Automatic Transmission, 4l60-e/4l65-e (Troubleshooting) Chevrolet Chevy Express G3500

Symptoms - Automatic Transmission

Symptoms - Automatic Transmission

Scheme 170

Circuit Description

The transmission range (TR) switch is part of the park/neutral position (PNP) and back-up lamp switch assembly, which is externally mounted on the transmission manual shaft. The TR switch contains four internal switches that indicate the transmission gear range selector lever position. The powertrain control module (PCM) supplies ignition voltage to each switch circuit. As the gear range selector lever is moved, the state of each switch may change, causing the circuit to open or close. An open circuit or switch indicates a high voltage signal. A closed circuit or switch indicates a low voltage signal. The PCM detects the selected gear range by deciphering the combination of the voltage signals. The PCM compares the actual voltage combination of the switch signals to a TR switch combination chart stored in memory.

Diagnostic Aids

Refer to Transmission Range Switch Logic for valid combinations of switch signal circuits A, B, C and Parity. On the table, HI indicates an ignition voltage signal. LOW indicates a zero voltage signal.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. 4: By disconnecting the TR switch, the ground path of all TR switch circuits is removed and the PCM should recognize all circuits as open. The scan tool should display HI for all range signal states.
2. 5: This step tests the TR switch wiring for an open or the lack of the signal voltage from the PCM.
3. 6: This step tests the TR switch wiring and the PCM by providing a ground path through a fused jumper wire. When grounded, the scan tool range signal states should change to LOW.
4. 7: This step tests the TR switch wiring and the PCM by providing a ground path through a fused jumper wire. When grounded, the scan tool range signal states should change to LOW.
5. 8: This step tests the TR switch wiring and the PCM by providing a ground path through a fused jumper wire. When grounded, the scan tool range signal states should change to LOW.
6. 9: This step tests the TR switch wiring and the PCM by providing a ground path through a fused jumper wire. When grounded, the scan tool range signal states should change to LOW.

Range Selector Displays Incorrect Range

Scheme 171

Tow/haul mode enables the operator to achieve enhanced shift performance when towing or hauling a load. When tow/haul mode is selected, the tow/haul switch input signal to the body control module (BCM) is momentarily toggled to zero volts. This signals the powertrain control module (PCM) to extend the length of time between upshifts and increase transmission line pressure. Cycling the tow/haul switch again disables tow/haul mode and returns the transmission to a normal shift pattern.

If the electrical circuit tests are OK and the tow/haul shift pattern is not occurring, there may be a mechanical/hydraulic condition that prevents tow/haul operation. Refer to Symptoms - Automatic Transmission .

The numbers below refer to the step numbers on the diagnostic table.

1. 2: This step tests for a faulty tow/haul switch.
2. 3: This step tests for voltage input from the BCM to the tow/haul switch.
3. 6: This step tests for ground integrity.

Tow/Haul Switch/Indicator Always On or Inoperative

Transmission Fluid Checking Procedure

1. Start the engine and operate the vehicle for 15 minutes or until the transmission fluid reaches an operating temperature of 82-93°C (180-200°F).
2. Park the vehicle on a level surface.
3. With your foot on the brake, move the shift lever through each gear range. Pause for about 3 seconds in each range, ending in PARK.
4. Apply the parking brake and let the engine idle for 3 minutes.
5. Remove the transmission fluid level indicator. Wipe the indicator clean. Insert the indicator. Give the indicator a full twist in order to close.
6. Wait 3 seconds and remove the indicator.
7. Read both sides of the indicator. The fluid must be within the hot cross-hatched area using the lowest level reading.

Transmission Fluid Checking Procedure

Tools Required

J 21867 Pressure Gage

Scheme 172

Line Pressure Check Procedure

1. Install a scan tool. CAUTION: Keep the brakes applied at all times in order to prevent unexpected vehicle motion. Personal injury may result if the vehicle moves unexpectedly. IMPORTANT: Before performing the line pressure check, verify that the transmission pressure control (PC) solenoid is operating correctly.
2. Start the engine.
3. Inspect the transmission for the proper fluid levels. Refer to «Transmission Fluid Checking Procedure»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l60-e4l65-e-troubleshooting__transmission-fluid-checking-procedure) .
4. Use the scan tool to inspect for any active or stored diagnostic trouble codes.
5. Inspect the manual linkage at the transmission for proper function.
6. Turn the engine OFF.
7. Remove the pressure plug.
8. Install the J 21867 .
9. Access the Scan Tool Output Control for the PC Solenoid.
10. Start the engine.
11. Begin commanding PC Solenoid at 1.0 amp and lower the amperage in one-tenth increments (0.01) until maximum line pressure is achieved.
12. Allow the pressure to stabilize between increments.
13. Compare your pressure readings to the Line Pressure table. Refer to «Line Pressure»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l60-e4l65-e-introduction-service-replacement__line-pressure) .
14. If the pressure readings vary greatly from the line pressure table, refer to «Oil Pressure High or Low»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l60-e4l65-e-troubleshooting__oil-pressure-high-or-low) .
15. Turn the engine OFF.
16. Remove the J 21867 .
17. Install the pressure plug. Tighten: Tighten the pressure plug to 8-14 N.m (6-10 lb ft).

Road Test Procedure

The following test provides a method of evaluating the condition of the automatic transmission. The test is structured so that most driving conditions would be achieved. The test is divided into the following parts

1. Electrical Function Check
2. Upshift Control and Torque Converter Clutch (TCC) Apply
3. Part Throttle Detent Downshifts
4. Full Throttle Detent Downshifts
5. Manual Downshifts
6. Coasting Downshifts
7. Manual Gear Range Selection REVERSE Manual FIRST Manual SECOND Manual THIRD

Before the road test, ensure the following

1. The engine is performing properly.
2. Transmission fluid level is correct. Refer to the «Transmission Fluid Checking Procedure»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l60-e4l65-e-troubleshooting__transmission-fluid-checking-procedure) .
3. Tire pressure is correct.

