If your mechanic tells you ........ you need a new transmission
You need to ask yourself: Did they scan your TCM for DTC’s ?
Did you know that on computer controlled vehicles a minor problem can feel like a major one. Especially with codes MLPS, TPS, or VSS. Even a PCM or PROM or a faulty charging system cam make your vehicle feel like it needs a new transmission and these are external fixes, internal fixes that are sometimes minor repairs that could be a TCCS, EPC, or OOS.
Sounds confusing doesn’t it ?
Here are a list of common transmission terms and abbreviations:
- DTC’s - Diagnostic Trouble Codes (Information that the computer gives you about a problem you have)
- EXTERNAL items:
- Fancy names for neutral safety switches
- MLPS - Manual lever position switch
- Without it the computer doesn’t know what gear you have selected
- PNP - Park / Neutral switch -same as MLPS
- TRS - Transmision range selector - same as MLPS
- Fancy names for accelerator lever
- TPS - Throttle position sendor
- This tells the computer how much gas you a applying. It also controls passing gear selection.
- TPP - Throttle position potentiometer - same as TPS
- FIPL - Fuel injection pump lever - same as TPS
- DBW - Drive by wire - same as TPS only fully electronic
- Fancy names for speedometer
- VSS - vehicle speed sensors
- This tells tells the computer how fast you are going so it knows when to shift
- TSS - Turbine speed sensor - same as VSS
- OSS - Output shaft speed - same as VSS
- ISS - Input speed sensor
- This tells the computer how fast the transmission is spinning.
- PSOM - Programmable speedometer odometer module
- This tells the computer speed with a tamper proof odometer readout.
- Fancy names for the computer
- PCM - Powertrain control module
- This computer can control motor and transmission
- TCM - Transmission control module
- This is the transmission computer
- VCM - Vehicle control module - same as PCM
- ECM - Engine control module
- This is usually engine control only
- TTVA - Transmission throttle valve actuator
- Tells the transmission how you are pressing on the throttle
- PROM - Programmable Read Only Memory
- This is the computer chip that goes into a PCM that contains the manufacturer’s engine and transmission settings for your specific vehicle’s options and features.
- INTERNAL items:
- EPC - Electronic pressure control
- This controls shift feel in all ranges
- TCCS - Torque converter clutch solenoid
- This controls clutch activation (“lockup”)
- TFT - Transmission fluid temperature
- This usually means transmission has overheated
- TOT - Transmission oil temperature - same as TFT
- PCS - Pressure control solenoid - same as EPC
- SS1-5 / SSA-E - Shift solenoid
- This tells you that there is a fault on a specific solenoid
All of the above items control shift strategy
- EGR - Exhaust gas re-circulation
- SRS - Supplemental restraint system
- RABS - Rear wheel antilock brake system
- SES - Service engine soon
- Maintenance required indicator
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