Code P0500 = VSS, I understand the fix BUT I have a question for those who did it.
#1
10-13-2005, 10:25 PM
Code P0500 = VSS, I understand the fix BUT I have a question for those who did it.
I've read all the posts about guys who have had similar problems but am trying to find out which sensor it is.
There are of course 2 speed sensors,, the Tailshaft of the trans and the Rear Differential.
My truck is a 98' Ram 2500 2WD
The ABS, Brake and Check Engine light are on and it pulls the code P0500 which says Vehicle speed sensor.
The transmission shifts fine and the speedo doesnt work till about 45MPH.
Dealer told me to try the one in the rear differential first as that would cause the ABS Lights to come on and cause the same conditions.
But my question is what exactly does the one on the tailshaft do??? I cant see why they would need redundant sensors doing the same thing. So each sensor has to have its own symptons?
2nd question is there individual ABS sensors for the rear wheels or is it just the sensor in the diff housing?
Of course I could easily change both sensor but I dont want to spend the money if I dont have too.
There are of course 2 speed sensors,, the Tailshaft of the trans and the Rear Differential.
My truck is a 98' Ram 2500 2WD
The ABS, Brake and Check Engine light are on and it pulls the code P0500 which says Vehicle speed sensor.
The transmission shifts fine and the speedo doesnt work till about 45MPH.
Dealer told me to try the one in the rear differential first as that would cause the ABS Lights to come on and cause the same conditions.
But my question is what exactly does the one on the tailshaft do??? I cant see why they would need redundant sensors doing the same thing. So each sensor has to have its own symptons?
2nd question is there individual ABS sensors for the rear wheels or is it just the sensor in the diff housing?
Of course I could easily change both sensor but I dont want to spend the money if I dont have too.
#2
10-13-2005, 11:24 PM
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RE: Code P0500 = VSS, I understand the fix BUT I have a question for those who did it.
You might have 2 problems. Before replacing any of the sensors carefully check the wiring connector and harness at each one. They do like to loosen up or corrode. The sensors should be available from a good auto parts store if needed. Also pick up a small tube of dielectric grease to use on the wiring terminals, this will help prevent corrosion.
Vehicle Speed Sensor Operation
PURPOSE
The sensor input is used by the Powertrain Control Module (PCM) to determine vehicle speed and distance traveled.
OPERATION
The speed sensor generates 8 pulses per sensor revolution. These signals, in conjunction with a closed throttle signal from the throttle position sensor (auto. trans. only), indicate a closed throttle deceleration to the PCM. When the vehicle is stopped at idle, a closed throttle signal is received by the PCM (but a speed sensor signal is not received).
Rear Wheel Antilock Brakes
GENERAL INFORMATION
The rear Wheel Speed Sensor (WSS) is mounted in the rear differential housing. The WSS consists of a magnet surrounded by windings from a single strand of wire. The sensor sends a small AC signal to the Controller Antilock Brake (CAB) . This signal is generated by magnetic induction. The magnetic induction is created when a toothed sensor ring (exciter ring or tone wheel) passes the stationary magnetic WSS. The exciter ring is press fitted onto the differential carrier next to the final drive ring gear. When the ring gear is rotated, the exciter ring passes the tip of the WSS. As the exciter ring passes the tip of the WSS, the magnetic lines of force of the sensor are cut, causing the magnetic field to be moved across the sensor's windings. This, in turn causes current to flow through the WSS circuit. Every time a tooth of the exciter ring passes the tip of the WSS, an AC signal is generated. Each AC signal (positive to negative signal or sine-wave) is interpreted by the CAB. It then compares the frequency of the sine-wave to a time value to calculate vehicle speed. The CAB continues to monitor the frequency to determine a deceleration rate that would indicate a possible wheel-locking tendency.
