Troubleshooting Transmissions

Championship Service

Transmission Light Flashing
A check engine or check transmission light is flashing.


Possible Cause:
A transmission fault has occurred requiring a qualified technician to read the vehicle computer codes for troubleshooting. Problems may range from external control devices such as speed sensors, electronic linkage, torque converter, clutches and solenoids.


No Movement
Your engine seems to be operating correctly, but when you step on the gas pedal or try to shift into gear your transmission does not move the vehicle in either reverse or forward.


Possible Cause:
Automatic: Check transmission fluid levels. Excessive transmission leaks or loose fluid lines can quickly empty your transmission of critical fluids. Without fluid, your transmission will become seriously damaged.


If your fluid level is appropriate, you may have a internal hard part damage, a fault with the physical shift linkage, or electrical control signal fault to the transmission.


Manual: As long as the clutch pedal does not have sloppy movement, you may need a minor adjustment. However, your clutch may have been damaged requiring replacement. Low transmission fluid level, input shaft broken, axel broken or loose. Call our service manager (408) 286-5350 to get extra trouble shooting help.


Transmission is Slipping
Automatic: The engine revs up during shifts as the throttle is depressed, however the car does not accelerate. The further you press on the gas pedal, the more noticeable the problem is.


Possible Cause: Clutch Packs, throttle cable out of adjustment, pressure control or shift solenoid faulty, faulty speed sensor, plugged catalytic converter, faulty engine controls sensors such as mass air flow & map sensors


Manual: As you step on the gas with the transmission in gear and the clutch peddle released, the engine revs, but the car moves very little or not at all. The clutch feels like it is slipping. This malfunction gets worse with time and should be corrected immediately to avoid additional damage to the clutch system.


Possible Cause: Clutch kit, Clutch Adjustment, Clutch Master/Slave Cylinder needs Service or Repair


Transmission Rattles and Clunks
Automatic: Transmission vibrates during gear changes, hard shift or thuds when put into gear, clunk noise when placed in four wheel drive. Start by checking your transmission fluid. Make sure it is filled to the level specified in your vehicle manual. If transmission fluid color is brownish and not clear red, service the transmission asap. Plugged transmission filter, worn u-joints, excessive differential backlash, worn transfer case unit, worn leaf springs, broken catalytic converter, worn syncros, broken motor or transmission mounts, CV joints, U-Joints.


Manual: Transmission makes a thudding noise when you change gears. Or, you hear a metallic grinding noise as you shift gears even though you fully press down the clutch pedal and the clutch is completely free.


Possible Cause: Worn syncros, broken Motor or Transmission Mounts, CV joints, U-Joints, Transfer Case Unit, Clutch Kit, Clutch Adjustment, Clutch Master/Slave Cylinder needs Service or Repair


Transmission leaks fluid
You may see red or brown fluid underneath your car. Transmission fluid leaks may develop in several areas of the transmission.


Leaks may lead to additional damage if left to continue. It is normal for a leak to develop under various conditions. Metal contractions due to temperature changes can create a leak. Brittle gaskets may properly seal once it is warmed by operation and coated with fluid. Remember to check the fluid level and quality before long trips. Normal transmission fluid is pink and does not have a sulfurous, or burnt, smell. Call our service manager at (408) 286-5350 for further information.


Possible Cause:
gaskets, cracked cases, loose or detached fluid lines, damaged pan gasket, cracked torque converter hub, or aged seals and gaskets. It is possible that leaks may only occur under specific circumstances such as temperature variations or driving conditions.


Inconsistent transmission operation
You may notice that your transmission works, but is inconsistent. For example, it may only work when warm, or only for a few miles before acting-up. Heat changes can cause metal and rubber parts to allow fluid to leak or may lack the correct pressure at the wrong time.


Possible Cause:
Electrical sensors such as TCP, speed sensors and solenoids. In addition, a transmission filter can become clogged after minimal driving and cause the transmission to stop working correctly. Re-flash computer w/dealer updates.


Slow Gear Changes
Automatic: Car takes longer than normal to shift into drive. You can move the shift lever into gear but the car delays before engagement.


Possible Reasons:
Low transmission fluid
Internal hard part problem
Engine idle needs adjustment
Clogged fluid filter
Torque converter drain back
Re-flash computer w/dealer updates


Premature Shifts
Automatic: Automobile loses power between shift changes. The gears change too quickly.


