Exhaust Back Pressure (EPR) Regulator

1994 PCED OBDI-A

SECTION 18A: Diesel Diagnosis — 7.3L DI Engine

M: Exhaust Back Pressure (EPR) Regulator

Diagnostic Trouble Code (DTC) 514 indicates that a circuit failure has occurred in the EPB control solenoid circuit.

Possible causes:

Is resistance greater than 10,000 ohms?

Yes	No
GO to M2.	SERVICE ground short in Circuit 318 (GY/R). RERUN Scan Tool Diagnostic Test.

Key off.
Disconnect exhaust pressure regulator.
Measure resistance between Test Pin 42 on the breakout box and Circuit 318 GY/R Point B at the EPR harness connector.

Is resistance less than 5 ohms?

Yes	No
GO to M3.	SERVICE open in Circuit 318 (GY/R). RERUN Scan Tool Diagnostic Test.

Key off.
Disconnect exhaust pressure regulator.
Measure resistance between test pins 51/76/77/103 on the breakout box and Circuit 57 BK at Point A of the EPR harness connector.

Is resistance less than 5 ohms?

Yes	No
GO to M4.	SERVICE open in Circuits 57 (BK) and 570 (BK/W) as necessary. (REFER to schematic.) RERUN Scan Tool Diagnostic Test.

Is regulator coil OK?

Yes	No
REPLACE PCM. RERUN Scan Tool Diagnostic Test.	REPLACE exhaust pressure regulator. RERUN Scan Tool Diagnostic Test.

Diagnostic Trouble Code (DTC) 842 indicates:

Are DTC faults present?

Yes	No
SERVICE other (DTC) fault codes. RERUN Scan Tool Diagnostic Test.	CHECK for plugged exhaust or restricted or damaged butterfly valve. SERVICE as necessary.