Vehicle Battery

1994 PCED OBDI-A

SECTION 18A: Diesel Diagnosis — 7.3L DI Engine

A: Vehicle Battery

A1 CHECK BATTERY VOLTAGE CODE 517/518/845

Key on, engine off.
Measure voltage across battery terminals.

Is voltage greater than 10.5 volts?

Note: DTC 517 may be a temporary condition with a 24 volt jump start. DTC 518 may be a temporary condition at crank only.

Yes	No
GO to A2.	SERVICE discharged battery. REFER to Charging/Electrical Group in Service Manual.

A2 CHECK PWR GND CIRCUIT CONTINUITY

Key off.
Disconnect powertrain control module (PCM). Inspect for damaged or pushed-out pins, corrosion, loose wires, etc. Service as necessary.
Install breakout box and connect PCM to breakout box.
Measure resistance between battery negative post and Test Pins 51, 76, 77 and 103 at the breakout box.

Is each resistance less than 5.0 ohms?

Yes	No
GO to A3.	SERVICE open in PWR GND circuit. REMOVE breakout box. RECONNECT PCM. RERUN Scan Tool Diagnostic Test.

A3 CHECK IDM GROUND CONTINUITY

Key off.
Disconnect IDM harness connector.
Measure resistance between battery negative terminal to IDM Pin 26.

Is resistance less than 5 ohms?

Yes	No
GO to A4.	REPAIR open in circuit 570 (BK/W). RERUN Scan Tool Diagnostic Test.

A4 CHECK FOR OPEN BETWEEN SIG RTN AND PWR GND CIRCUITS AT PCM

Key off.
Breakout box installed, PCM connected.
Measure resistance between Test Pin 91 and Test Pins 51, 76, 77 and 103 at the breakout box.

Is each resistance less than 5 ohms?

Yes	No
GO to A5.	REPLACE PCM. REMOVE breakout box. RERUN Scan Tool Diagnostic Test.

A5 CHECK SIG RTN CIRCUIT CONTINUITY

Key off.
Breakout box installed, PCM connected.
Measure resistance between Test Pin 91 at the breakout box and SIG RTN circuit 359 (GY/R) in the Data Link Connector (DLC).

Is resistance less than 5 ohms?

Yes	No
GO to A6.	SERVICE open in SIG RTN circuit. REMOVE breakout box. RECONNECT PCM. RERUN Scan Tool Diagnostic Test.

A6 CHECK SIG RTN CONTINUITY TO IDM

Key off.
Disconnect IDM harness connector.
Breakout box installed, PCM connected.
Measure resistance between Pin 2 at IDM harness connector and Pin 91 at breakout box.

Is resistance less than 5 ohms?

Yes	No
GO to A7.	REPAIR open in circuit 359 (GY/R). RERUN Scan Tool Diagnostic Test.

A7 CHECK KAPWR CIRCUIT AT IDM POWER RELAY

Key off.
Disconnect IDM power relay.
Key on, engine off.
Measure voltage between battery positive at IDM power relay connector and battery negative post.

Is voltage greater than 10.5 volts?

Yes	No
GO to A8.	REPAIR open in circuit 361 (R). RERUN Scan Tool Diagnostic Test.

A8 CHECK KAPWR CIRCUIT VOLTAGE AT EEC POWER RELAY

Key off.
Breakout box installed, PCM connected.
Disconnect EEC power relay.
Key on, engine off.
Measure voltage between battery positive circuit at the EEC power relay connector and battery negative post.

Is voltage greater than 10.5 volts?

Yes	No
GO to A9.	SERVICE open in battery positive circuit between EEC power relay and battery positive post. REMOVE breakout box. RECONNECT all components. RERUN Scan Tool Diagnostic Test.

A9 CHECK IGNITION CIRCUIT VOLTAGE AT EEC POWER RELAY

Note: Vehicles equipped with power distribution (network) boxes have a diode that serves as reverse battery protection for the ignition switch. A continuity check across this diode may be necessary for a No Start/No DTC situation before proceeding with this Pinpoint Test.

Key on, engine off.
Breakout box installed, PCM connected.
EEC power relay disconnected.
Measure voltage between the battery negative post and ignition switch circuit at the EEC power relay connector.

Is voltage greater than 10.5 volts?

Yes	No
GO to A10.	SERVICE open in ignition switch circuits. REMOVE breakout box. RECONNECT all components. RERUN Scan Tool Diagnostic Test.

A10 CHECK DIODE

Key off.
Disconnect diode.

Does diode check OK?

Yes	No
GO to A11.	REPLACE diode. RERUN Scan Tool Diagnostic Test.

A11 CHECK PWR GND CIRCUIT CONTINUITY

Key off.
Breakout box installed, PCM connected.
EEC power relay disconnected.
Measure resistance between PWR GND circuit at the EEC power relay vehicle harness connector and battery negative post.

Is the resistance less than 10 ohms?

Yes	No
GO to A12.	SERVICE open circuit. REMOVE breakout box. RECONNECT all components. RERUN Scan Tool Diagnostic Test.

A12 CHECK VPWR CIRCUIT CONTINUITY

Key off.
Breakout box installed, PCM connected.
EEC power relay disconnected.
Measure resistance between Test Pins 71/97 at the breakout box and the VPWR terminal of the EEC power relay connector.

Is resistance less than 5 ohms?

Yes	No
GO to A13.	SERVICE open in VPWR circuit between the EEC power relay connector and PCM. REMOVE breakout box. RECONNECT all components. RERUN Scan Tool Diagnostic Test.

A13 CHECK VPWR CIRCUIT VOLTAGE

Key off.
Breakout box installed, PCM connected.
Install EEC power relay.
Key on, engine off.
Measure voltage between Test Pin 71/97 and Test Pins 51/76/77/103, 91 at breakout box.

Is voltage greater than 10.5 volts?

Yes	No
SERVICE open or short to ground in VPWR circuit between PCM and EEC power relay. REMOVE breakout box. RECONNECT PCM. GO to A14.	REPLACE EEC power relay. REMOVE breakout box. RECONNECT PCM. RERUN Scan Tool Diagnostic Test.

A14 CHECK IDM POWER CIRCUIT

Key off.
Disconnect IDM harness connector.
Key on.
Measure voltage between IDM Harness Connector Pin 14 and battery negative terminal.

Is voltage greater than 10.5 volts?

Yes	No
Testing complete. RETURN to symptom flow charts. RERUN Scan Tool Diagnostic Test.	CHECK for continuity on Circuit 814 (W/BK). SERVICE as required. GO to A5.