During the road test

1. Perform the test only when traffic conditions permit.
2. Operate the vehicle in a controlled, safe manner.
3. Observe all traffic regulations.
4. View the scan tool data while conducting this test. Take along qualified help in order to operate the vehicle safely.
5. Observe any unusual sounds or smells.

After the road test, check the following

1. Transmission fluid level. Refer to the «Transmission Fluid Checking Procedure»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l60-e4l65-e-troubleshooting__transmission-fluid-checking-procedure) .
2. Diagnostic trouble codes (DTCs) that may have set during the testing. Refer to the applicable DTC.
3. Scan tool data for any abnormal readings or data.

Electrical Function Check

Perform this check first, in order to ensure the electronic transmission components are connected and functioning properly. If these components are not checked, a simple electrical condition could be mis-diagnosed.

1. Connect the scan tool.
2. Ensure the gear selector is in PARK and set the parking brake.
3. Start the engine.
4. Verify that the following scan tool data can be obtained and is functioning properly. Refer to «Scan Tool Data List»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l60-e4l65-e-diagnostic-information-procedures__scan-tool-data-list) for typical data values. Data that is questionable may indicate a concern. Engine speed Transmission output speed Vehicle speed TFP manual valve position switch Transmission range, engine list Commanded gear, current gear PC solenoid reference current PC solenoid actual current PC solenoid duty cycle Brake switch Engine coolant temperature Transmission fluid temperature Throttle angle Ignition voltage 1-2 shift solenoid 2-3 shift solenoid TCC solenoid duty cycle TCC slip speed
5. Monitor the brake switch signal while depressing and releasing the brake pedal. The scan tool should display: Closed when the brake pedal is released. Open when the brake pedal is depressed.
6. Check the garage shifts. Apply the brake pedal and ensure that the parking brake is set. Move the gear selector through the following ranges: PARK to REVERSE REVERSE to NEUTRAL NEUTRAL to DRIVE Pause 2 to 3 seconds in each gear position. Verify the gear engagements are immediate and not harsh.
7. Monitor transmission range on the scan tool, engine list. Apply the brake pedal and ensure the parking brake is set. Move the gear selector through all ranges. Pause 2-3 seconds in each range. Return gear selector to PARK. Verify that all selector positions match the scan tool display.
8. Check throttle angle input. Apply the brake pedal and ensure that the parking brake is set. Ensure the gear selector is in PARK. Monitor throttle angle while increasing and decreasing engine speed with the throttle pedal. The scan tool throttle angle should increase and decrease with engine speed.

If any of the above checks do not perform properly, record the result for reference after completion of the road test.

Upshift Control and Torque Converter Clutch (TCC) Apply

The PCM calculates the upshift points based primarily on two inputs: throttle angle and vehicle speed. When the PCM determines that conditions are met for a shift to occur, the PCM commands the shift by closing or opening the ground circuit for the appropriate solenoid.

Perform the following steps

1. Refer to the «Shift Speed»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l60-e4l65-e-introduction-service-replacement__shift-speed) table in this section and choose a throttle position of 12 percent, 25 percent or 50 percent. All throttle angles shown should be tested to cover the normal driving range.
2. Monitor the following scan tool parameters: Throttle angle Vehicle speed Engine speed Output shaft speed Commanded gear Slip speed Solenoid states
3. Place the gear selector in the OVERDRIVE position.
4. Accelerate the vehicle using the chosen throttle angle. Hold the throttle steady.
5. As the transmission upshifts, note the vehicle speed when the shift occurs for each gear change. There should be a noticeable shift feel or engine speed change within 1-2 seconds of the commanded gear change.
6. Compare the shift speeds to the Shift Speed table. Refer to «Shift Speed»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l60-e4l65-e-introduction-service-replacement__shift-speed) . Shift speeds may vary slightly due to transmission fluid temperature or hydraulic delays in responding to electronic controls. Note any harsh, soft or delayed shifts or slipping. Note any noise or vibration.
7. Repeat steps 1 through 6 to complete all throttle angles.
8. Check for TCC apply in THIRD and FOURTH gear. Note the TCC apply point. When the TCC applies there should be a noticeable drop in engine speed and a drop in slip speed to below 100 RPM. If the TCC apply can not be detected: Check for DTCs. Refer to «Torque Converter Diagnosis Procedure»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l60-e4l65-e-troubleshooting__torque-converter-diagnosis-procedure) . Refer to the «Shift Speed»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l60-e4l65-e-introduction-service-replacement__shift-speed) table for the correct apply speeds. Lightly tap and release the brake pedal. The TCC will release on most applications.

Part Throttle Detent Downshift

1. Place the gear selector in the OVERDRIVE position.
2. Accelerate the vehicle to 64-88 km/h (40-55 mph) in FOURTH gear.
3. Quickly increase throttle angle to greater than 50 percent.
4. Verify the following: The TCC releases The transmission downshifts immediately to THIRD gear

Full Throttle Detent Downshift

1. Place the gear selector in the OVERDRIVE position.
2. Accelerate the vehicle to speeds of 64-88 km/h (40-55 mph) in FOURTH gear.
3. Quickly increase throttle angle to 100 percent wide open throttle (WOT).
4. Verify the following: The TCC releases The transmission downshifts immediately to SECOND gear

Manual Downshifts

The shift solenoid valves do not control the initial downshift for the 4-3 or the 3-2 manual downshifts. The 4-3 and the 3-2 manual downshifts are hydraulic. The 2-1 manual downshift is electronic. The solenoid states should change during or shortly after a manual downshift is selected.

Manual 4-3 Downshift

1. Place the gear selector in the OVERDRIVE position.
2. Accelerate the vehicle to 64-88 km/h (40-55 mph) in FOURTH gear.
3. Release the throttle while moving the gear selector to THIRD.
4. Verify the following: The TCC releases The transmission downshifts immediately to THIRD gear The engine slows the vehicle

Manual 4-2 Downshift

1. Place the gear selector in the OVERDRIVE position.
2. Accelerate the vehicle to 64-72 km/h (40-45 mph).
3. Release the throttle while moving the gear selector to SECOND.
4. Verify the following: The TCC releases The transmission downshifts immediately to SECOND gear The engine slows the vehicle

Manual 4-1 Downshift

1. Place the gear selector in the OVERDRIVE position.
2. Accelerate the vehicle to 48 km/h (30 mph).
3. Release the throttle while moving the gear selector to FIRST.
4. Verify the following: The TCC releases. The transmission downshifts immediately to FIRST gear. The engine slows the vehicle.

