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Diagnostics · System playbook

Transmission

Fluid first. Always fluid first.

More transmissions are condemned over fluid level, fluid condition, or a $40 speed sensor than actual hard-part failure. Modern units are computer-controlled and log their own evidence — shift adapts, slip counts, temperature history. Read the evidence before quoting the big job; the difference is thousands.

What the symptoms mean

Harsh 1-2 shift when cold only
Fluid viscosity/level or normal cold strategy — verify before alarm
Slipping under load, worse when hot
Low fluid, worn clutches, or converter — pressure test tells which
No reverse
Specific clutch/band failure — this one usually IS internal
Shudder at light throttle 40-50 mph
Torque converter clutch — often a fluid service fixes it if caught early
Stuck in one gear, no codes
Limp mode via lost communication or power — check fuses and connectors first

The diagnostic order

Work top to bottom — the order is the point. Each step rules out the cheapest, most common causes before anything expensive gets blamed.

  1. Fluid level AND condition, by the book (many need a scan tool and exact temperature now). Burnt smell or glitter changes the whole conversation.
  2. Pull codes from the TRANSMISSION module, not just the engine — generic scanners miss half the story.
  3. Review adapts/slip data: a unit that has been quietly compensating for months shows it in the numbers.
  4. Line pressure test where accessible: pressure that follows spec at idle but collapses under load is a pump/valve-body conversation.
  5. Verify the basics before internal blame: battery voltage, grounds, and the range sensor cause more "transmission problems" than clutches do.

Tools that matter here

Scan tool with transmission module accessPressure gauge setThe correct fluid — not "universal", the CORRECT one

The classic mistakes

  • Quoting overhaul off a symptom without pulling transmission-module codes.
  • Topping with the wrong fluid — some units are genuinely fluid-specific and shudder on anything else.
  • Skipping the relearn procedure after service on adapt-heavy units and returning a "worse" transmission.
Pro tip: A shudder that improves during a test drive after a fluid exchange is your green light that the converter clutch was surviving on dirty fluid. Caught early, that is a service, not a transmission.

Transmission trouble codes (250)

