Ford F150 Pickup. Manual - part 1577

Fig. 355: Identifying Data Link Connector (DLC) Circuits & Connector Terminals (Focus 2.3L, LS & 
Thunderbird) 
Courtesy of FORD MOTOR CO. 

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline

  

Fig. 356: Identifying Data Link Connector (DLC) Circuits & Connector Terminals (All Others) 
Courtesy of FORD MOTOR CO. 

Testing 

1) For KOER Only DTC P1001: Verify Self-Test Procedure 
This Non-MIL code will be set when Key On Engine Running (KOER) Self-Test does not complete in 
the time intended. 

This test addresses the following:  

z

KOEO or KOER self-test is unable to be activated.  

z

Unable to access Continuous Memory DTCs.  

z

Scan tool communication concern.  

z

DTC displayed by scan tool not listed.  

z

Power Take Off (PTO), if equipped.  

z

DTC P1001 KOER Self-Test cannot be completed.  

Possible causes are:  

NOTE:

For additional testing information, see DIAGNOSTIC AIDS.

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline

  

z

Damaged DLC.  

z

Incorrect self-test procedure.  

z

VREF is not within specification.  

z

Idle RPM out of specification.  

z

Open in DLC harness circuit.  

z

Short in DLC harness circuit or associated modules.  

z

Damaged PCM power relay circuit.  

z

Damaged PCM.  

z

PTO circuit, if equipped.  

Ensure scan tool connector and DLC, located under dash panel, are not damaged or defective. Ensure 
scan tool is correctly attached to DLC. If equipped, ensure PTO switch/actuator is in OFF position. Verify 
correct procedure was used to activate Continuous Memory, KOEO or KOER self-test. If proper self-test 
procedure was performed, go to next step. If proper self-test was not performed, refer to procedures under 
QUICK TEST. 

2) Vehicle Type 
 
For 2003 model year, the LS and Thunderbird are equipped with an Electronic Throttle Control (ETC) 
system and a High Speed - Controller Area Network (HS-CAN) communication protocol. If the vehicle is 
an LS or Thunderbird, go to step 30). If the vehicle is not an LS or Thunderbird, go to next step. 

3) Check VREF Voltage To Throttle Position Sensor 
Turn ignition switch to OFF position. Disconnect Throttle Position (TP) sensor. Turn ignition switch to 
ON position. Using a DVOM, measure voltage between TP harness connector SIG RTN and VREF 
circuit terminals. See Fig. 163-Fig. 166 . If voltage is 4-6 volts, voltage is within specification. Go to next 
step. If voltage is not 4-6 volts, voltage is not within specification. Reconnect TP sensor and go to TEST 
C, step 1). 

4) Check Link Communication With TP Sensor Disconnected 
 
Ensure TP sensor is disconnected. Connect scan tool to DLC. Turn ignition switch to ON position. Using 
scan tool, access TP V PID from PID/DATA MONITOR & RECORD menu. If TP V PID is not 
accessible, go directly to next step. If TP V PID is accessible, reconnect TP sensor while observing TP V 
PID. If scan tool communication error occurs only when TP sensor is reconnected, VREF circuit is 
shorted to SIG RTN circuit in TP sensor. Replace TP sensor. If no scan tool communication error occurs, 
go to next step. 

5) Ability To Activate KOEO Self-Test 
 
If KOEO self-test can be activated, go to next step. If KOEO self-test cannot be activated, go to step 7). 

NOTE:

Loss of VREF caused by an open, or short to PWR or GND, can cause an 
SCP communication error, or an unable to complete self-test concern.

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline

  

6) Ability To Activate KOER Self-Test 
 
If KOER self-test cannot be activated or completed, go to next step. If KOER self-test can be activated 
and you were directed here to diagnose DTC P1001 and other KOER DTCs are present, go to 
DIAGNOSTIC TROUBLE CODE DEFINITIONS and service DTCs in order retrieved. If DTC 
retrieved is not listed in DIAGNOSTIC TROUBLE CODE DEFINITIONS, obtain PCM part number and 
ensure correct PCM is installed for application. Also, check Technical Service Bulletins (TSBs) or 
manufacturer for PCM changes or calibration (Flash Vehicle Identification Block) updates. 

7) Retrieve Any Continuous Memory DTCs 
Perform CONTINUOUS MEMORY SELF-TEST under QUICK TEST. If any Continuous Memory 
DTCs are present, service DTCs as necessary before continuing. See DIAGNOSTIC TROUBLE CODE 
DEFINITIONS. If unable to retrieve any Continuous Memory DTCs, go to step 31) (Focus 2.3L) or go 
to next step (all others). 

8) Check B+ Voltage To Data Link Connector 
 
Disconnect scan tool from DLC. Inspect DLC for damage and repair as necessary. Using a DVOM, 
measure voltage between chassis ground and DLC terminal No. 16 (B+). See Fig. 355 or Fig. 356 . If 
voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, repair open in DLC B+ 
circuit. 

9) Check DLC CHASSIS GROUND Circuit For Open In Harness 
 
Turn ignition switch to OFF position. Using a DVOM, measure resistance between negative battery 
terminal and DLC terminal No. 4 (CHASSIS GND). If resistance is less than 5 ohms, go to next step. If 
resistance is 5 ohms or more, repair open in CHASSIS GND circuit to DLC. 

10) Check DLC PWR GND Circuit For Open In Harness 
 
Ensure ignition switch is turned to OFF position. Using a DVOM, measure resistance between negative 
battery terminal and DLC terminal No. 5 (PWR GND). If resistance is less than 5 ohms, go to next step. 
If resistance is 5 ohms or more, repair open in PWR GND circuit to DLC. 

11) Perform Data Link Diagnostic Network Test 
 
Connect scan tool to DLC. Turn ignition switch to ON position. If scan tool does not have DATA LINK 
DIAGNOSTIC NETWORK TEST capability, go directly to step 22). Using scan tool, perform DATA 
LINK DIAGNOSTICS. If either PCM: NO RESPONSE/NOT EQUIPPED, PCM: NO RESPONSE CKT 
914BUS (+) or PCM: NO RESPONSE CKT 915BUS (-) message is displayed, go to next step. If 
specified messages are not displayed, no concern is indicated at this time. Repeat QUICK TEST. 

NOTE:

Faults in idle speed control, EGR system, fuel control system, electronic 
secondary air system, Vehicle Speed Sensor (VSS) circuits, Mass Airflow 
(MAF) sensor circuits or Transmission Range (TR) sensor circuits can 
cause self-test to be incomplete or scan tool to display communication 
error message.

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline