Model Year F-250/350/450/550 and E-250/350/450.

Purpose

To explain changes and tunctions ot the stationary elevated engine idle speed control system (SEIC) tor power take-off (PtO) and battery charge protect applications, initially introduced by SVE Bulletin Q108 R1 for 2005 Model Year.

Overview

SEIC

- A powertrain control module (PCM) strategy that provides elevated engine speed to drive auxiliary commercial equipment such as hydraulic pumps, generators, air compressors; or maintain vehicle battery charge under extreme electrical demands.
- SEIC is standard in all PCM's tor Super Duty F-Series light truck and E-Series, over-8500 lb. GVWR, with gas or diesel engines and TorqshiftTM automatic or M6 manual transmissions. Is optional tor 4R75E transmissions.

Customer Access Wires for SEIC and VSO/CTO/PARK Signals

- F-Series: Located in cabin, tagged and bundled above parking brake pedal assembly behind data link connector. Pass-thru wires are in the same bundle.
- E-Series: In the engine compartment, tagged and bundled with large harness running below windshield/cowl. Remove some ot the plastic harness tape where the harness exits its plastic support gutter above the engine air induction tube to reveal the blunt-cut wires.
- The final stage manutacturer or up-fifter is required to supply the customer intertace equipment.
- Additional intormation in the Circuit Descriptions section.

Transmission PTO Gear and Port

- Available only on Super Duty F-Series.
- Standard with M6 manual transmission (some PlO installations are prevented by exhaust system interterence).
- Available tor Torqshift 5-speed automatic transmission by ordering "Transmission Power Take-Off Provision". The PTO gear is direct-splined to the torque converter output shatt and thus receives any torque the torque converter is delivering, whether the vehicle is stationary or mobile (i.e. no internal PTO clutch).
- NEVER use any sealer, especially silicone-based, on the PTO port gasket.

Torque and Horsepower

- Torqshift Automatic Transmission: The PTO gear delivers up to 250 tt-lbs torque to the attermarket PTO, and can manage the heat ot 40 hp continuously. Higher horsepower can be delivered, but tor shorter durations depending on the amount ot power required.
- M6 Manual Transmission: The PTO gear delivers up to 250 ft-lbs torque, but has less-capable cooling tor PTO usage than TorqShift.
- Typically, the attermarket PTO cannot use all this available torque and horsepower, so contact the individual attermarket PTO supplier.





Product Descriptions / Special Situations

SEIC

Intended to be commanded ONLY by applying battery voltage to certain customer-access blunt-cut wire circuits, and adding a target-speed resistor, and is only available when the vehicle road speed signal is zero.

- Includes a link circuit which changes trom open-circuit to ground when enablers are met, that may be used to turn on an indicator lamp, while providing battery power to an attermarket PlO clutch or solenoid.
- Ramp rates are tixed and cannot be altered by the customer.
- Maximum engine speed is 2400 rpm.
- Minimum engine speed - Diesel engine: 1200 rpm
- Minimum engine speed - Gas engine: 910 rpm approximately. Gas engine has a 900 rpm stand-by speed that it tirst goes to when SEIC is initiated to step it away trom stall speed that it could dip to as PlO load is applied. This is an unusable speed tor any application. However, a resistor can be chosen that sets the useable target speed tor carrying an auxiliary load to just above 900 rpm. This is mainly intended tor applications using a FEAD-driven PlO device like a clutch-pump, or manual transmission PlO, because the Torq5hittTM torque converter cannot tully lock until 1200 rpm engine speed. WARNING: Using the Torq5hittTM PlO below 1200 rpm risks transmission damage trom over-heating, or attermarket PlO clutch slippage debris.