Coasting Downshifts

1. Place the gear selector in the OVERDRIVE position.
2. Accelerate the vehicle to FOURTH gear with the TCC applied.
3. Release the throttle and lightly apply the brakes.
4. Verify the following: The TCC releases Downshifts occur at speeds shown in the Shift Speed table. Refer to «Shift Speed»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l60-e4l65-e-introduction-service-replacement__shift-speed) .

Manual Gear Range Selection

The shift solenoids control the upshifts in the manual gear ranges.

Perform the following tests using 10-15 percent throttle angle.

Reverse

1. With the vehicle stopped, move the gear selector to REVERSE.
2. Slowly accelerate the vehicle.
3. Verify that there is no noticeable slip, noise or vibration.

Manual First

1. With the vehicle stopped, move the gear selector to FIRST.
2. Accelerate the vehicle to 32 km/h (20 mph).
3. Verify the following: No upshifts occur The TCC does not apply There is no noticeable slip, noise, or vibration

Manual Second

1. With the vehicle stopped, move the gear selector to SECOND.
2. Accelerate the vehicle to 57 km/h (35 mph).
3. Verify the following: The 1-2 shift occurs The 2-3 shift does not occur There is no noticeable slip, noise or vibration

Manual Third

1. With the vehicle stopped, move the gear selector to THIRD.
2. Accelerate the vehicle to 64 km/h (40 mph).
3. Verify the following: The 1-2 shift occurs The 2-3 shift occurs There is no noticeable slip, noise or vibration

Torque Converter Diagnosis Procedure

The Torque Converter Clutch (TCC) is applied by fluid pressure, which is controlled by a PWM solenoid valve. This solenoid valve is located inside of the automatic transmission assembly. The solenoid valve is controlled through a combination of computer controlled switches and sensors.

Torque Converter Stator

The torque converter stator roller clutch can have two different malfunctions.

1. The stator assembly freewheels in both directions.
2. The stator assembly remains locked up at all times.

Poor Acceleration at Low Speed

If the stator is freewheeling at all times, the vehicle tends to have poor acceleration from a standstill. At speeds above 50-55 km/h (30-35 mph), the vehicle may act normally. For poor acceleration, you should first determine that the exhaust system is not blocked, and the transmission is in First gear when starting out.

If the engine freely accelerates to high RPM in NEUTRAL, you can assume that the engine and the exhaust system are normal. Check for poor performance in DRIVE and REVERSE to help determine if the stator is freewheeling at all times.

Poor Acceleration at High Speed

If the stator is locked up at all times, performance is normal when accelerating from a standstill. Engine RPM and vehicle speed are limited or restricted at high speeds. Visual examination of the converter may reveal a blue color from overheating.

If the converter has been removed, you can check the stator roller clutch by inserting a finger into the splined inner race of the roller clutch and trying to turn the race in both directions. You should be able to freely turn the inner race clockwise, but you should have difficulty in moving the inner race counterclockwise or you may be unable to move the race at all.

Noise

You may notice a torque converter whine when the vehicle is stopped and the transmission is in DRIVE or REVERSE. This noise will increase as you increase the engine RPM. The noise will stop when the vehicle is moving or when you apply the torque converter clutch, because both halves of the converter are turning at the same speed.

Perform a stall test to make sure the noise is actually coming from the converter

1. Place your foot on the brake.
2. Put the gear selector in DRIVE.
3. Depress the accelerator to approximately 1,200 RPM for no more than six seconds.

A torque converter noise will increase under this load.

Torque Converter Clutch Shudder

The key to diagnosing Torque Converter Clutch (TCC) shudder is to note when it happens and under what conditions.

TCC shudder which is caused by the transmission should only occur during the apply or the release of the converter clutch. Shudder should never occur after the TCC plate is fully applied.

If Shudder Occurs During TCC Apply or Release

If the shudder occurs while the TCC is applying, the problem can be within the transmission or the torque converter. Something is causing one of the following conditions to occur

1. Something is not allowing the clutch to become fully engaged.
2. Something is not allowing the clutch to release.
3. The clutch is releasing and applying at the same time.

One of the following conditions may be causing the problem to occur

1. Leaking turbine shaft seals
2. A restricted release orifice
3. A distorted clutch or housing surface due to long converter bolts
4. Defective friction material on the TCC plate

If Shudder Occurs After TCC has Applied

If shudder occurs after the TCC has applied, most of the time there is nothing wrong with the transmission.

The TCC is not likely to slip after the TCC has been applied. Engine problems may go unnoticed under light throttle and load, but they become noticeable after the TCC apply when going up a hill or accelerating. This is due to the mechanical coupling between the engine and the transmission.

Once TCC is applied, there is no torque converter (fluid coupling) assistance. Engine or driveline vibrations could be unnoticeable before TCC engagement.

Inspect the following components in order to avoid misdiagnosis of TCC shudder. An inspection will also avoid the unnecessary disassembly of a transmission or the unnecessary replacement of a torque converter.

1. Spark plugs - Inspect for cracks, high resistance or a broken insulator.
2. Plug wires - Look in each end. If there is red dust (ozone) or a black substance (carbon) present, then the wires are bad. Also look for a white discoloration of the wire. This indicates arcing during hard acceleration.
3. Coil - Look for a black discoloration on the bottom of the coil. This indicates arcing while the engine is misfiring.
4. Fuel injector - The filter may be plugged.
5. Vacuum leak - The engine will not get a correct amount of fuel. The mixture may run rich or lean depending on where the leak occurs.
6. EGR valve - The valve may let in too much or too little unburnable exhaust gas and could cause the engine to run rich or lean.
7. MAP/MAF sensor - Like a vacuum leak, the engine will not get the correct amount of fuel for proper engine operation.
8. Carbon on the intake valves - Carbon restricts the proper flow of air/fuel mixture into the cylinders.
9. Flat cam - Valves do not open enough to let the proper fuel/air mixture into the cylinders.
10. Oxygen sensor - This sensor may command the engine too rich or too lean for too long.
11. Fuel pressure - This may be too low.
12. Engine mounts - Vibration of the mounts can be multiplied by TCC engagement.
13. Axle joints - Check for vibration.
14. TP Sensor - The TCC apply and release depends on the TP Sensor in many engines. If the TP Sensor is out of specification, TCC may remain applied during initial engine loading.
15. Cylinder balance - Bad piston rings or poorly sealing valves can cause low power in a cylinder.
16. Fuel contamination - This causes poor engine performance.

