Data Link Connector (DLC) Malfunction

DTC P1001 OR DTC NOT LISTED DETECTION CONDITION AND POSSIBLE CAUSE

DTC P1001 OR DTC NOT LISTED	DATA LINK CONNECTOR (DLC) MALFUNCTION
DETECTION CONDITION	P1001 indicates any of the following: Unable to access Continuous Memory DTCs. Unable to activate KOEO or KOER Self Test. NGS Tester communication problem. DTC displayed by NGS Tester not listed. KOER Self Test cannot be completed
POSSIBLE CAUSE	Damaged DLC. Incorrect Self Test procedure. VREF is not in specification. Idle RPM out of specification. Open in DLC harness circuit. Short in DLC circuit or associated modules. Damaged PCM power relay circuit. Damaged PCM.
Courtesy of MAZDA MOTORS CORP.

DTC P1001 OR DTC NOT LISTED INSPECTION

STEP	INSPECTION		ACTION
1	Was PCM Quick Test performed?	Yes	Go to next step.
1	Was PCM Quick Test performed?	No	Perform PCM Quick Test.
2	CHECK FOR VREF AT TP SENSOR Key OFF. Disconnect Throttle Position (TP) sensor. Key ON, Engine OFF (KOEO). Measure voltage between VREF and SIG RTN at TP sensor harness connector. Key OFF. Was the voltage between 4.0 and 6.0 V?	Yes	Voltage is within specification. Reconnect TP sensor. Go to next step.
2		No	Voltage is not within specification. Reconnect TP sensor. See TEST 1: VEHICLE REFERENCE VOLTAGE (VREF) .
3	ABILITY TO ACCESS CONTINUOUS MEMORY DTCs Can Continuous Memory DTCs be accessed?	Yes	Go to next step.
3		No	Unable to access Continuous Memory DTCs. Go to step 7.
4	ABILITY TO ACTIVATE KOEO SELF TEST Can KOEO Self Test be activated?	Yes	Go to next step.
4		No	Unable to activate KOEO Self Test. Go to step 6.
5	ABILITY TO ACTIVATE KOER SELF TEST Can KOER Self Test be activated?	Yes	If here for DTC P1001 and other KOER DTCs are present, begin diagnosis with the first KOER DTC that appears. If DTC is not listed in the charts, verify that correct PCM is installed on vehicle.
5		No	Go to next step.
6	RETRIEVE ANY CONTINUOUS MEMORY DTCs NOTE: If failures are present in the following components or systems, the EEC strategy can be prevented from completing the KOER Self Test or cause the PCM to generate a NGS Tester communication error message: Idle speed control. EGR system. Fuel control system. Vehicle speed signal circuits. Mass air flow sensor circuits. Transmission range circuits. Key ON, Engine OFF (KOEO). Retrieve and record Continuous Memory DTCs (MIL and non-MIL). Key OFF. Were any Continuous Memory DTCs present?	Yes	If here for DTC P1001 and other DTCs are present, begin diagnosis with the other DTCs.
6		No	Unable to retrieve any Continuous Memory DTCs. Go to next step.
7	CHECK B+ AT DATA LINK CONNECTOR (DLC) Inspect DLC for damage. Repair as necessary. Measure voltage between B+ at DLC and engine block ground. Was voltage greater than 10.5 V?	Yes	Go to next step.
7		No	Repair open in Data Link Connector B+ circuit. Go to step 16.
8	CHECK DLC CHASSIS GROUND RESISTANCE Measure resistance between chassis ground at DLC and chassis ground. Is resistance less than 5.0 ohms?	Yes	Go to next step.
8		No	Repair open in DLC chassis ground circuit. Go to step 16.
9	CHECK DLC PWR GND CIRCUIT FOR OPEN IN HARNESS Measure resistance between PWR GND at the DLC and battery negative post. Is resistance less than 5.0 ohms?	Yes	Data link passed. Go to next step.
9		No	Repair open circuit. Go to step 16.
10	CHECK BUS+ FOR SHORT TO GROUND IN HARNESS Disconnect PCM. Install Breakout Box, leave PCM disconnected. Measure resistance of BUS+ circuit between PCM test pin 16 and chassis ground. Is resistance greater than 50 ohms?	Yes	Go to next step.
10		No	Repair short circuit. NOTE: Short circuit can exist in harness or associated modules. Refer to MODULE COMMUNICATIONS NETWORK for further diagnosis.
11	CHECK BUS+ CIRCUIT FOR SHORT TO B+ IN HARNESS Key ON, Engine OFF (KOEO). Measure voltage between BUS+ circuit between PCM test pin 16 and chassis ground. Is the voltage greater than 1.0 V?	Yes	Repair short circuit. NOTE: Short circuit can exist in harness or associated modules. Refer to MODULE COMMUNICATIONS NETWORK for further diagnosis.
11		No	Go to next step.
12	CHECK DLC BUS+ CIRCUIT FOR OPEN IN HARNESS Key OFF. Measure resistance of BUS+ circuit between PCM test pin 16 and pin 2 of the DLC connector. Is the resistance greater than 5.0 ohms?	Yes	Go to next step.
12		No	Repair open circuit. Go to step 16.
13	CHECK BUS- FOR SHORT TO GROUND IN HARNESS Key OFF. Measure resistance of BUS- circuit between PCM test pin 15 and chassis ground. Is the resistance greater than 50 ohms?	Yes	Go to next step.
13		No	Repair short circuit. NOTE: Short circuit can exist in harness or associated modules. Refer to MODULE COMMUNICATIONS NETWORK for further diagnosis.
14	CHECK BUS- CIRCUIT FOR SHORT TO B+ IN HARNESS Key ON, Engine OFF (KOEO). Measure voltage between BUS- circuit between PCM test pin 15 and chassis ground. Is the voltage greater than 6.0 V?	Yes	Repair short circuit. NOTE: Short circuit can exist in harness or associated modules. See MODULE COMMUNICATIONS NETWORK for further diagnosis.
14		No	Go to next step.
15	CHECK DLC BUS- CIRCUIT FOR OPEN IN HARNESS Key OFF. Measure resistance of BUS- circuit between PCM test pin 15 and pin 10 of the DLC connector. Is the resistance less than 5.0 ohms?	Yes	Replace PCM. See COMPUTERIZED ENGINE CONTROLS . Go to step 16.
15		No	Repair open circuit. Go to step 16.
16	VERIFY TROUBLESHOOTING OF DTCs COMPLETED Make sure to reconnect all disconnected connectors. Clear DTCs from PCM memory using NGS tester generic OBD-II function. Perform PCM Quick Test. Is same DTC present?	Yes	Replace PCM. See COMPUTERIZED ENGINE CONTROLS . Repeat PCM Quick Test.
16		No	If any other DTC is present, go to applicable DTC inspection. If no DTC is present, troubleshooting complete.