1995 Buick Century Transmission Speed Sensor
12-11-2016, 04:33 PM
#1
1995 Buick Century Transmission Speed Sensor
The Codes indicate this part needs to be replaced however the suggested replacement part from the Auto Zone Data Base failed to function properly. We contacted GM who says the part is no longer manufactured for this year. The transmission is slipping. How can I locate a used or compatible replacement Transmission Speed Sensor for this car or are there any other suggestions? My wife LOVES this car and I don't want to have to scrap it over a small part. 
Thank you. 
Thank you.
12-11-2016, 06:23 PM
#2
Retired
Certified Car Nut
If the trans is slipping, the speed sensor is the least of your worries. Consider a trans rebuild in the near future. And that will probably exceed the value of your car.
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2002 *-10 5.7 V8
2023 Jeep Rubicon Diesel
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2002 *-10 5.7 V8
2023 Jeep Rubicon Diesel
12-11-2016, 08:00 PM
#3
I've had the tranny rebuilt about 6 years ago.
It'* the sensor.
12-11-2016, 10:59 PM
#4
Senior Member
True Car Nut
What is the exact code being thrown?
I am afraid I also don't see how this can cause the tranny to slip. It seems like it would just cause it to hunt if anything.
Also, which engine does this car have?
I am afraid I also don't see how this can cause the tranny to slip. It seems like it would just cause it to hunt if anything.
Also, which engine does this car have?
12-12-2016, 04:37 PM
#5
My wife told me it is "slipping" but I suspect you are right - it is hunting. I saw the code as "Transmission Speed Sensor" but do not have the exact Code onhand currently. The mechanic said there could be a problem locating an obsolete sensor and that a generically suggested one might not work.
I did disconnect the battery for 10 minutes after installing the autozone one to help to recognize the replacement but the new sensor exacerbated the problem.
Thank you for any suggestion or ideas!
12-12-2016, 07:44 PM
#6
Senior Member
True Car Nut
I am afraid I won't be much help without knowing the exact code.
Also looking around, I see that the VSS seems to be a part that can readily be ordered in, it'* just a matter of selecting whether you have a 3 or 4 speed transmission. If it'* 4 speed, it'* likely the 4t60e which was put in just about every FWD V6 GM until 96-97. The part should either fit, or not fit.
One possible theory is that there is a wiring issue, causing the VSS signal to drop out, which would cause the indicated speed to drop, the computer to freak (and in turn the tranny), and codes to fly across both the engine and ABS computers. If this is the case, the fiddling that would be involved in changing the VSS could aggravate the issue.
I have also learned that sometimes the scanners have generic titles for codes, which may apply differently from vehicle to vehicle, especially from Pre-OBDII vehicles. That'* one of the other reasons I make note of the precise code.
Also looking around, I see that the VSS seems to be a part that can readily be ordered in, it'* just a matter of selecting whether you have a 3 or 4 speed transmission. If it'* 4 speed, it'* likely the 4t60e which was put in just about every FWD V6 GM until 96-97. The part should either fit, or not fit.
One possible theory is that there is a wiring issue, causing the VSS signal to drop out, which would cause the indicated speed to drop, the computer to freak (and in turn the tranny), and codes to fly across both the engine and ABS computers. If this is the case, the fiddling that would be involved in changing the VSS could aggravate the issue.
I have also learned that sometimes the scanners have generic titles for codes, which may apply differently from vehicle to vehicle, especially from Pre-OBDII vehicles. That'* one of the other reasons I make note of the precise code.
12-13-2016, 11:18 PM
#7
Senior Member
True Car Nut
As any Tech, worth his salt will tell you, the problem is not necessarily, the part that the code is named after.....
A code can be caused by anything in the circuit, or anything that affects the circuit......for example, you have an O2 sensor code.....does that mean it'* the O2 sensor? No......it could be anything in the circuit, like the wiring, connector, the sensor, the PCM, etc. Also, it can be anything that affects the sensor, like a vacuum leak, a leaking injector, a misfire, etc.
That'* why rjolly87 asks for the exact code....like he said, you could have a wiring/connection problem, instead of a sensor problem....
If the tranny was slipping, there should be more transmission codes set....
A road test with a scan tool taking a snapshot is the way to go....
A code can be caused by anything in the circuit, or anything that affects the circuit......for example, you have an O2 sensor code.....does that mean it'* the O2 sensor? No......it could be anything in the circuit, like the wiring, connector, the sensor, the PCM, etc. Also, it can be anything that affects the sensor, like a vacuum leak, a leaking injector, a misfire, etc.
That'* why rjolly87 asks for the exact code....like he said, you could have a wiring/connection problem, instead of a sensor problem....
If the tranny was slipping, there should be more transmission codes set....
A road test with a scan tool taking a snapshot is the way to go....
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PatrickB (12-14-2016)
02-03-2017, 01:31 PM
#8
The Codes:
HISTORY CODES
Transmission Codes:
502 Vehicle Speed Sensor Failure (after being replaced with a new VSS)
501 " " "
740 Torque Converter Failure
NO CURRENT CODES
Coolant line Leaking for Transmission
Transmission Codes:
502 Vehicle Speed Sensor Failure (after being replaced with a new VSS)
501 " " "
740 Torque Converter Failure
NO CURRENT CODES
Coolant line Leaking for Transmission
02-03-2017, 10:26 PM
#9
Senior Member
True Car Nut
I would start here: https://www.obd-codes.com/p0502
I wouldn't jump to conclusions about P0740 until after the speed sensor concerns are sorted out and the code comes back.