Replace the torque converter if any of the following conditions exist

1. External leaks appear in the hub weld area.
2. The converter hub is scored or damaged.
3. The converter pilot is broken, damaged, or fits poorly into the crankshaft.
4. You discover steel particles after flushing the cooler and the cooler lines.
5. The pump is damaged, or you discover steel particles in the converter.
6. The vehicle has TCC shudder and/or no TCC apply. Replace the torque converter only after all hydraulic and electrical diagnoses have been made. The converter clutch material may be glazed.
7. The converter has an imbalance which cannot be corrected. Refer to «Flexplate/Torque Converter Vibration Test»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l60-e4l65-e-troubleshooting) .
8. The converter is contaminated with engine coolant which contains antifreeze or water.
9. An internal failure occurs in the stator roller clutch.
10. You notice excessive end play.
11. Overheating produces heavy debris in the clutch or converter ballooning.
12. You discover steel particles or clutch lining material in the fluid filter or on the magnet, when no internal parts in the unit are worn or damaged. This condition indicates that lining material came from the converter.

Do not replace the torque converter if you discover any of the following symptoms

1. The oil has an odor or the oil is discolored, even though metal or clutch facing particles are not present.
2. The threads in one or more of the converter bolt holds are damaged. Correct the condition with a new thread inset.
3. Transmission failure did not display evidence of damaged or worn internal parts, steel particles or clutch plate lining material in the unit and inside the fluid filter.
4. The vehicle has been exposed to high mileage only. An exception may exist where the lining of the torque converter clutch dampener plate has seen excess wear by vehicles operated in heavy and/or constant traffic, such as taxi, delivery, or police use.

Isolating Vibration

Note. Some engine/transaxle combinations cannot be balanced in this manner due to restricted access or limited clearances between the torque converter bolts and the engine. Ensure that the bolts do not bottom out in the lug nuts or the torque converter cover could be dented and cause internal damage.

To isolate and correct a flywheel or torque converter vibration, separate the torque converter from the flywheel to determine if vibration is in the engine or transmission.

1. With the engine at idle speed and the transmission in PARK or NEUTRAL, observe the vibration.
2. Turn the engine OFF.
3. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-g3500/1996-2012/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
4. Remove the transmission converter cover bolts and the cover.
5. Mark the relationship of the converter to the flywheel.
6. Remove the bolts attaching the converter to the flywheel.
7. Slide the torque converter away from the flywheel.
8. Rotate the flywheel and torque converter to inspect for defects or missing balance weights. Refer to «Engine Flywheel Cleaning and Inspection»(/chevrolet/chevy-express-g3500/1996-2012/remont/mechanical/#engine-mechanical-43l) in Engine Mechanical - 4.3L or «Engine Flywheel Cleaning and Inspection»(/chevrolet/chevy-express-g3500/1996-2012/remont/mechanical/#engine-mechanical-removal-installation-2-of-3-48l-53l-60l__engine-flywheel-cleaning-and-inspection) in Engine Mechanical 4.8L, 5.3L and 6.0L.
9. Lower the vehicle.
10. With the engine at idle speed and the transmission in PARK or NEUTRAL, observe the vibration. Refer to «Diagnostic Starting Point - Vibration Diagnosis and Correction»(/chevrolet/chevy-express-g3500/1996-2012/remont/oem-general-information/#vibration-symptoms-diagnosis-and-correction__diagnostic-starting-point-vibration-diagnosis) in Vibration Diagnosis and Correction.
11. Turn the engine OFF.

Indexing Torque Converter

To determine and correct a torque converter vibration, the following procedure may have to be performed several times to achieve the best possible torque converter to flywheel balance.

1. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-g3500/1996-2012/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
2. Rotate the torque converter one bolt position.
3. Align the torque converter hub (2) in the engine crankshaft (3) and install the torque converter to flywheel bolts.
4. Lower the vehicle.
5. With the engine at idle speed and the transmission in PARK or NEUTRAL, observe the vibration. Refer to «Noise and Vibration Analysis»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l60-e4l65-e-troubleshooting__noise-and-vibration-analysis) . Repeat this procedure until you obtain the best possible balance.
6. Install the transmission converter cover bolts and the cover.

Noise and Vibration Analysis

A noise or vibration that is noticeable when the vehicle is in motion MAY NOT be the result of the transmission.

If noise or vibration is noticeable in PARK and NEUTRAL with the engine at idle, but is less noticeable as RPM increases, the cause may be from poor engine performance.

1. Vibration may also be caused by a small amount of water inside the converter.
2. Inspect the tires for the following conditions: Uneven wear Imbalance Mixed sizes Mixed radial and bias ply
3. Inspect the suspension components for the following conditions: Alignment and wear Loose fasteners Driveline damage or wear
4. Inspect the engine and transmission mounts for damage and loose bolts.
5. Inspect the transmission case mounting holes for the following conditions: Missing bolts, nuts, and studs Stripped threads Cracks
6. Inspect the flywheel for the following conditions: Missing or loose bolts Cracks Imbalance
7. Inspect the torque converter for the following conditions: Missing or loose bolts or lugs Missing or loose balance weights Imbalance caused by heat distortion or fluid contamination

Composition Plates

Dry the plates and inspect the plates for the following conditions

1. Pitting
2. Flaking
3. Delamination - splitting or separation of bonded clutch material
4. Wear
5. Glazing
6. Cracking
7. Charring
8. Chips or metal particles embedded in the lining

Replace a composition plate which shows any of these conditions.

