DTC 15
DTC 15: A/T Fluid Temperature Sensor System (Open Circuit)
CIRCUIT OPERATION
^ The PCM (terminal 124) applies 5 volts to the A/T fluid temperature sensor output terminal (terminal 1).
^ Ground terminal (terminal 2) is grounded to the PCM (terminal 57).
^ The A/T fluid temperature sensor is an NTC (negative temperature coefficient) type of resistor. When the A/T fluid temperature rises, the resistance decreases.
^ The A/T fluid temperature sensor output voltage rises when the resistance increases (cools), and drops when the resistance decreases (heats up).
DTC SET CONDITIONS
If the A/T fluid temperature sensor output voltage is 4.5 volts or more after driving for 10 minutes or more (if the A/T fluid temperature does not increase), there is an open circuit in the A/T fluid temperature sensor and diagnostic trouble code number "15" is set.
TROUBLESHOOTING HINTS (The most likely causes for this code to be set:)
^ Malfunction of the A/T fluid temperature sensor circuit
^ Damaged harness, connector
^ Malfunction of the PCM
DIAGNOSIS
Required Special Tool: MB991502: Scan Tool (MUT-II)
STEP 1. Using scan tool MB991502, check data list item 15: A/T Fluid Temperature Sensor.
CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.
1. Connect scan tool MB991502 to the data fink connector.
2. Start the engine.
3. Set scan tool MB991502 to data reading mode for item 15: A/T Fluid Temperature Sensor.
^ At cool condition: Almost equal to the ambient temperature (atmospheric temperature)
^ At warm condition: 70 to 80°C (158 to 176°F)
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?
YES: This malfunction is intermittent.
NO: Go to Step 2.
STEP 2. Check the ground voltage at PCM connector C-118 by backprobing.
1. Do not disconnect connector C-118.
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between terminal 57 and ground by backprobing.
^ Voltage should be 0.5 volt or less.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the voltage normal?
YES: Go to Step 5.
NO: Go to Step 3.
STEP 3. Check connector C-118 at PCM for damage.
Q: Is the connector in good condition?
YES: Go to Step 4.
NO: Repair or replace it.
STEP 4. Using scan tool MB991502, check data list item 15: A/T Fluid Temperature Sensor.
CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.
1. Connect scan tool MB991502 to data link connector.
2. Start the engine.
3. Set scan tool MB991502 to the data reading mode for item 15: A/T Fluid Temperature Sensor.
^ At cool condition: Almost equal to the ambient temperature (atmospheric temperature)
^ At warm condition: 70 to 80°C (158 to 176°F)
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?
YES: This malfunction is intermittent.
NO: Replace the PCM.
STEP 5. Check the sensor output voltage at PCM connector C-114 by backprobing.
1. Do not disconnect connector C-114.
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between terminal 124 and ground by backprobing.
^ When A/T fluid temperature is 20°C (68°F), voltage should be between 3.8 and 4.0 volts.
^ When A/T fluid temperature is 40°C (104°F), voltage should be between 3.2 and 3.4 volts.
^ When A/T fluid temperature is 80°C (176°F), voltage should be between 1.7 and 1.9 volts.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the voltage normal?
YES: Go to Step 6.
NO: Go to Step 7.
STEP 6. Check connector C-114 at PCM for damage.
Q: Is the connector in good condition?
YES: Go to Step 4.
NO: Repair or replace it.
STEP 7. Check connectors C-118 and C-114 at PCM and B15 at A/T control solenoid valve assembly for damage.
Q: Are the harness connectors in good condition?
YES: Go to Step 8.
NO: Repair or replace the defective connectors.
STEP 8. Check the A/T fluid temperature sensor at A/T control solenoid valve assembly connector B-15.
1. Disconnect connector B-15 and measure at the sensor side.
2. Measure the resistance between terminal 1 and 2.
^ When A/T fluid temperature is 0°C (32°F), resistance should be between 16.7 and 20.5 kilo ohm.
^ When A/T fluid temperature is 20°C (68°F), resistance should be between 7.3 and 8.9 kilo ohm.
^ When A/T fluid temperature is 40°C (104°F), resistance should be between 3.4 and 4.2 kilo ohm.
^ When A/T fluid temperature is 80°C (176°F), resistance should be between 1.9 and 2.2 kilo ohm.
^ When A/T fluid temperature is 100°C (212°F), resistance should be between 0.57 and 0.69 kilo ohm.
Q: Is the resistance normal?
YES: Go to Step 9.
NO: Replace the A/T fluid temperature sensor.
STEP 9. Check the power supply voltage at A/T control solenoid valve assembly connector B-15.
1. Disconnect connector B-15 and measure at the harness side.
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between terminal 1 and ground.
^ Voltage should be between 4.5 and 4.9 volts.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the voltage normal?
YES: Go to Step 10.
NO: Repair harness open circuit between A/T control solenoid valve assembly connector B-15 terminal 1 and PCM connector C-114 terminal 124.
STEP 10. Check the continuity at A/T control solenoid valve assembly connector B-15.
1. Disconnect connector B-15 and measure at the harness side.
2. Check for the continuity between terminal 2 and ground.
^ Should be less than 2 ohm.
Q: Is the continuity normal?
YES: Go to Step 11.
NO: Repair harness open circuit or damage between A/T control solenoid valve assembly connector B-15 terminal 2 and PCM connector C-118 terminal 57.
STEP 11. Check harness for damage between A/T control solenoid valve assembly connector B-15 terminal 1 and PCM connector C-114 terminal 124.
Q: Is the harness wire in good condition?
YES: Repair harness damage between A/T control solenoid valve assembly connector B-15 terminal 2 and PCM connector C-118 terminal 57.
NO: Repair it.