Typical SEIC Sequence for Torqshift PTO

Initiating SEIC by applying battery voltage to the SE IC-PlO wire immediately commands the PCM to tirst look tor enabling conditions, such as vehicle gearshitt selector in PARK, engine at base idle speed ot about 650 rpm, etc. A complete list ot enablers is provided in the SEIC Enable/Disable Conditions~ section ot this bulletin. Once enablers are satistied then the tollowing takes place:

1. Command is sent to boost hydraulic line pressure in the transmission about 20-30 psi, which is used by the attermarket PTO supplier to hold their PTO clutch.
2. Command is sent to use a unique torque converter lock-up schedule tor stationary PTO.
3. Command is sent to increase engine speed to 1200 rpm detault, or a target speed using a resistor.
4. The low-side driver circuit changes trom open-circuit to ground. It the up-fitter uses the circuit wiring ottered in this bulletin then this will provide battery voltage to the attermarket PTO solenoid to engage the PTO.
5. Engine speed increases to the target, the torque converter locks at 1200 rpm, and hydraulic line pressure increases with engine speed to a maximum ot 150 psi at 1200 rpm.

Special Situations

Mobile PTO Operation (Torqshift Automatic or M6 manual Transmissions)

Always apply battery voltage to the PlO wire to keep SEIC active. Engine speed is no longer commanded by SEIC instead it is controlled by the toot throttle. The increased line pressure and torque converter commands must remain active to protect the automatic transmission. Convert PlO solenoid power to direct-battery instead ot through the SEIC circuit suggested in this bulletin, possibly using the VSO signal circuit. A slightly harsher automatic transmission shitt can be expected but is harmless.

Diesel Engine Regeneration

SEIC strategy takes priority over diesel regeneration strategy in the PCM. Use ot an attermarket throttle-kicker that simulates the toot pedal throttle, or commands through the data-link connector, may not have this protection. Also, it diesel regeneration is commanded, shutting ott SEIC operation tor either PlO or Battery Charge Protection may leave the engine at 1150 rpm, making the operator believe there is something wrong with SEIC. Diesel regeneration may command 700 rpm to 1150 rpm engine speed, and does not require park-brake-set.

Adaptive Cooling

This PCM strategy is new tor 2008 6.4L diesel engine. It automatically restricts engine power when it senses an over-temperature condition, and may interrupt the SEIC-PTO operation. Typically, the over-temperature condition it reacts to will also show up on the temperature gage on the instrument panel. Elevated engine speed, typical ot SEIC operation, may help avoid Adaptive Cooling occurrence due to the resultant additional engine and transmission coolant tlow. However, depending on the auxiliary PTO power being demanded, 1200 rpm may not be enough to prevent the powertrain trom entering Adaptive Cooling mode, but 1500 rpm may.

Alternative Calibration

All new Ford light trucks have an Alternative Calibration or ALT-CAL installed in the PCM that conditions the powertrain during its early litetime. It may increase the PARK-idle or drive-idle speed ot the engine, by as small as 50 rpm or by several hundred. It attects SEIC initiation by not letting it activate, because one ot the SEIC enablers is having a steady, base, idle speed, generally near 650 rpm. It ALT-CAL sets the idle at 700 rpm then SEIC activation will be prevented. ALT-CAL is normally removed atter 50 key-on starts, or by driving over 5 continuous miles; it is also sometimes erased by disconnecting the battery tor a minute or so.

Split-Shaft PTO (Not Recommended)

The Ford powertrain control strategy will not allow tor this operation, whether using SE IC, or an attermarket controller commanding engine speed directly at the toot pedal throttle or through the Ford data-link connector. The PCM will typically react by restricting power and engine speed, and possibly varying speed while searching tor a solution. It may not do this immediately, but atter days or a week ot customer operation. It also will not guarantee a 1:1 transmission ratio command, typically required by split-shatt PTO applications.

Circuit Descriptions for SEIC and Customer Access Signal Circuits

All circuits lead back to pins on the PCM.


















Battery Voltage Sources (VPWR)






SEIC Resistor Charts






SEIC Enable/Disable Conditions






Note-1: A "change-ot-state" at the "PTO-Request" circuit is required to re-invoke SEIC.

When a disabler is seen by the PCM the PTO-Indicator circuit changes trom ground-source to open-circuit. Atter approximately 3 seconds SEIC drops out, returning the engine speed to base idle. For vehicle-stationary operation, the automatic transmission torque converter unlocks as engine speed drops below 1200 rpm. To re-initiate SEIC the operator must turn ott the attermarket PlO switch (removing command voltage to the "PT0-Mode" circuit) and turn it back on again.