TOOTHED RING AND WSS SIGNAL CHARACTERISTICS
The signal strength of any magnetic induction sensor is directly affected by:
Magnetic field strength; the stronger the magnetic field, the stronger the signal
Number of windings in the sensor; more windings provide a stronger signal
Exciter ring speed; the faster the exciter ring rotates, the stronger the signal will be
Distance between the exciter ring teeth and WSS; the closer the WSS is to the exciter ring, the stronger the signal will be.
The rear WSS is not adjustable. A clearance specification has been established for manufacturing tolerances. If the clearance is not within these specifications, then either the WSS or other components may be damaged. The clearance between the WSS and the exciter ring is 0.005 - 0.050 inch . The assembly plant performs a "Rolls Test" on every vehicle that leaves the assembly plant. One of the test performed is a test of the WSS. To properly test the sensor, the assembly plant connects test equipment to the Data Link Connector (DLC) . This connector is located to the left of the steering column and attached to the lower portion of the instrument panel. The rolls test terminal is spliced to the WSS circuit. The vehicle is then driven on a set of rollers and the WSS output is monitored for proper operation.
In addition to determining distance and vehicle speed, the output from the sensor is used to help control:
Speed control operation
Transmission overdrive operation
Transmission torque converter electrical operation
Vehicle Speed Sensor Operation
PURPOSE
The sensor input is used by the Powertrain Control Module (PCM) to determine vehicle speed and distance traveled.
OPERATION
The speed sensor generates 8 pulses per sensor revolution. These signals, in conjunction with a closed throttle signal from the throttle position sensor (auto. trans. only), indicate a closed throttle deceleration to the PCM. When the vehicle is stopped at idle, a closed throttle signal is received by the PCM (but a speed sensor signal is not received).
Rear Wheel Antilock Brakes
GENERAL INFORMATION
The rear Wheel Speed Sensor (WSS) is mounted in the rear differential housing. The WSS consists of a magnet surrounded by windings from a single strand of wire. The sensor sends a small AC signal to the Controller Antilock Brake (CAB) . This signal is generated by magnetic induction. The magnetic induction is created when a toothed sensor ring (exciter ring or tone wheel) passes the stationary magnetic WSS. The exciter ring is press fitted onto the differential carrier next to the final drive ring gear. When the ring gear is rotated, the exciter ring passes the tip of the WSS. As the exciter ring passes the tip of the WSS, the magnetic lines of force of the sensor are cut, causing the magnetic field to be moved across the sensor's windings. This, in turn causes current to flow through the WSS circuit. Every time a tooth of the exciter ring passes the tip of the WSS, an AC signal is generated. Each AC signal (positive to negative signal or sine-wave) is interpreted by the CAB. It then compares the frequency of the sine-wave to a time value to calculate vehicle speed. The CAB continues to monitor the frequency to determine a deceleration rate that would indicate a possible wheel-locking tendency.
TOOTHED RING AND WSS SIGNAL CHARACTERISTICS
The signal strength of any magnetic induction sensor is directly affected by:
Magnetic field strength; the stronger the magnetic field, the stronger the signal
Number of windings in the sensor; more windings provide a stronger signal
Exciter ring speed; the faster the exciter ring rotates, the stronger the signal will be
Distance between the exciter ring teeth and WSS; the closer the WSS is to the exciter ring, the stronger the signal will be.
The rear WSS is not adjustable. A clearance specification has been established for manufacturing tolerances. If the clearance is not within these specifications, then either the WSS or other components may be damaged. The clearance between the WSS and the exciter ring is 0.005 - 0.050 inch . The assembly plant performs a "Rolls Test" on every vehicle that leaves the assembly plant. One of the test performed is a test of the WSS. To properly test the sensor, the assembly plant connects test equipment to the Data Link Connector (DLC) . This connector is located to the left of the steering column and attached to the lower portion of the instrument panel. The rolls test terminal is spliced to the WSS circuit. The vehicle is then driven on a set of rollers and the WSS output is monitored for proper operation.
In addition to determining distance and vehicle speed, the output from the sensor is used to help control:
Speed control operation
Transmission overdrive operation
Transmission torque converter electrical operation