Table 1. 1785 Intake Manifold Pressure Sensor Diagnostic Codes Continued.
TEST OR INSPECTION
1785-04 Intake Manifold
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 Intake Air Pressure Sensor
Signal Circuit R746.
· Basic Engine WIring Harness Shorted.
· Fuel Filter Wiring Harness Shorted.
· Engine Interface Wiring Harness Shorted.
· Intake Air Pressure Sensor.
· Oil Pressure Sensor.
· Fuel Pressure Sensor.
· Atmospheric 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
Pressure Sensor Voltage Below
Normal Active Proceed to Test
Test Step 2. Test for Shorted Intake
Air Pressure Sensor.
1. Turn ignition switch and battery
disconnect switch to OFF position
2. Disconnect connector CM-C7
air pressure sensor connector