Fuel Level Input (FLI) Circuit Malfunction

DTC P0460 DETECTION CONDITION & POSSIBLE CAUSES

DTC P0460	FUEL LEVEL INPUT (FLI) CIRCUIT MALFUNCTION
DETECTION CONDITION	P0460 indicates a fuel level input (FLI) circuit malfunction due to a low/high FLI circuit input to the powertrain control module (PCM) or a mechanically stuck fuel pump (FP) module.
POSSIBLE CAUSE	Empty fuel tank Fuel pump (FP) module stuck open Incorrectly installed fuel gauge Damaged instrument cluster CASE GND circuit open FLI shorted to VPWR Damaged PCM Overfill fuel tank Fuel pump (FP) module stuck closed Damaged fuel gauge FLI circuit open FLI circuit shorted to CASE GND or PWR GND CASE GND shorted to VPWR
HINT	FLI Description Indicates the fuel level in the fuel tank. Hard wire signal input to the PCM from the FP module.
Courtesy of MAZDA MOTORS CORP.

DTC P0460 DIAGNOSTIC PROCEDURE

DTC P0460		FUEL LEVEL INPUT (FLI) CIRCUIT MALFUNCTION
STEP	INSPECTION		ACTION
1	Was the PCM quick test performed?	Yes	Go to next step.
1	Was the PCM quick test performed?	No	Perform PCM quick test. See PCM QUICK TEST .
2	DTC P0460: CHECK FUEL TANK LEVEL Key on, engine off (KOEO). Observe and record fuel gauge reading. Access FLI PID using scan tool. Are both the fuel gauge and the FLI PID indicating between slightly above one quarter (30% on FLI PID) and three quarters (70% on the FLI PID) filled?	Yes	Go to step 4.
2		No	Key OFF. Inspect fuel tank for leaks. Repair fuel tank if necessary. Check for a damaged fuse for the fuel pump (FP) to fuel gauge circuit. For a damaged fuse without a DTC P0460: Check for CASE GND short to VPWR circuit. For fuel gauge inoperative without a DTC P0460: See PINPOINT TEST 1: NO COMMUNICATION WITH THE INSTRUMENT CLUSTER . For DTC P0460: Go to next step.
3	CHECK FOR INADEQUATE FUEL LEVEL Key on, engine off (KOEO). Observe both the fuel gauge and FLI PID while performing the following: If fuel level is under one third (33% on FLI PID), add 2 to 3 gallons (7.57 to 11.36 liters) of fuel to the fuel tank If fuel level is over three quarters (75% on FLI PID), drain 2 to 3 gallons (7.57 to 11.36 liters) of fuel from the fuel tank Does either the fuel gauge or FLI PID indicate a movement upward or downward as the fuel was either added or taken away?	Yes	Drive vehicle and rerun PCM quick test. If DTC P0460 is still present, Go to next step.
3		No	Key OFF. Go to step 5.
4	CHECK FLI CIRCUIT VOLTAGE Key on, engine running (KOER). Access FLI V PID using scan tool. Is voltage or FLI V PID reading between 1.23 and 2.25 V?	Yes	For DTC P0460, fault is intermittent. See GENERAL PINPOINT TEST 4: INTERMITTENT . If here from symptom troubleshooting, replace fuel gauge. Go to step 12.
4		No	Go to next step.
5	CHECK FUEL PUMP MODULE RESISTANCE Key OFF. Disconnect fuel pump (FP) module. Measure resistance between FLI and CASE GND pins on the FP module (at pigtail). Is resistance between 15 and 160 ohms?	Yes	Go to next step.
5		No	Check for stuck fuel level float on fuel pump (FP) module. Repair as necessary. If free movement is present, replace the fuel pump module. See FUEL PUMP REMOVAL / INSTALLATION . Go to step 12.
6	CHECK FLI CIRCUIT VOLTAGE AT FUEL PUMP Disconnect the instrument cluster connector (0922-102) to the fuel gauge. Key on, engine off (KOEO). Measure voltage between FLI circuit at the fuel pump harness connector and battery negative post. Key OFF. Is voltage greater than 5 V?	Yes	Go to next step.
6		No	Go to step 8.
7	CHECK FLI CIRCUIT FOR SHORT TO VPWR IN HARNESS Disconnect PCM. Key on, engine off (KOEO). Measure voltage between FLI at the fuel pump harness connector and battery negative post. Key OFF. Is voltage greater than 10.5 V?	Yes	Repair short circuit. Go to step 12.
7		No	Replace PCM. See POWERTRAIN CONTROL MODULE (PCM) REMOVAL / INSTALLATION . Go to step 12.
8	CHECK FLI CIRCUIT FOR SHORT TO PWR GND IN HARNESS Key OFF. Disconnect PCM. Install breakout box, leave PCM disconnected. Measure resistance between PCM test pin 12 (FLI) and battery negative post. Is resistance greater than 10K ohms?	Yes	Go to next step.
8		No	Repair short circuit. Go to step 12.
9	CHECK FLI CIRCUIT FOR SHORT TO CASE GND IN HARNESS Measure resistance between FLI and CASE GND circuits at the fuel pump (FP) module. Is resistance greater than 10K ohms?	Yes	Go to next step.
9		No	Repair short between FLI and CASE GND. Go to step 12.
10	CHECK FLI CIRCUIT FOR OPEN IN HARNESS If here from Symptom Troubleshooting, measure resistance of FLI circuit between PCM test pin 12 and fuel pump (pigtail) harness connector. Measure resistance of FLI circuit between PCM test pin 12 and pin 12 of 0922-102 at the instrument cluster. Is each resistance less than 10.0 ohms?	Yes	Go to next step.
10		No	Repair open circuit. Go to step 12.
11	CHECK CASE GND CIRCUIT FOR OPEN IN HARNESS Measure resistance of CASE GND between FP module connector and battery. Is the resistance less than 10.0 ohms?	Yes	Replace fuel gauge or repair as necessary if here from Symptom Troubleshooting. See INSTRUMENT CLUSTER . Then Rerun quick test. If DTC P0460 is still present, replace PCM. See POWERTRAIN CONTROL MODULE (PCM) REMOVAL / INSTALLATION .
11		No	Repair open circuit. Go to next step.
12	VERIFY TROUBLESHOOTING OF DTCs COMPLETED Connect all disconnected connectors. Clear DTCs from PCM memory using WDS or equivalent tester. Perform PCM quick test. Is same DTC present?	Yes	Replace PCM. See POWERTRAIN CONTROL MODULE (PCM) REMOVAL / INSTALLATION . Repeat PCM quick test.
12		No	If any other DTC is present, Go to applicable DTC inspection. See DIAGNOSTIC TROUBLE CODE (DTC) INDEX - POWERTRAIN CONTROL MODULE (PCM) . If no DTC is present, troubleshooting is complete.