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NovaResource -> RE: Input Speed Sensor Replacement ? (4/4/2008 7:49:26 AM)
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[img]http://www.hmaservice.com/files/331/1082062/0140005A.jpg[/img]
DESCRIPTION
This bulletin explains the function of the Vehicle Speed Sensor (VSS) and Right Front Wheel Speed Sensor (RF-WSS) on current Hyundai models and how they relate to Diagnostic Trouble Codes (DTC). It also helps diagnose conditions related to these sensors. KEY information: The same DTC, P0500 (Vehicle Speed Sensor Fault), can be set by the VSS or the RF-WSS, depending on the model. The table on page 6 of this TSB can be used to determine which sensor is pertinent to which model vehicle when working on a DTC for the vehicle speed sensor. VEHICLE SPEED SENSOR (VSS): The VSS on current Hyundai vehicles is one of two types:
1. Electrical sensor (either magnetic or Hall-type sensor) mounted directly on the transmission. This sensor is driven by a gear on the transaxles' final drive assembly. All current model vehicles use this type of sensor, except for the Accent. [image]http://www.hmaservice.com/files/331/1080431/0036011A.jpg[/image] [image]http://www.hmaservice.com/files/331/1080431/0036011B.jpg[/image] 2. Electrical sensor (reed switch type) mounted to the speedometer head unit. This sensor is driven by magnets mounted on the speedometer shaft, which is driven by the speedometer cable. [image]http://www.hmaservice.com/files/331/1080431/0036011C.jpg[/image] The main functions of the VSS are to:
1. Send a signal to the speedometer -- input to the speedometer (except for vehicles equipped with a speedometer cable and reed switch VSS).
2. Send a signal to the ECM/TCM (this signal is typically used by the ECM/TCM for diagnostic purposes).
RIGHT FRONT WHEEL SPEED SENSOR (RF-WSS): Some Hyundai Vehicles incorporate a sensor on the right front hub. This sensor reads a "tone-wheel" mounted on the right front axle assembly. The sensor and tone-wheel function very similarly to the crankshaft position sensor. The main function of this sensor is to send a signal directly to the ECM. [image]http://www.hmaservice.com/files/331/1080431/0036011D.jpg[/image] When driving over a very rough road, the engine will experience a sharply varying load, transferred from the wheels to the crankshaft, which may incorrectly appear to be an engine misfire to the ECM misfire diagnostic logic (based on the analysis of the crankshaft position sensor signal). The RF-WSS is used to minimize inaccurate diagnoses that an engine misfire has occurred. The RF-WSS signal is used to determine if the vehicle is going over a rough road. If the ECM determines that the vehicle is going over a rough road, based on the "roughness" of the signal from the RF-WSS, the misfire diagnostics will be suspended until the driving conditions have changed.
VEHICLES EQUIPPED WITH anti-lock brakes (ABS) or ABS/Traction control System (TCS) WHICH USE the RF-WSS to DETERMINE ROUGH ROAD CONDITION: On vehicles equipped with ABS/(TCS), the RF-WSS sends a signal to the ABS Module (computer). If the vehicle uses the RF-WSS to determine rough road condition (such as the 2001 Elantra), the ABS Module sends a signal to the ECM for use in determining the rough road condition. The RF-WSS and the "tone-wheel" on the right front axle are the same components on ABS and Non-ABS equipped vehicles. A malfunction of the RF-WSS will result in:
1. The ABS light being turned ON.
2. Diagnostic Trouble Code C1203 ("RF Wheel Sensor Open or Short") stored in the ABS Module. APPLICATION: All current Hyundai vehicles are equipped with a VSS, however, not all are equipped with a RF-WSS. Vehicles which are not equippe
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