Steel Plates

Wipe the plates dry and check the plates for heat discoloration. If the surfaces are smooth, even if color smear is indicated, you can reuse the plate. If the plate is discolored with heat spots or if the surface is scuffed, replace the plate.

Causes of Burned Clutch Plates

The following conditions can result in a burned clutch plate

1. Incorrect usage of clutch or apply plates
2. Engine coolant or water in the transmission fluid
3. A cracked clutch piston
4. Damaged or missing seals
5. Low line pressure
6. Valve body conditions The valve body face is not flat. Porosity is between channels. The valve bushing clips are improperly installed. The checkballs are misplaced.
7. The Teflon® seal rings are worn or damaged.

Engine Coolant/Water in Transmission

Note. The antifreeze or water will deteriorate the seals, gaskets and the glue that bonds the clutch material to the pressure plate. Both conditions may cause damage to the transmission.

If antifreeze or water has entered the transmission, perform the following

1. Disassemble the transmission.
2. Replace all of the rubber type seals (the coolant will attack the seal material which will cause leakage).
3. Replace the composition-faced clutch plate assemblies (the facing material may separate from the steel center portion).
4. Replace all of the nylon parts (washers).
5. Replace the torque converter.
6. Thoroughly clean and rebuild the transmission, using new gaskets and oil filter.
7. Flush the cooler lines after the transmission cooler has been properly repaired or replaced.

General Method

1. Verify that the leak is transmission fluid.
2. Thoroughly clean the suspected leak area.
3. Operate the vehicle for 24 km (15 mi), or until normal operating temperatures are reached.
4. Park the vehicle over clean paper or cardboard.
5. Shut OFF the engine.
6. Look for fluid spots on the paper.
7. Make the necessary repairs.

Powder Method

1. Thoroughly clean the suspected leak area with solvent.
2. Apply an aerosol type powder, such as foot powder, to the suspected leak area.
3. Operate the vehicle for 24 km (15 mi), or until normal operating temperatures are reached.
4. Shut OFF the engine.
5. Inspect the suspected leak area.
6. Trace the leak path through the powder in order to find the source of the leak.
7. Make the necessary repairs.

Dye and Black Light Method

A fluid dye and black light kit is available from various tool manufacturers.

1. Follow the manufacturer's instructions in order to determine the amount of dye to use.
2. Detect the leak with the black light.
3. Make the necessary repairs.

Find the Cause of the Leak

Pinpoint the leak and trace the leak back to the source. You must determine the cause of the leak in order to repair the leak properly. For example, if you replace a gasket, but the sealing flange is bent, the new gasket will not repair the leak. You must also repair the bent flange. Before you attempt to repair a leak, check for the following conditions, and make repairs as necessary

Gaskets

1. Fluid level/pressure is too high
2. Plugged vent or drain-back holes
3. Improperly tightened fasteners
4. Dirty or damaged threads
5. Warped flanges or sealing surface
6. Scratches, burrs, or other damage to the sealing surface
7. Damaged or worn gasket
8. Cracking or porosity of the component
9. Improper sealant used, where applicable
10. Incorrect gasket

Seals

1. Fluid level/pressure is too high
2. Plugged vent or drain-back holes
3. Damaged seal bore
4. Damaged or worn seal
5. Improper installation
6. Cracks in component
7. Manual or output shaft surface is scratched, nicked, or damaged
8. Loose or worn bearing causing excess seal wear

Possible Points of Fluid Leaks

Transmission Oil Pan

1. Incorrectly tightened oil pan bolts
2. Improperly installed or damaged oil pan gasket
3. Damaged oil pan or mounting face
4. Incorrect oil pan gasket

Case Leak

1. Damaged or missing fill tube seal
2. Mislocated fill tube bracket
3. Damaged vehicle speed sensor seal
4. Damaged manual shaft seal
5. Loose or damaged oil cooler connector fittings
6. Worn or damaged propeller shaft oil seal
7. Loose line pressure pipe plug
8. Porous casting warped torque converter housing

Leak at the Torque Converter End

1. Converter leak in the weld area
2. Converter seal lip cut. Check the converter hub for damage
3. Converter seal bushing moved forward and damaged
4. Converter seal garter spring missing from the seal
5. Porous casting of the transmission case or the oil pump

Leak at the Vent Pipe or the Fluid Fill Tube

1. Overfilled system
2. Water or coolant in the fluid. The fluid will appear milky
3. Transmission case porous
4. Incorrect fluid level indicator
5. Plugged vent
6. Drain-back holes plugged
7. Mispositioned oil pump to case gasket, if equipped

Scheme 173

Case Porosity Repair

Some external leaks are caused by case porosity in non-pressurized areas. You can usually repair these leaks with the transmission in the vehicle.

1. Thoroughly clean the area to be repaired with a cleaning solvent. Air dry the area.
2. Using instructions from the manufacturer, mix a sufficient amount of an epoxy to make the repair.
3. While the transmission case is still hot, apply the epoxy. You can use a clean, dry soldering acid brush to clean the area and also to apply the epoxy cement. Make certain that the area to be repaired is fully covered.
4. Allow the epoxy cement to cure for three hours before starting the engine.
5. Repeat the fluid leak diagnosis procedures.

