Circuit Test D24

This test should be performed ONLY if a problem has been detected in transaxle. If any of these service codes appeared during SELF-TEST, the AXOD DRIVE CYCLE TEST should be performed. A jumper harness is used to connect to the transmission bulkhead connector and test electrical circuits. The following AXOD transaxle related items have malfunctioned or failed as indicated:

Code 39: Transaxle converter by-pass clutch is not operating properly.
Code 59, 62, 68 and 69: Refer to CIRCUIT TEST D21 for summary of these codes.
Code 89: Transaxle converter by-pass clutch solenoid has stayed always open or closed.

The following service codes are not AXOD transaxle related, but can affect converter clutch by-pass operation. Service these components before servicing AXOD transaxle codes:

Code 21: Engine Coolant Temperature (ECT) sensor out of range.
Code 22: Manifold Absolute Pressure (MAP) sensor out of range.
Code 23: Throttle Position Sensor (TPS) out of range.
Code 24: Air Charge Temperature (ACT) sensor out of range.
Code 29: Vehicle Speed Sensor (VSS) not functioning.
Code 74: Brake ON/OFF (BOO) switch always open or brake not applied during KOER SELF-TEST.
Code 75: Brake ON/OFF (BOO) switch always closed.

The following service code indicates that a transaxle component may have caused faulty engine idle speed control:

Code 57: Neutral Pressure Switch (NPS) failed in Neutral (open) position. The NPS is normally open and closes with hydraulic pressure. Failure of transaxle to engage in "D" or "R" will cause Code 57 to be displayed. Check for proper hydraulic pressure before testing AXOD transaxle electrical components.
Code 67: Neutral Pressure Switch (NPS) failed closed.
NOTE: Ensure that all components are connected before performing test. Perform AXOD DRIVE CYCLE TEST on a slight upgrade or flat terrain. If any other non-AXOD related codes appear, service those codes first as they could affect electrical operation of transaxle.

NOTE: All components must be connected for this test and the following AXOD DRIVE CYCLE TEST must be performed:
Record and clear Continuous Memory Codes.
Warm engine to operating temperature.
With transaxle in "D" range, lightly accelerate from a stop to 40 MPH to allow transaxle to shift into 3rd gear. Hold speed and throttle opening steady for a minimum of 15 seconds (30 seconds above 4000 feet altitude).
Shift transaxle into overdrive and accelerate lightly from 40 to 50 MPH to allow transaxle to shift into 4th gear. Hold speed and throttle opening steady, in 4th gear, for a minimum of 15 seconds.
With transaxle in 4th gear, throttle open and speed steady, lightly apply and release brakes (enough to turn on brake lights). Hold speed and throttle opening steady for an additional 15 seconds.
Brake to a stop and remain stopped for a minimum of 20 seconds with transaxle in overdrive range. Perform KOEO SELF-TEST and record Continuous Memory Codes.