Symptoms of a P0502 code may include:
Erratic speedometer/odometer operation
Irregular transmission shift patterns
Illumination of the service engine soon lamp, traction control lamp, or antilock brake lamp
Unexpected activation/deactivation of the traction control system (if equipped)
Other transmission and ABS codes may be stored
The ABS system may be rendered inoperable in some cases
Possible causes for this code include:
Excessive metal debris buildup on speed sensor/*
A defective wheel speed or vehicle speed sensor
Cut or otherwise damaged wiring harnesses or connectors (especially near speed sensors)
Damaged or worn teeth on a reluctor ring
A faulty PCM, ABCM, or EBCM
Related vehicle speed sensor trouble codes:
P0500 Vehicle Speed Sensor "A" Malfunction
P0501 Vehicle Speed Sensor "A" Range/Performance
P0503 Vehicle Speed Sensor "A" Intermittent/Erratic/High
I normally like to begin my diagnosis of a P0502 with a visual inspection of system wiring, speed sensors, and connectors. Repair open or shorted circuits as required and clean excessive metallic debris from effected sensors. Check reluctor ring integrity when inspecting the sensor. Connect the scanner to the vehicle diagnostic port and retrieve all stored trouble codes and available freeze-frame data. Before clearing the codes, write this information down as it may prove helpful as your diagnosis progresses. Using your vehicle information source, search applicable technical service bulletins (TSB). If you locate a TSB that matches the symptoms and stored codes of the vehicle in question, the diagnostic information contained therein will likely aid in diagnosing the P0502 from here. Utilize the scanner data stream to observe wheel speed and vehicle speed while test driving the vehicle. You may narrow the data stream to display only pertinent fields to increase the speed and accuracy at which the desired data is delivered. Inconsistent or erratic readings from VSS or wheel speed sensors may lead you to wiring, electrical connector, or sensor problems by narrowing the general area of the system malfunction.
Erratic speedometer/odometer operation
Irregular transmission shift patterns
Illumination of the service engine soon lamp, traction control lamp, or antilock brake lamp
Unexpected activation/deactivation of the traction control system (if equipped)
Other transmission and ABS codes may be stored
The ABS system may be rendered inoperable in some cases
Possible causes for this code include:
Excessive metal debris buildup on speed sensor/*
A defective wheel speed or vehicle speed sensor
Cut or otherwise damaged wiring harnesses or connectors (especially near speed sensors)
Damaged or worn teeth on a reluctor ring
A faulty PCM, ABCM, or EBCM
Related vehicle speed sensor trouble codes:
P0500 Vehicle Speed Sensor "A" Malfunction
P0501 Vehicle Speed Sensor "A" Range/Performance
P0503 Vehicle Speed Sensor "A" Intermittent/Erratic/High
I normally like to begin my diagnosis of a P0502 with a visual inspection of system wiring, speed sensors, and connectors. Repair open or shorted circuits as required and clean excessive metallic debris from effected sensors. Check reluctor ring integrity when inspecting the sensor. Connect the scanner to the vehicle diagnostic port and retrieve all stored trouble codes and available freeze-frame data. Before clearing the codes, write this information down as it may prove helpful as your diagnosis progresses. Using your vehicle information source, search applicable technical service bulletins (TSB). If you locate a TSB that matches the symptoms and stored codes of the vehicle in question, the diagnostic information contained therein will likely aid in diagnosing the P0502 from here. Utilize the scanner data stream to observe wheel speed and vehicle speed while test driving the vehicle. You may narrow the data stream to display only pertinent fields to increase the speed and accuracy at which the desired data is delivered. Inconsistent or erratic readings from VSS or wheel speed sensors may lead you to wiring, electrical connector, or sensor problems by narrowing the general area of the system malfunction.
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PatrickB (02-04-2017)
02-04-2017, 12:29 AM
#10
ABS Codes
Thank you for your thoughtful and insightful response!
We are also showing these ABS CODES {and the ABS light is on though the intermittently on Check Engine Light is now off}:
11 Warning Light open or Short to Ground
36 System Voltage Low
66 Rear ABS Motor Short to Voltage
86 Turned on Red Brake Light
94 Brake switch Circiut Shorted (The rear center break light is melted)
Interestingly, there were coolant system problems such as collapsed hoses when car cools down and a loose radiator core hose which were just fixed; since that repair the transmission symptoms seem to have abated but it is only one day so far.
We are also showing these ABS CODES {and the ABS light is on though the intermittently on Check Engine Light is now off}:
11 Warning Light open or Short to Ground
36 System Voltage Low
66 Rear ABS Motor Short to Voltage
86 Turned on Red Brake Light
94 Brake switch Circiut Shorted (The rear center break light is melted)
Interestingly, there were coolant system problems such as collapsed hoses when car cools down and a loose radiator core hose which were just fixed; since that repair the transmission symptoms seem to have abated but it is only one day so far.