Shift Solenoid Leak Test

Tools Required

1. J 35616 GM Terminal Test Kit
2. J 44246 Solenoid Testing Kit

Leak Test Procedure

1. Remove the shift solenoid valve from the control valve body or the torque converter clutch (TCC) solenoid valve from the transmission case. Refer to «Control and Shift Solenoids Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l60-e4l65-e-introduction-service-replacement) or «Torque Converter Clutch Pulse Width Modulation (TCC PWM) Solenoid, TCC Solenoid, and Wiring Harness»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l60-e4l65-e-introduction-service-replacement) .
2. Install the TCC solenoid valve, the 1-2 shift solenoid valve or the 2-3 shift solenoid valve into bore number 2 of the J 44246 and install the factory retainer clip to retain the solenoid.
3. Connect the solenoid testing harness supplied with the J 44246 to the solenoid.
4. Apply compressed air to the J 44246 .
5. Air should flow through the solenoid. If air does not flow through the solenoid, replace the solenoid. Refer to «Control and Shift Solenoids Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l60-e4l65-e-introduction-service-replacement) .
6. Connect the solenoid testing harness to the 12-volt positive (+) and negative (-) battery terminals.
7. Observe if the solenoid is operating electrically. An audible clicking noise can be heard when connecting or disconnecting power.
8. Observe the air flow through the solenoid. The flow will completely or nearly completely stop. Replace the solenoid if there continues to be an obvious air leak when the solenoid is energized.
9. Install the shift solenoid valve into the control valve body or the TCC solenoid valve into the transmission case. Refer to «Control and Shift Solenoids Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l60-e4l65-e-introduction-service-replacement) or «Torque Converter Clutch Pulse Width Modulation (TCC PWM) Solenoid, TCC Solenoid, and Wiring Harness»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l60-e4l65-e-introduction-service-replacement) .

Automatic Transmission Oil Cooler Flushing and Flow Test (J 45096)

GM studies indicate that plugged or restricted transmission oil coolers and pipes cause insufficient transmission lubrication and elevated operating temperatures which can lead to premature transmission failure. Many repeat repair cases could have been prevented by following published procedures for transmission oil cooler flushing and flow checking. This procedure includes flow checking and flushing the auxiliary transmission oil cooler, if equipped.

Only GM Goodwrench DEXRON®III automatic transmission fluid should be used when doing a repair on a GM transmission.

Time allowance for performing the cooler flow checking and flushing procedure has been included in the appropriate labor time guide operations since the 1987 model year. The service procedure steps for oil cooler flushing and flow testing are as follows

Cooler Flow Check and Flushing Steps

1. Machine Set-up
2. Determine Minimum Flow Rate
3. Back Flush
4. Forward Flush
5. Flow Test
6. Code Recording Procedure
7. Clean-up

Tools Required

1. J 35944-200 Cooler Flushing Adapter
2. J 45096 Transmission Oil Cooling System Flush and Flow Test Tool
3. Shop air supply with water/oil filters, regulator and pressure gage - minimum 90 psi
4. Eye protection
5. Rubber gloves

Scheme 174

1. Verify that the main power switch (1) is in the OFF position.
2. Place the main function switch (2) in the IDLE position.
3. Connect J 45096 to the vehicle 12-volt DC power source by connecting the red battery clip to the positive (+) battery post on the vehicle and connect the negative (-) lead to a known good chassis ground.
4. Turn the main power switch to the ON position.
5. Fill the supply tank with Dexron®III/Mercon®, or equivalent, through the fill port.
6. Install and tighten the fill cap.
7. Connect a shop air supply hose to the quick-disconnect on the rear panel marked SUPPLY AIR.

Determine Minimum Flow Rate

1. From the machine display, identify the temperature of the automatic transmission fluid that is stored in the supply vessel of J 45096 .
2. Determine whether the transmission oil cooler is steel or aluminum by using a magnet (1) at the cooler flange (2) at the radiator.
3. Refer to the table below. Using the temperature from step 1, locate on either the Steel MINIMUM Flow Rate table or the Aluminum MINIMUM Flow Rate table the minimum flow rate in gallons per minutes (GPM). Record the minimum flow rate in GPMs and the supply fluid temperature for further reference. Example: Fluid temperature: 24°C (75°F) Cooler type: Steel The MINIMUM flow rate for this example would be 0.8 GPM.
4. Inspect transmission oil cooler lines for damage or kinks that could cause restricted oil flow. Repair as needed and refer to the appropriate GM service manual procedures.

Minimum Flow Rate in Gallons Per Minute (GPM)

Scheme 175

1. Connect the J 45096 adapters (1) to the vehicle's transmission oil cooler supply and return lines at the transmission, may require J 35944-200 .
2. Connect the black supply hose (1) to the return line, top connector of the transmission, and the clear waste hose (2) to the feed line, bottom connector of the transmission, to the vehicle cooler lines. This is the reverse flow-backflush direction.
3. Turn the main function switch to the FLUSH position. Allow the machine to operate for 30 seconds.
4. Turn the main function switch to the IDLE position and allow the supply vessel pressure to dissipate.

Forward Flush

1. Disconnect the supply and waste hoses from the vehicle cooler lines. Reverse the supply and waste hoses to provide a normal flow direction.
2. Turn the main function switch to the FLUSH position and allow the machine to operate for 30 seconds.

Flow Test

1. Turn the main function switch to the FLOW position and allow the oil to flow for 15 seconds. Observe and note the flow rate. This is the TESTED flow rate.
2. Compare the TESTED flow rate to the MINIMUM flow rate information previously recorded. If the TESTED flow rate is equal to or greater than the MINIMUM flow rate recorded, the oil cooling system is functioning properly. Perform Code Recording Procedure. If the TESTED flow rate is less than the MINIMUM flow rate previously recorded, repeat the back flush and forward flush procedures.
3. If the TESTED flow rate is less than the MINIMUM flow rate after the second test, perform the Code Recording Procedure. Replace the transmission oil cooler. Connect the supply and waste hoses to the cooler lines in the normal flow direction. Perform the Flow Test. Perform the Code Recording Procedure.

Code Recording Procedure

1. Turn the main function switch to the CODE position.
2. Record TESTED flow rate, temperature, cycle and seven-character flow code information on the repair order.

Clean-Up

1. Turn the main function switch to the IDLE position and allow the supply vessel pressure to dissipate.
2. Turn the main power switch to the OFF position.
3. Disconnect the supply and waste hoses and the 12-volt power source from the vehicle.
4. Disconnect the air supply hose from J 45096 .
5. Dispose of the waste ATF in accordance with all applicable federal, state, and local requirements.