Fig 1: Jumper Harness

Fig 2: Transmission Component Locations

Continuous Memory Code 39: Faulty Converter By-Pass Clutch (CBC), Check Harness Connections. Check that vehicle harness connector is fully attached to transaxle bulkhead connector and that vehicle harness connector terminals are fully seated in connector. If connector or terminals are not okay, repair as required and repeat QUICK TEST. If connector and terminals are okay, go to next step.
Checking Solenoid Resistance. Install jumper harness to transaxle bulkhead connector. Connect VOM positive test lead to Red wire and negative test lead to Black wire. Check resistance. If reading is between 20 and 40 ohms, go to QUICK TEST and service codes as required. If reading is not between 20 and 40 ohms, go to next step.
Check By-Pass Clutch Application. Connect jumper harness Red wire to battery positive post. With engine running and transaxle in 3rd gear, connect jumper harness Black wire to ground (to energize by-pass clutch solenoid). DO NOT connect with polarity reversed, otherwise solenoid diode will be damaged. If by-pass clutch is applied (engine RPM drops slightly), there is no electrical component failure. By-pass clutch is operating properly. Error code may be indicating a slipping by-pass clutch. Service transaxle for a no converter clutch apply condition and repeat QUICK TEST. If by-pass clutch is not applied (engine RPM does not drop), go to next step.
Check By-Pass Solenoid Valve. Check main control by-pass clutch control valve (in valve body) for sticking. If valve is sticking, service spool valve as necessary. If valve is okay, go to next step.
Check By-Pass Solenoid. Remove by-pass solenoid. Check condition of "O" ring. Also check for contamination in/on solenoid or small hole in valve. Shake solenoid vigorously to check for free armature. If solenoid is faulty, replace by-pass clutch solenoid and repeat QUICK TEST. If solenoid is okay, service transaxle for a no converter clutch apply condition and repeat QUICK TEST.
NOTE: The THS 4/3 and 3/2 pressure switches are normally open and close with hydraulic pressure. Failure of transaxle to engage in "D" will cause Code 59 to be displayed. Failure of transaxle to shift into 3rd gear will cause Code 69 to be displayed. Check for proper hydraulic operation before testing electrical components.
Code 59: THS 4/3 Switch Failed to Open, Check Wiring. Check that vehicle harness connector is fully engaged in transaxle bulkhead connector and that vehicle harness connector terminals are fully seated in connector. If connector or terminals are not okay, repair as required and repeat QUICK TEST. If connector and terminals are okay, go to next step.
Check Switch For Continuity. Install jumper harness to transaxle bulkhead connector. Using VOM, check for continuity between engine ground and Blue wire. With engine running and transaxle in Neutral, VOM should indicate no continuity (infinite resistance). Shift transaxle into "D". Switch should close and resistance should be less than 10 ohms. Switch should stay closed in 1st, 2nd and 3rd gears, and then open in 4th gear. If circuit is okay, go to QUICK TEST and service codes as required. If circuit is not okay, go to next step.
Checking Internal Connections. Remove transaxle side oil pan. Check that internal connector with Blue wire is firmly attached to THS 4/3 pressure switch. Connector should not pull off easily or fit loosely. If connector is not okay, replace bulkhead connector and wiring assembly. Repeat QUICK TEST. If connector is okay, go to next step.
Check Internal Wiring. Remove connector from pressure switch by pushing on end of connector, while pulling on wire end of connector. Check for continuity in bulkhead connector by measuring resistance between Blue wire and terminal inside connector just removed. If reading is more than 2 ohms, replace bulkhead connector and wiring assembly. Repeat QUICK TEST. If reading is less than 2 ohms, go to next step.
Check THS 4/3 Switch. Remove THS 4/3 pressure switch. Install a 1/8-27 pipe fitting that can be connected to LOW pressure air supply in order to pressure test leaks and switch closure. With 50 psi (3.5 kg/cm² ) applied, check for ruptured diaphragm by submerging switch in clean transmission fluid. NEVER check in water. Check for bubbles coming out of small vent hole near switch terminal. If bubbles show, diaphragm has failed. Replace THS 4/3 pressure switch and repeat QUICK TEST. If no bubbles show, go to next step.
