Diagnostic Aids
WARNING: This page is about a different car, the 2003 Ford Pickup, 2003 Ford F550 Super Duty, 2003 Ford F450 Super Duty, 2003 Ford Excursion, and 2003 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
After each service or repair procedure has been completed, reconnect all components. Clear DTCs and repeat QUICK TEST procedures to ensure all electronic engine control systems are working properly and DTCs are no longer present.
The Barometric Pressure (BARO) sensor is a cab-mounted variable capacitance sensor used to determine altitude. The BARO signal affects injection timing and fuel quantity to optimize engine operation and control smoke throughout all altitude conditions. The BARO signal is one of the variables used to calculate glow plug ON time. At higher altitudes, glow plug ON time is increased to reduce start-up smoke.
A BARO signal that is detected out of range high or low will cause the Powertrain Control Module (PCM) to ignore the BARO signal and use the Manifold Absolute Pressure (MAP) signal generated at low idle as an indication of barometric pressure.