Automatic Transmission Oil Cooler Flushing and Flow Test (J 35944-A)

GM studies indicate that plugged or restricted transmission oil coolers and pipes cause insufficient transmission lubrication and elevated operating temperatures which can lead to premature transmission wear-out. Many repeat repair cases could have been prevented by following published procedures for transmission oil cooler flushing and flow checking. This procedure includes flow checking and flushing the auxiliary transmission oil cooler, if equipped.

Only GM Goodwrench DEXRON®III automatic transmission fluid should be used when doing a repair on a GM transmission.

Time allowance for performing the cooler flow checking and flushing procedure has been included in the appropriate labor time guide operations since the 1987 model year. The service procedure steps for oil cooler flushing are as follows

Cooler Flow Check and Flushing Steps

1. Tools Required
2. Preparation
3. Back Flush
4. Forward Flush
5. Flow Check
6. Clean-up

Tools Required

1. J 35944-A Transmission Oil Cooler Flusher
2. J 35944-22 Transmission Oil Cooler Flushing Fluid
3. J 35944-200 Cooler Flushing Adapter
4. Measuring cup
5. Funnel
6. Water supply, hot water recommended
7. Water hose, at least 16 mm (5/8 in) ID
8. Shop air supply, with water/oil filters, regulator and pressure gage
9. Air chuck, with clip if available
10. Oil drain container
11. Pail with lid 19 L (5 gallon)
12. Eye protection
13. Rubber gloves

Preparation

1. During the installation of the repaired or replacement transmission, do not connect the oil cooler pipes.
2. Remove the fill cap (9) on the J 35944-A and fill the flusher tank (4) with 0.6 L (20-21 oz) of J 35944-22 , using the measuring cup (6). Do not overfill.
3. Install the fill cap (9) on the J 35944-A and pressurize the flusher tank (4) to 550-700 kPa (80-100 psi), using the shop air supply at the tank air valve (2).
4. With the water supply valve (1) on the J 35944-A in the OFF position, connect the water supply hose from the J 35944-A to the water supply at the faucet.
5. Turn ON the water supply at the faucet.

Back Flush

1. Inspect the transmission oil cooler pipes for kinks or damage. Repair as necessary.
2. Connect the J 35944-A to the oil cooler feed bottom connector. Use the J 35944-200 , if required.
3. Clip the discharge hose (2) onto the oil drain container.
4. Attach the J 35944-A to the undercarriage of the vehicle with the hook provided and connect the flushing system feed supply hose (1) from the J 35944-A to the top connector oil cooler return pipe. Use the J 35944-200 , if required.
5. Turn the J 35944-A water supply valve (3) to the ON position and allow water to flow through the oil cooler and pipes for 10 seconds to remove any remaining transmission fluid. If water does not flow through the oil cooler and pipes, the cause of the blockage must be diagnosed and the plugged component must be repaired or replaced. Continue with the cooler flushing and flow check procedure once the blockage is corrected.
6. Turn the J 35944-A water supply valve (3) to the OFF position and clip the discharge hose onto a 19 liter (5 gallon) pail with a lid, to avoid splashback.
7. Turn the J 35944-A water supply valve (3) to the ON position and depress the trigger (1) to mix cooler flushing solution into the water flow. Use the clip provided on the handle to hold the trigger (1) down. The discharge will foam vigorously when the solution is introduced into the water stream.
8. Flush the oil cooler and pipes with water and solution for 2 minutes. During this flush, attach the shop air supply 825 kPa (120 psi) to the flushing system feed air valve (2) located on the J 35944-A , for 3-5 seconds at the end of every 15-20 second interval to create a surging action.
9. Release the trigger (1) and turn the J 35944-A water supply valve (3) to the OFF position.

1. Disconnect both hoses (1 and 2) from the oil cooler pipes and connect them to the opposite oil cooler pipe. This will allow the oil cooler and pipes to be flushed in the normal flow direction.
2. Repeat Step 6 and 7 of the Back Flush.
3. Release the trigger (1) of the J 35944-A and allow water only to rinse the oil cooler and pipes for 1 minute.
4. Turn the J 35944-A water supply valve (3) to the OFF position and turn OFF the water supply at the faucet.
5. Attach the shop air supply to the flushing system feed air valve (2) on the J 35944-A and blow out the water from the oil cooler and pipes. Continue, until no water comes out of the discharge hose.

Scheme 176

1. Disconnect the hose from the oil cooler pipe. Connect the oil cooler feed pipe, bottom connector, to the transmission for normal flow. IMPORTANT: The Flow Test must be performed after the flush to ensure that all flushing solution and water is removed from the oil cooling system.
2. Clip the discharge hose (1) to an empty oil container.
3. Confirm the transmission is filled with automatic transmission fluid. Refer to «Fluid Capacity Specifications»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l60-e4l65-e-introduction-service-replacement__fluid-capacity-specifications) for the correct automatic transmission fluid capacity.
4. Start the engine with the transmission in PARK range and run for 30 seconds after fluid begins to flow from the discharge hose (1). A minimum of 1.9 L (2 qt) must be discharged during this 30 second run time.
5. If the fluid flow meets or exceeds 1.9 L (2 quarts) in 30 seconds, connect the oil cooler feed pipe to the bottom connector on the transmission.
6. If fluid flow is less than 1.9 L (2 qt) in 30 seconds, perform the following diagnosis: Disconnect the J 35944-A discharge hose (1) from the oil cooler return pipe. Disconnect the oil cooler feed pipe at the radiator. Connect the J 35944-A discharge hose (1) to the oil cooler feed pipe, radiator end. Clip the discharge hose (1) onto the oil drain container. Start the engine with the transmission in PARK range and run for 30 seconds after fluid begins to flow from the discharge hose (1). A minimum of 1.9 L (2 qt) must be discharged during this 30 second run time.
7. If the amount of transmission fluid flow remains less than 1.9 L (2 qt) in 30 seconds, inspect the oil cooler feed pipe, bottom connector, for restrictions or damage. If no condition is found with the feed pipe, bottom connector, inspect the transmission.

