Vehicle Speed Sensor (VSS) Signal Intermittent

DTC P0503, P1500, P1501 DETECTION CONDITION AND POSSIBLE CAUSE

DTC P0503, P1500, P1501	VEHICLE SPEED SENSOR (VSS) SIGNAL INTERMITTENT
DETECTION CONDITION	P0503 indicates poor or noisy VSS performance. P1500 indicates the VSS input signal was intermittent. This DTC is set when a VSS fault interferes with other OBDII tests, such as Catalyst efficiency monitor, EVAP monitor, HO2S monitor, etc. P1501 indicates the VSS input signal is out of Self Test range. If the PCM detects a VSS input signal any time during Self Test (vehicle stopped), a DTC P1501 will be set and the test will abort.
POSSIBLE CAUSE	Noisy VSS input signal from Radio Frequency Interference/Electro-Magnetic Interference (RFI/EMI) external sources such as ignition components or charging circuit (P0503, P1501). Damaged wiring harness or connectors (P0503). Malfunction in module(s) or circuit connected to VSS/TCSS circuit (P0503). Aftermarket add on (P0503). Intermittent VSS connections (P0500). Intermittent open in VSS harness circuit (P1500). Intermittent short in VSS harness circuit (P1500). Damaged VSS or driven gear (P0503, P1500). Damaged PCM (P1500). Damaged TCCS (P0503).
HINT	VSS Description Variable reluctance or Hall-effect sensor. Generates a waveform with a frequency that is proportional to the speed of the vehicle. The lower the speed, the lower the frequency. The higher the speed, the higher the frequency. The PCM uses the frequency signal to control such parameters as fuel injection, ignition control, transmission shift scheduling and torque converter clutch scheduling.
Courtesy of MAZDA MOTORS CORP.
Courtesy of MAZDA MOTORS CORP.

DTC P0503, P1500, P1501 INSPECTION

STEP	INSPECTION		ACTION
1	Was PCM Quick Test performed?	Yes	For P0503: Go to step 2. For DTC P1500: Go to step 5. For DTC P1501: Go to step 6.
1	Was PCM Quick Test performed?	No	Perform PCM Quick Test.
2	DTC P0503: INSPECT VSS AND CIRCUIT FOR AN INTERMITTENT Check for harness intermittents by verifying the pins are properly seated in connector shell, wiring is properly crimped, no corrosion exists in the harness and sensor is securely mounted. Are there any indications of harness intermittents?	Yes	Repair as necessary. Go to step 7.
2		No	Go to next step.
3	CHECK PCM VSS PID FOR INPUT SIGNAL Access the VSS PID with NGS Tester. Drive the vehicle at several steady state speeds above and below 50 km/h (30 mph). NOTE: For NGS Testers which have Data Record feature, record data for playback to help identify variations. During each steady state speed observe the VSS PID for variations of (+) or (-) 8 km (5 mph) for greater than 10 seconds. Is there any indication of a noisy or intermittent signal with the VSS PID?	Yes	Go to next step.
3		No	Unable to duplicate or identify fault at this time. Repair any other DTCs.
4	CHECK RESISTANCE OF VSS SIG HARNESS Disconnect PCM and VSS sensor harness connector. Install Breakout Box, leave PCM disconnected. Measure resistance of VSS SIG (VSS+) circuit between PCM test pin 58 and VSS sensor harness connector. Is the resistance less than 5.0 ohms?	Yes	Unable to duplicate or identify fault at this time. See TEST 4: INTERMITTENT .
4		No	Repair high resistance. Go to step 7.
5	DTC P1500: VISUAL INSPECTION Visually inspect the VSS SIG (VSS+) circuit harness. Did the visual inspection reveal potential failure?	Yes	Repair fault as necessary. Go to step 7.
5		No	Unable to duplicate or identify fault at this time. See TEST 4: INTERMITTENT .
6	KOER DTC P1501: CHECK PCM VSS PID FOR INPUT SIGNAL Start the engine and idle in NEUTRAL. Access the VSS PID with NGS Tester and observe for vehicle speed input to the PCM. Increase the engine speed, not greater than 2000 rpm, several times while observing the VSS PID. Is the reading on the VSS PID less than 5 km/h (3 mph)?	Yes	Unable to duplicate or identify fault at this time. If DTC P1501 still exists, refer to DRIVE CYCLES .
6		No	Go to step 4.
7	DRIVE CYCLE Make sure to reconnect all disconnected connectors. Clear DTCs from PCM memory using NGS tester generic OBD-II function. Perform OBD II Drive Cycle. See DRIVE CYCLES . Retrieve pending code. Is same DTC present?	Yes	Replace PCM. See COMPUTERIZED ENGINE CONTROLS . Go to next step.
7		No	Go to next step.
8	VERIFY REPAIR Perform PCM Quick Test. Is any DTC present?	Yes	Go to applicable DTC inspection.
8	VERIFY REPAIR Perform PCM Quick Test. Is any DTC present?	No	Troubleshooting complete.