Check Switch Resistance. With 50 psi (3.5 kg/cm² ) applied to switch, check resistance between switch terminal and switch case. If reading is less than 8 ohms, hydraulic pressure circuit to switch may have excessive leaks. Service transaxle as required. If reading is more than 8 ohms, replace switch. Repeat step 8), and then QUICK TEST. Codes 39, 59, 62, 69 and 89 should no longer be displayed.
NOTE: If Code 62 appears in KOEO SELF-TEST, THS 3/2 circuit has failed. If Code 62 appears in KOER SELF-TEST, THS 4/3 circuit has failed. If Code 62 appears in both SELF-TESTS, follow entire test procedure to determine which circuit has failed.
Code 62. Remove vehicle harness connector from transaxle bulkhead connector and install jumper harness. Using DVOM, measure continuity between engine ground and White wire (THS 3/2 circuit). With engine off, DVOM should indicate no continuity (infinite resistance). Measure continuity between engine ground and Blue wire (THS 4/3 circuit). With engine running and transaxle in Neutral, VOM should indicate no continuity (infinite resistance). If all readings show no continuity, go to QUICK TEST and service codes as required. If any reading indicates continuity, go to next step.
Check Internal Wiring. Remove transaxle side oil pan. Check for pinched, cut, or otherwise grounded wiring. If wiring is damaged, replace bulkhead connector and wiring assembly. After repairs, repeat QUICK TEST. If THS 4/3 pressure switch wiring is okay, go to step 15). If THS 3/2 pressure switch wiring is okay, go to next step.
Checking 3/2 Switch. Remove wiring from THS 3/2 pressure switch. Using DVOM, check pressure switch for continuity to engine ground by connecting one lead to switch terminal and other lead to valve body. If there is no continuity (infinite resistance), go to step 16). If there is continuity to ground, replace THS 3/2 pressure switch and repeat QUICK TEST.
Check 4/3 Switch. Remove wiring from THS 4/3 pressure switch. Using DVOM, check pressure switch for continuity to engine ground by connecting one lead to switch terminal and other lead to valve body. If there is continuity to ground, replace 4/3 pressure switch and repeat QUICK TEST. If there is no continuity (infinite resistance), go to next step.
Check Internal Wires. Using DVOM and with wiring removed from both pressure switches, check continuity to ground. Connect one test lead to White wire and other test lead to ground. Connect one test lead to Blue wire and other test lead to ground. Ensure internal terminals are not touching any metallic parts. If there is continuity to ground, replace bulkhead connector and wiring assembly. Repeat QUICK TEST. If there is no continuity (infinite resistance), go to QUICK TEST and service codes as required.
NOTE: The THS 4/3 and 3/2 pressure switches are normally open switches that close with hydraulic pressure. Failure of transaxle to engage in "D" will cause service Code 59 to be displayed. Failure of transaxle to shift into 3rd gear will cause Code 69 to be displayed. Check for proper hydraulic operation before testing electrical components.
Code 69: Check Wiring. Check that vehicle harness connector is fully attached to transaxle bulkhead connector and that terminals are fully seated in connector. If connector or terminals are faulty, repair as required and repeat QUICK TEST. If connector and terminals are okay, go to next step.
Check Switch For Continuity. Install jumper harness to transaxle bulkhead connector. Using DVOM, check for continuity between engine ground and White wire. With engine running and transaxle in Drive, 1st gear, or 2nd gear, VOM should indicate no continuity (infinite resistance). When transaxle shifts into 3rd or 4th gear, the switch should close and resistance should be less than 10 ohms between White wire and engine ground. If circuit is okay, go to QUICK TEST and service codes as required. If circuit is not okay, go to next step.
Checking Internal Connections. Remove transaxle side oil pan. Check that internal connector with White wire is firmly attached to THS 3/2 pressure switch. Connector should not pull off easily or fit loosely. If connector is faulty, replace bulkhead connector and wiring assembly. Repeat QUICK TEST. If connector is okay, go to next step.
Check Internal Wiring. Remove connector from pressure switch by pushing on end of connector, while pulling on wire end of connector. Check for continuity in bulkhead connector by measuring resistance between White wire and terminal inside connector just removed. If reading is more than 2 ohms, replace bulkhead connector and wiring assembly. Repeat QUICK TEST. If reading is less than 2 ohms, go to next step.