P0218Transmission Over Temperature Cond…P0613TCM ProcessorP0700Transmission Control System (MIL R…P0701Transmission Control System Range/…P0702Transmission Control System Electr…P0704Clutch Switch Input Circuit Malfun…P0705Transmission Range Sensor Circuit …P0706Transmission Range Sensor Circuit …P0707Transmission Range Sensor Circuit …P0708Transmission Range Sensor Circuit …P0709Transmission Range Sensor Circuit …P0710Transmission Fluid Temperature Sen…P0711Transmission Fluid Temperature Sen…P0714Transmission Fluid Temperature Sen…P0715Input/Turbine Speed Sensor CircuitP0716Input/Turbine Speed Sensor Circuit…P0717Input/Turbine Speed Sensor Circuit…P0718Transmission Fluid Temperature Sen…P0719Torque Converter/Brake Switch B Ci…P0720Output Speed Sensor CircuitP0721Output Speed Sensor Circuit Range/…P0722Output Speed Sensor Circuit No Sig…P0723Torque Converter/Brake Switch B Ci…P0724Torque Converter/Brake Switch B Ci…P0725Engine Speed Input Circuit Malfunc…P0726Engine Speed Input Circuit Range/P…P0727Engine Speed Input Circuit No Sign…P0728Engine Speed Input Circuit Intermi…P0729Gear 6 Incorrect RatioP0730Incorrect Gear RatioP0731Gear 1 Incorrect RatioP0732Gear 2 Incorrect RatioP0733Gear 3 Incorrect RatioP0734Gear 4 Incorrect RatioP0736Reverse Incorrect RatioP0737TCM Engine Speed Output CircuitP0738TCM Engine Speed Output Circuit Lo…P0740Torque Converter Clutch Circuit Ma…P0741Torque Converter Clutch Circuit Pe…P0742Torque Converter Clutch Circuit St…P0745Pressure Control Solenoid A Malfun…P0746Pressure Control Solenoid A Perfor…P0747Pressure Control Solenoid A Stuck …P0749Pressure Control Solenoid A Interm…P0750Shift Solenoid AP0751Shift Solenoid A Performance/Stuck…P0752Shift Solenoid A Stuck OnP0753Shift Solenoid A ElectricalP0754Shift Solenoid A IntermittentP0755Shift Solenoid BP0756Shift Solenoid B Performance/Stuck…P0757Shift Solenoid B Performance/Stuck…P0758Shift Solenoid B ElectricalP0759Shift Solenoid B IntermittentP0760Shift Solenoid CP0761Shift Solenoid C Performance/Stuck…P0762Shift Solenoid C Stuck OnP0763Shift Solenoid C ElectricalP0764Shift Solenoid C IntermittentP0765Shift Solenoid DP0766Shift Solenoid D Performance or St…P0767Shift Solenoid D ElectricalP0768Shift Solenoid D IntermittentP0769Shift Solenoid E MalfunctionP0770Shift Solenoid EP0771Shift Solenoid E Performance or St…P0772Shift Solenoid E ElectricalP0773Shift Solenoid E IntermittentP0774Shift Solenoid E ElectricalP0775Pressure Control Solenoid BP0776Pressure Control Solenoid B Perfor…P0777Pressure Control Solenoid B Stuck …P0778Pressure Control Solenoid B Electr…P0779Pressure Control Solenoid B Interm…P0780Shift MalfunctionP07811-2 Shift MalfunctionP07822-3 Shift MalfunctionP07833-4 Shift MalfunctionP07844-5 Shift MalfunctionP0785Shift/Timing Solenoid MalfunctionP0786Shift/Timing Solenoid Range/Perfor…P0787Shift/Timing Solenoid LowP0788Shift/Timing Solenoid HighP0789Shift/Timing Solenoid IntermittentP0790Normal/Performance Switch Circuit …P0791Intermediate Shaft Speed Sensor Ci…P0792Intermediate Shaft Speed Sensor Ci…P0793Intermediate Shaft Speed Sensor Ci…P0794Intermediate Shaft Speed Sensor Ci…P0795Pressure Control Solenoid CP0796Pressure Control Solenoid C Perfor…P0797Pressure Control Solenoid C Stuck …P0798Pressure Control Solenoid C Electr…P0800Transmission Control System (MIL R…P0801Reverse Inhibit Control CircuitP0802Transmission MIL Request Circuit O…P08031-4 Upshift (Skip Shift) Solenoid …P0805Clutch Position Sensor CircuitP0806Clutch Position Sensor Circuit Ran…P0807Clutch Position Sensor Circuit Ran…P0808Clutch Position Sensor Circuit LowP0809Clutch Position Sensor Circuit Hig…P0810Clutch Position Control ErrorP0811Excessive Clutch SlippageP0812Reverse Input CircuitP0813Reverse Output CircuitP0814Transmission Range Display CircuitP0815Upshift Switch CircuitP0816Downshift Switch CircuitP0818Driveline Disconnect Switch Input …P0819Up and Down Shift Switch to Transm…P0820Gear Lever X-Y Position Sensor Cir…P0821Gear Lever X Position CircuitP0822Gear Lever Y Position CircuitP0823Gear Lever X-Position CircuitP0824Gear Lever X-Position Circuit Rang…P0825Gear Lever Push-Pull Switch (Shift…P0826Up and Down Shift Switch CircuitP0827Up and Down Shift Switch Circuit L…P0828Up and Down Shift Switch Circuit H…P08295-6 ShiftP0830Clutch Pedal Switch A CircuitP0831Clutch Pedal Switch "A" CircuitP0832Clutch Pedal Switch "A" Circuit Lo…P0835Clutch Pedal Switch "B" CircuitP0840Transmission Fluid Pressure Sensor…P0841Transmission Fluid Pressure Sensor…P0842Transmission Fluid Pressure Sensor…P0843Transmission Fluid Pressure Sensor…P0844Transmission Fluid Pressure Sensor…P0845Transmission