Note-2: SEIC is automatically re-activated after approximately 3 seconds atter the disabling condition is removed.

SEIC / PTO - General System Behavior

To guarantee tull advertised torque capability at the automatic transmission PlO gear and through the attermarket PlO clutch, the transmission torque converter must be locked, and the hydraulic line pressure serving the attermarket PlO clutch must be elevated. Applying battery voltage to the PlO circuit is the signal to the transmission to enter SEIC strategy and command these two important tunctions. This applies to both stationary and mobile PlO operations.

If an SEIC disabler occurs:

- GAS engines will require a change-ot-state, meaning the operator is required to turn ott voltage to the PTO-Request circuit, and back on again to re-invoke SEIC and PTO operation.
- DIESEL engines do not require a "change-ot-state" at the "PTO" circuit. Once the disabling condition is removed, the strategy re-invokes SEIC atter approximately 3 seconds, automatically returning the engine speed back to what was commanded by the operator prior to the disabling condition.

Battery Charge Protection (BCP): A diesel-only tunction. When it is switched on the engine speed goes immediately to 1200 rpm, and stays there even it the battery is tully charged. From this state it uses system voltage as well as ambient air temp., engine oil temperature intormation to raise engine speed higher to maintain a certain battery charge. Maximum engine speed in BCP mode is 2400 rpm. The BCPSW circuit may be wired to circuit to Ignition-Hot-in-Run to make it automatic for ambulance. Park-Brake-Set is one ot the enablers ot BCP.

If the Transmission Oil Temperature (TOT) sensor reaches 240°F, then the Torqshift torque converter may disengage, preventing torque trom being delivered to the transmission PTO gear.

SEIC/PTO strategy tunction in the PCM is not attected by the loss ot vehicle battery electrical power.

SEIC Ramp Rate (fixed, not programmable):

- GAS engines: 400 rpm/second.
- DIESEL engines: When tirst applying battery voltage to the PTO circuit the PCM directs the engine to go to the initial target that it sees at the RPM circuit at 200 rpm/second (1200 rpm it there is no resistor in the RPM circuit - open circuit). It resistance is subsequently changed at the RPM circuit then the ramp rate to this second speed target is virtually instantaneous (as tast as the diesel engine can get there).

Correlation between engine speed and resistor values:

- The external voltage source that the attermarket PTO system designer uses to command SEIC through the PTO or PTO-Requesr circuits must be the same as that used by the PCM internally tor predictable SEIC tunction. Reasoning is that a tully-charged vehicle battery tluctuates with ambient temperature.
- The correlation will be better tor diesel engines since the diesel engine SEIC system otters buttered PCM voltage and ground circuits to complete the resistor circuits tor engine speed, while the gas engine system torces the SEIC circuit installer to use chassis voltage and ground.
- It there is a high electrical demand on the chassis battery, such as trom attermarket inverters or generators, etc., the actual elevated idle engine speed may vary with that demand tor any given resistance in the SEIC circuit. More so tor gas engine systems than diesel since gas engine uses chassis battery voltage as a reterence.

GAS Engine Only:

- Normal base engine calibration allows approximately +1-50 rpm tluctuation. It any tactory vehicle accessories are used during SEIC, e.g. a/c, detroster, etc., then that tluctuation may increase to approximately +1-100 rpm or more.
- The sudden loss ot attermarket PTO hydraulic pressure during SEICIPTO operation, like a ruptured hose, may send SEIC engine speed to near 3000 rpm. It is recommended that a hydraulic pressure switch linked to SEIC/PTO be added to disable SEIC/PTO when a hose ruptures.
- Because ot a service brake circuit characteristic at engine-start, invoking SEIC may cause the diagnostic error code FFG_BOO to get tlagged (recorded in the PCM). To avoid this, simply tap the service brake pedal sometime atter engine-start and prior to invoking SEIC. Once the code is set, SEIC may not be available until it is erased.
- Gas engines require a change-ot-state at the PTO-Mode and PTO-Engage circuits whenever a disabler turns off SEIC (remove battery voltage signal and re-apply).
- For attermarket remote engine start-stop: a change-of-state is required to get SEIC to tunction again.