Check THS 2/3 Switch. Remove THS 3/2 pressure switch. Install a 1/8-27 pipe fitting that can be connected to LOW pressure air supply in order to pressure leak and test switch closure. With 50 psi (3.5 kg/cm² ) applied, check for ruptured diaphragm by submerging switch in clean transmission fluid. NEVER use water to test switch. Check for bubbles coming out of small vent hole near switch terminal. If bubbles show, diaphragm has failed. Replace THS 3/2 pressure switch and repeat QUICK TEST. If no bubbles show, go to next step.
Check Switch Resistance. With 50 psi (3.5 kg/cm² ) applied to switch, check resistance between switch terminal and switch case. If reading is less than 8 ohms, hydraulic pressure circuit to switch may have excessive leaks. Service transaxle as required. If reading is more than 8 ohms, replace switch. Repeat steps 21) and 22), and then repeat QUICK TEST. Codes 39, 59, 62, 69 and 89 should no longer be displayed.
Code 89: LUS Circuit Failed. If Code 39 is also displayed, go to CIRCUIT TEST for that code. Check that vehicle harness connector is fully attached to transaxle bulkhead connector and that vehicle harness terminals are fully seated in connector. If connector or terminals are not okay, repair as required and repeat QUICK TEST. If connector and terminals are okay, go to next step.
Check Solenoid Resistance. Install jumper harness to transaxle bulkhead connector. Connect DVOM positive test lead to Red wire and negative test lead to Black wire. Check resistance. If reading is between 20 and 40 ohms, switch is okay, go to QUICK TEST and service codes as required. If reading is not between 20 and 40 ohms, go to next step.
Check Internal Connections. Remove transaxle side oil pan. Check that internal connector is fully attached to solenoid. If connector is okay, go to next step. If connector is not okay, fully engage connector and check continuity once more. If resistance is still not between 20 and 40 ohms, go to next step. If resistance is now okay, repeat QUICK TEST.
Check Solenoid Continuity. Remove connector from solenoid by pulling on wires at 2-way connector. Check solenoid continuity by connecting DVOM positive test lead to solenoid positive terminal and negative test lead to solenoid negative terminal (polarity symbols, + and -, are stamped on solenoid frame). If circuit is open (infinite resistance), replace solenoid and then repeat QUICK TEST. If solenoid is okay (20 to 40 ohms resistance), replace bulkhead connector and wiring assembly. Connect all internal connectors and repeat step 24). If circuit tests okay, install oil pan. Repeat KOEO SELF-TEST. Code 89 should no longer be displayed.
NOTE: The NPS is normally open and closes with hydraulic pressure. Failure of transaxle to engage in "D" or "R" will cause Code 57 to be displayed. Check for correct hydraulic pressure before testing electrical components.
Code 57: NPS Failed Open, Check Wiring. Check that vehicle harness connector is fully attached to transaxle connector and that vehicle harness terminals are fully seated in connector. If connector or terminals are not okay, repair as required and repeat QUICK TEST. If connector and terminals are okay, go to next step.
Check Switch For Continuity. Install jumper harness to transaxle bulkhead connector. Using DVOM, check continuity between Green wire and engine ground. With engine running and transaxle in "P" or "N", DVOM should indicate no continuity (infinite resistance). Shift transaxle into "R" and "D" ranges, switch should close. Resistance should be less than 10 ohms in both ranges. If circuit is okay, go to QUICK TEST and service codes as required. If circuit is not okay, go to next step.
Check Internal Connections. Remove transaxle side oil pan. Check that terminal connector with Green wire is firmly attached to NPS. Connector should not pull off easily or fit loosely. If connector is not okay, replace bulkhead connector and wiring assembly. Repeat QUICK TEST. If connector is okay, go to next step.
Check Internal Wiring. Remove connector from NPS by pushing on end of connector while pulling on connector wire. Check for continuity in bulkhead connector by measuring resistance between service connector Green wire and terminal inside connector just removed. If resistance is greater than 2 ohms, replace bulkhead connector and wiring assembly. Repeat QUICK TEST. If reading is less than 2 ohms, go to next step.