1. Disconnect the water supply hose from the J 35944-A and bleed any remaining air pressure from the flusher tank.
2. Remove the fill cap from the J 35944-A and return any unused flushing solution to its container. Rinse the J 35944-A with water. Do not store the J 35944-A with flushing solution in it.
3. After every third use, clean the J 35944-A as described in the instructions included with the tool.
4. Dispose of any waste water/solution and transmission fluid in accordance with local regulations.

Transmission Overheats

Transmission Overheats

Oil Pressure High or Low

Oil Pressure High or Low

Harsh Shifts

Harsh Shifts

Inaccurate Shift Points

Inaccurate Shift Points

First Gear Range Only - No Upshift

1st Gear Range Only - No Upshift

Slips in First Gear

Slips in 1st Gear

Slipping or Harsh 1-2 Shift

Slipping or Rough 1-2 Shift

No 2-3 Shift or 2-3 Shift Slips, Rough or Hunting

No 2-3 Shift or 2-3 Shift slipping, Rough or Hunting

Second/Third Gear Only or First/Fourth Gears Only

Second/Third Gears Only or First/Fourth Gears Only

No First or Second Gear/No Third or Fourth Gear

No 1st or 2nd/No 3rd or 4th

No Second Gear, No Fourth Gear, and No Reverse Gear

No Second Gear, No Fourth Gear and No Reverse Gear

Third Gear Only

Third Gear Only

3-2 Flare or Tie-Up

3-2 Flare or Tie-Up

No 3-4 Shift, Slips or Rough 3-4 Shift

No 3-4 Shift/Slipping or Rough 3-4 Shift

No Reverse or Slips in Reverse

No Reverse or Slips in Reverse

No Part Throttle or Delayed Downshifts

No Part Throttle or Delayed Downshifts

Harsh Garage Shift

Harsh Garage Shift

No Overrun Braking - Manual 3-2-1

No Overrun Braking - Manual 3-2-1

No Torque Converter Clutch (TCC) Apply (300 RPM Slip)

No Torque Converter Clutch (TCC) Apply

Torque Converter Clutch (TCC) Shudder

No Torque Converter Clutch Shudder

No Torque Converter Clutch (TCC) Release

No TCC Release

Torque Converter Clutch (TCC) Slip - 100 RPM Slip

TCC Slip (100 RPM)

Torque Converter Clutch (TCC) Slip with Stall/Stumble

TCC Slip with Stall/Stumble

Torque Converter Clutch (TCC) Intermittent - OK Cold/Slips Hot

Intermittent TCC OK Cold/Slips Hot

No Fourth Gear, or Slips in Fourth Gear

No 4th or Slipping 4th

Slip/Flare in Any Gear

Slip/Flare in any Gear

No Third Gear

No 3rd

Drives in Neutral

Drives in Neutral

Second Gear Start

Second Gear Start

No Park

No Park

Oil Out the Vent

Oil Out the Vent

Vibration in Reverse and Whining Noise in Park

Vibration in Reverse and Whining Noise in Park

Ratcheting Noise

Ratcheting Noise

Popping Noise

Popping Noise

Whine Noise Varying with RPM or Fluid Pressure

Whine Noise Varying with RPM or Fluid Pressure

Buzz Noise or High Frequency Rattle Sound

Buzz Noise or High Frequency Rattle Sound

Noise in Random Ranges

Noise in Random Ranges

No Drive in All Ranges

No Drive in All Ranges

No Drive in Drive Range

No Drive in Drive Range

Shift Lever Indicates Wrong Gear

Shift Lever Indicates Wrong Gear

No Gear Selection

No Gear Selection

Engine Starts in Gear

Engine Starts in Gear

Delay in Drive and Reverse

Delay in Drive and Reverse

Lack of Power or Hesitation

Lack of Power or Hesitation

See also:
• Transmission Range Switch Logic
• Intermittent Conditions
• Intermittent Conditions
• Testing for Continuity
• Wiring Repairs
• Circuit Testing
• Park/Neutral Position Switch Replacement
• Powertrain Control Module (PCM) Replacement
• Instrument Panel Cluster (IPC) Replacement
• Diagnostic Starting Point - Body Control System
• Line Pressure
• Fastener Notice
• Scan Tool Data List
• Shift Speed
• Lifting and Jacking the Vehicle
• Engine Flywheel Cleaning and Inspection
• Engine Flywheel Cleaning and Inspection
• Diagnostic Starting Point - Vibration Diagnosis and Correction
• Automatic Transmission Inline 20-Way Connector End View
• Fluid Capacity Specifications
• Range Reference
• Transmission Fluid Pressure (TFP) Manual Valve Position Switch Logic
• Transmission Fluid Checking Procedure
• Oil Pressure High or Low
• Fluid Leak Diagnosis
• Oil Out the Vent
• Ratcheting Noise
• Vibration in Reverse and Whining Noise in Park
• Popping Noise
• Whine Noise Varying with RPM or Fluid Pressure
• Buzz Noise or High Frequency Rattle Sound
• Noise in Random Ranges
• Drives in Neutral
• No Park
• No Reverse or Slips in Reverse
• No Drive in All Ranges
• No Drive in Drive Range
• No Overrun Braking - Manual 3-2-1
• Lack of Power or Hesitation
• Harsh Shifts
• Slipping or Harsh 1-2 Shift
• No 2-3 Shift or 2-3 Shift Slips, Rough or Hunting
• No 3-4 Shift, Slips or Rough 3-4 Shift
• Harsh Garage Shift
• Delay in Drive and Reverse
• 3-2 Flare or Tie-Up
• First Gear Range Only - No Upshift
• Third Gear Only
• Second/Third Gear Only or First/Fourth Gears Only
• Slips in First Gear
• No Part Throttle or Delayed Downshifts
• Second Gear Start
• Inaccurate Shift Points
• Torque Converter Diagnosis Procedure
• No Torque Converter Clutch (TCC) Apply (300 RPM Slip)
• No Torque Converter Clutch (TCC) Release
• Torque Converter Clutch (TCC) Shudder
• Road Test Procedure
• Line Pressure Check Procedure
• Symptoms - Automatic Transmission
• Automatic Transmission Oil Cooler Flushing and Flow Test (J 45096)
• Noise and Vibration Analysis