Possible Reasons:
Throttle linkage needs adjustment
Internal hard part problem
Electrical, solenoid or computer control malfunction
Re-flash computer w/dealer updates


Delayed Up-shifts
Automatic: Shifts happen too late. You feel the engine rev and the power increase, but it decreases just before the next shift. You feel an extended engine revving before the gears shift into the next gear. Call our service manager (408) 286-5350.


Possible Reasons:
Plugged catalytic converter
Engine timing
Plugged fuel filters
Throttle linkage needs adjustment
Internal hard part problem
Engine electrical sensors
Electrical or computer malfunction
Clogged transmission fluid filter
Vacuum controls need adjustment
Re-flash computer w/dealer updates


Delayed Reverse Shifts
Automatic: There is an long delay when you shift the lever to reverse. Other than delayed engagement, the car operates fine.


Possible Reasons:
Band adjustments (specific units)
Fluid level too low
Internal damage to transmission
transmission fluid has gone bad (color brown) or is contaminated,
and/or there is a clogged filter


No Up-Shift
Automatic: Car is moving forward, speeding up and will not shift into the next gear as you press the gas pedal. Malfunction starts out gradually then begins to degrade.


Possible Reasons:
Shift linkage out of adjustment
Plugged catalytic converter
Shift solenoid stuck or broken
Line pressure too low
Speed sensor failure
Throttle cable stuck or out of adjustment
Internal hard part problem
Throttle cable needs adjustment or replacement
Vacuum controls need adjustment or replacement
Electrical or computer control failure
Re-flash computer w/dealer updates


Clutch Pedal Loses Tension; Drops to Floor with no Resistance
Manual/ Standard : Clutch pedal is loose. Pedal presses to the floor without resistance. Gears won’t change even when clutch pedal is pressed down.


Possible Reasons:
Detached clutch cable
Worn Pressure Plate/disk
Fractured clutch disk
Fracture clutch cable
Hydraulic problems
Clutch Master/Slave Cylinder Needs Service or Repair


Clutch Pedal works, but Gears don’t Shift
Manual/ Standard : The gear shifter will not move even when clutch is pressed down.


Possible Reasons:
Shift linkage is bound
Shifter garments broken
Internal hard part problem
Clutch will not release


Car drops out of gear
Manual/ Standard: Car shifts into neutral when you accelerate or decelerate. Call our service manager (408) 286-5350.


Possible Reasons:
Internal hard part problem
Shift linkage out of adjustment
Low fluid level
Broken or out of adjustment Bands
Governor pressure sensors faulty
Speed sensor faulty
Shift solenoid faulty


Harsh Up-Shifts
Automatic: Car thuds into gear. Shifts feel firmer than normal. You feel a bang as the car shifts to next gear.


Possible Reasons:
Wrong transmission fluid type
Fluid is too low
Fluid is burnt or contaminated
Internal failure
Engine idle needs adjustment
Constant velocity “CV” Joint damaged
Universal joint is damaged
Broken motor & transmission mounts
Transmission in fail-safe causing high line pressure
Throttle linkage is lose or damaged
Vacuum controls incorrect
Adaptive strategy cleared w/battery replacement
Re-flash computer w/dealer updates


Harsh Down-shifts
Automatic: Car shifts down into gear with a clunk when you release pressure off the throttle pedal. Firm downshift while passing. Down shifting is fine when you suddenly accelerate to pass, but the down shift should not feel overly abrupt.


Possible Reasons:
Throttle linkage damaged
Wrong type of transmission fluid
Low transmission fluid
Internal hard part problem
Engine malfunction
Electrical or computer damage
Vacuum controls need correction
Mass and speed sensor
TPS adjustments
High line pressure
Adaptive strategy cleared w/battery replacement
Re-flash computer w/dealer updates


Lack of Power
Feels sluggish
Accelerator to the floor to move vehicle


Possible Reasons:
Engine control issues
Torque converter failure
Wrong gear starts from faulty shift solenoid


Transmission Winning Sound


Possible Reasons:
Torque converter
Restricted transmission filter
Vacuum leaks
High line pressure
Valve body issues with factor updates not installed


Grinding While Shifting Gears
Manual/ Standard: The transmission makes a metallic sound and is difficult to shift into gear. The gear lever shudders and the transmission grinds.


Possible Reasons:
Worn clutch surface
Internal hard part problem
Needs clutch adjustment
Shift linkage fractured or damaged


Leale's Transmission & Auto Repair

405 Keyes Street

San Jose, CA 95112

Office (408) 286-5350

Fax    (408)286 5711