Advisory concerns ramp rate on Ford trucks
Jan 1, 2004 12:00 PM
The National Truck Equipment Association (NTEA) has issued a technical report for members and others using Circuit 322 to obtain stationary elevated idle speed in Ford trucks. Vehicles affected are model year 2003 F-250, -350, -450, and -550 trucks with 6.0-liter diesel engines.
The ramp rate from base engine idle (625 rpm) to the 1200-rpm target is higher than for the prior 7.3-liter diesel engine. This may be too rapid for smooth engagement of transmission-mounted PTO serving high-inertia PTO system start-ups, typical of direct-drive air compressor installations. For final-stage manufacturers completing vehicles with TorqShift automatic transmission and high-inertia start-up type PTO systems, Ford recommends holding completed vehicles for shipment to final customer until the Powertrain Control Module (PCM) can be reflashed with new strategy. The reflash will revert the PCM strategy back to the 7.3-liter ramp rate.
On affected vehicles, the 1200-SEI feature strategy is incompatible for manual transmission vehicles. Do not activate (apply 12 volts to) Circuit 322 (light blue/yellow trace) for manual transmission vehicles. To obtain stationary elevated idle for transmission-mounted PTO or FEAD-mounted clutch pumps, use the Ford Auxiliary Powertrain Control Module (APCM) or equivalent. The PCM reflash noted above will be available to customers with 6.0-liter diesel engine and manual transmission, and will deactivate Circuit 322 and the resultant 1200 SEI feature.
For additional information, phone the Ford Truck Body Builders Advisory Service toll-free at 877-840-4338 or e-mail: bbasqa@ford.com.
