Table 1. 0274 Atmospheric Pressure Sensor Diagnostic Codes Continued.
TEST OR INSPECTION
Pressure Sensor Voltage
· Always inspect harness connectors that are involved in the circuit. Poor
connections can often be the cause of a problem in an electrical circuit.
Verify that all connections in the circuit are clean and secure and that all
connections are in good condition. If a problem with the connection is
found, correct the problem and verify that this malfunction or diagnostic
code is active before performing this procedure.
· Perform open or short-circuit test at each harness connection to identify
the correct harness to replace.
· Tag all wiring harnesses to aid in installation.
· Perform this test only if condition is active.
DIAGNOSTIC CODE SET CONDITION
Engine ECM Detects Below Normal Voltage on Atmospheric Pressure Sensor
Signal Circuit R747.
· Basic Engine Wring Harness Shorted.
· Fuel Filter Wiring Harness Shorted.
· Engine Interface Wiring Harness Shorted.
· Atmospheric Pressure Sensor.
· Oil Pressure Sensor.
· Fuel Pressure Sensor.
· Intake Air Pressure Sensor.
· Engine ECM.
Test Step 1. Check for Other Active
1. Turn battery disconnect switch and
ignition switch to ON position
2. Connect MSD. Select C15 620
262-4 Five Volt Sensor DC Supply
and check for active diagnostic
Voltage Below Normal Active
code 262-4 Five Volt Sensor DC
Diagnose and repair active code
Supply Voltage Below Normal
Only 274-4 Atmospheric Pressure
Sensor Voltage Below Normal Active
Proceed to Test Step 2.