Fluid Pressure Sensor…P0846Transmission Fluid Pressure Sensor…P0847Transmission Fluid Pressure Sensor…P0848Transmission Fluid Pressure Sensor…P0849Transmission Fluid Pressure Sensor…P0850Park/Neutral Switch Input CircuitP0851Park/Neutral Switch Input Circuit …P0852Park/Neutral Switch Input Circuit …P0853Drive Switch Input CircuitP0854Drive Switch Input Circuit LowP0855Drive Switch Input Circuit HighP0858TCM Communication Circuit Range/Pe…P0859TCM Communication Circuit LowP0867Transmission Fluid PressureP0868Transmission Fluid Pressure LowP0869Transmission Fluid Pressure HighP0870Transmission Fluid Pressure Sensor…P0871Transmission Fluid Pressure Sensor…P0872Transmission Fluid Pressure Sensor…P0873Transmission Fluid Pressure Sensor…P0874Transmission Fluid Pressure Sensor…P0875Transmission Fluid Pressure Sensor…P0876Transmission Fluid Pressure Sensor…P0877Transmission Fluid Pressure Sensor…P0878Transmission Fluid Pressure Sensor…P0879Transmission Fluid Pressure Sensor…P0880TCM Power Input SignalP0881TCM Power Input Signal Range/Perfo…P0882TCM Power Input Signal LowP0883TCM Power Input Signal HighP0884TCM Power Input Signal Intermitten…P0885TCM Power Relay Control Circuit/Op…P0886TCM Power Relay Control Circuit Lo…P0887TCM Power Relay Sense Circuit LowP0888TCM Power Relay Sense Circuit HighP0889TCM Power Relay Sense Circuit Rang…P0890TCM Power Relay Sense Circuit Sign…P0891TCM Power Relay Sense Circuit Sign…P0892TCM Power Relay Sense Circuit HighP0893Multiple Clutch A EngagementP0894Transmission Component SlippingP0895Shift Time Too ShortP0896Shift Time Too LongP0897Transmission Fluid DeterioratedP0898Transmission Control System MIL Re…P0899Transmission Control System MIL Re…P0900Clutch Actuator Circuit/OpenP0901Clutch Actuator Circuit Range/Perf…P0902Clutch Actuator Circuit LowP0903Gate Select Actuator Circuit OpenP0904Gate Select Actuator Circuit Range…P0905Gate Select Actuator Circuit LowP0906Gate Select Actuator Circuit HighP0907Gate Select Actuator Circuit Range…P0908Gate Select Actuator Circuit LowP0909Gate Select Actuator Circuit HighP0910Gate Select Actuator Circuit OpenP0911Gate Select Position Circuit Range…P0912Gate Select Position Circuit LowP0913Gate Select Position Circuit HighP0914Gear Shift Position CircuitP0915Gear Shift Position Circuit Range/…P0916Gear Shift Position Circuit LowP0917Gear Shift Position Circuit HighP0918Gear Shift Position Circuit Interm…P0919Gear Shift Position Control ErrorP0920Gear Shift Forward Actuator Circui…P0921Gear Shift Forward Actuator Circui…P0922Gear Shift Forward Actuator Circui…P0923Gear Shift Forward Actuator Circui…P0924Gear Shift Reverse Actuator Circui…P0925Gear Shift Reverse Actuator Circui…P0926Gear Shift Reverse Actuator Circui…P0927Gate Select Position Circuit LowP0928Gear Shift Lock Solenoid Control C…P0929Gear Shift Lock Solenoid Control C…P0930Gear Shift Lock Solenoid Control C…P0931Gear Shift Lock Solenoid Control C…P0932Hydraulic Pressure Sensor CircuitP0933Hydraulic Pressure Sensor Range/Pe…P0934Hydraulic Pressure Sensor Circuit …P0935Hydraulic Pressure Sensor Circuit …P0936Hydraulic Pressure Sensor Circuit …P0937Hydraulic Oil Temperature Sensor C…P0938Hydraulic Oil Temperature Sensor C…P0939Hydraulic Oil Temperature Sensor C…P0940Hydraulic Oil Temperature Sensor C…P0941Hydraulic Oil Temperature Sensor C…P0942Hydraulic Pressure UnitP0943Hydraulic Pressure Unit Cycling Pe…P0944Hydraulic Pressure Unit Loss of Pr…P0945Hydraulic Pump Relay Circuit/OpenP0946Hydraulic Pump Relay Circuit Range…P0947Hydraulic Pump Relay Circuit LowP0948Hydraulic Pump Relay Circuit HighP0949Auto Shift Manual Adaptive Learnin…P0950Auto Shift Manual Control CircuitP0951Auto Shift Manual Control Circuit …P0952Auto Shift Manual Control Circuit …P0953Auto Shift Manual Control Circuit …P0954Auto Shift Manual Control Circuit …P0955Auto Shift Manual Mode CircuitP0956Auto Shift Manual Mode Circuit Ran…P0957Auto Shift Manual Mode Circuit LowP0958Auto Shift Manual Mode Circuit Hig…P0960Pressure Control Solenoid "A" Cont…P0961Pressure Control Solenoid "A" Cont…P0962Pressure Control Solenoid "A" Cont…P0963Pressure Control Solenoid "A" Cont…P0964Pressure Control Solenoid "B" Cont…P0965Pressure Control Solenoid "B" Cont…P0966Pressure Control Solenoid "B" Cont…P0967Pressure Control Solenoid B Contro…P0968Pressure Control Solenoid B Contro…P0969Pressure Control Solenoid C Contro…P0970Pressure Control Solenoid C Contro…P0971Pressure Control Solenoid C Contro…P0972Shift Solenoid A Control Circuit R…P0973Shift Solenoid A Control Circuit L…P0974Shift Solenoid A Control Circuit H…
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