Check THS NPS Switch. Remove NPS. Install a 1/8-27 pipe fitting that can be connected to LOW pressure air supply in order to pressure leak and test switch closure. With 50 psi (3.5 kg/cm² ) applied, check for ruptured diaphragm by submerging switch in clean transmission fluid. NEVER use water to test switch. Check for bubbles coming out of small vent hole near switch terminal. If bubbles show, diaphragm has failed. Replace NPS and repeat QUICK TEST. If no bubbles show, go to next step.
Check Switch Resistance. With 50 psi (3.5 kg/cm² ) applied to switch, check resistance between switch terminal and switch case. If reading is 8 ohms or less, hydraulic pressure circuit to switch may have excessive leaks. Service transaxle as required. If reading is more than 8 ohms, replace switch. Repeat step 28), and then repeat QUICK TEST. Codes 39, 59, 62, 69 and 89 should no longer be displayed.
NOTE: The Transmission Temperature Switch (TTS) is a normally closed switch that opens when transmission oil temperature reaches 270°F (132°C). Perform the following test ONLY on a cool transmission. If the circuit has failed open, the ECA assumes the transmission is hot and applies the converter clutch more frequently to allow the transmission to cool.
Check Wiring. Check that vehicle harness connector is fully attached to transaxle connector and that vehicle harness terminals are fully seated in connector. If connector or terminals are not okay, repair as required and repeat QUICK TEST. If connector and terminals are okay, go to next step.
Check Bulkhead Connector. Ensure that the correct bulkhead connector has been installed. The connector should be "Natural" color and have 6 pin terminals. If connector is incorrect, replace connector. If connector is correct, go to next step.
Check Switch Circuit Continuity. Install jumper harness on transmission bulkhead connector. Using a DVOM, check continuity between engine ground and Yellow wire. Since the TTS is a normally closed switch, the circuit should be closed when the transmission temperature is less than 270°F (132°C). Resistance should be less than 10 ohms between the Yellow wire and ground. If circuit is okay, go to QUICK TEST procedures and service other codes. If circuit is faulty, go to next step.
Check Internal Connectors. Remove transaxle side oil pan. Check that terminal connector with Yellow wire is firmly attached to TTS. Connector should not pull off easily or fit loosely. If connector is faulty, replace bulkhead connector and wiring assembly. Repeat QUICK TEST. If connector is okay, go to next step.
Check Internal Wiring. Remove connector from TTS by pushing on end of connector while pulling on connector wire. Check for continuity in bulkhead connector by measuring resistance between service connector Green wire and terminal inside connector just removed. If resistance is greater than 2 ohms, replace bulkhead connector and wiring assembly. Repeat QUICK TEST. If reading is less than 2 ohms, go to next step.
Check Temperature Switch. Disconnect internal connector from switch. Check for continuity between engine ground and "Nail Head" connecting pin on the switch. Resistance should be less than 8 ohms. Ensure switch terminal is not loose or an intermittent open circuit may result. If resistance and switch test okay, testing is complete. If switch is faulty, replace switch, reconnect internal wiring and verify continuity to ground.
Neutral Pressure Switch (NPS) Failed Closed, Check Wiring. Remove vehicle harness connector from transaxle bulkhead connector and install jumper harness. Check continuity between engine ground and Green wire (NPS circuit). With engine off, resistance should be infinite. If resistance is infinite, switch has not failed in closed position. Service other codes as required. If there is continuity between the Green wire and ground, go to next step.
Check Internal Wiring. Remove oil pan and check for pinched, cut or otherwise grounded wiring. If wiring is faulty, replace transaxle bulkhead connector. Repeat QUICK TEST. If wiring is okay, go to next step.
Check NPS Switch. Remove wiring from NPS. Measure the pressure switch for continuity to engine ground. Connect one test lead to switch connector and other to engine ground. If resistance is infinite, switch is open, go to next step. If there is continuity to ground, replace NPS and repeat QUICK TEST.
Check Internal Wires. Remove wire from NPS and check continuity to ground. Connect one test lead to Green wire and other lead to ground. Ensure internal terminals are not shorted to ground. If there is continuity to ground, replace bulkhead connector and repeat QUICK TEST. If there is infinite resistance, repeat QUICK TEST and service codes as required.