Diagnostic Aids

NOTE: Barometric Pressure (BARO) sensor is integral to PCM. BARO sensor cannot be serviced separately. PCM replacement is required if a BARO sensor failure is identified.

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.

Perform this test when directed by QUICK TEST. BARO sensor is part of PCM and is not serviced separately. If BARO sensor is faulty, PCM must be replaced. BARO sensor functions are as follows:

Timing Control

The BARO signal affects injection timing and fuel quantity to optimize engine operation and control smoke throughout all altitude conditions.

Glow Plug Control

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.

Detection & Management

A BARO signal that is detected out of range (high or low) by PCM will cause PCM to ignore BARO signal and use Manifold Absolute Pressure (MAP) signal generated at low idle as an indication of barometric pressure.