DTC 21
DTC 21: Crankshaft Position Sensor System
CIRCUIT OPERATION
The crankshaft position sensor power is supplied from the MFI relay (terminal 3), and the ground (terminal 1) is provided on the PCM. The PCM supplies a five-volts voltage to crankshaft position sensor output terminal (terminal 2). The crankshaft position sensor generates a pulse signal when the output terminal is opened and grounded. The sensor is opened and closed as the flat on the crankshaft passes by.
DTC SET CONDITIONS
If no output pulse is detected from the crankshaft position sensor for five seconds or more while driving at 25 km/h (16 mph) or more, it is judged that there is an open circuit in the crankshaft position sensor and diagnostic trouble code number "21" is output.
TROUBLESHOOTING HINTS (The most likely causes for this code to be set:)
^ Malfunction of the crankshaft position 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 21: Crankshaft Position 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 link connector.
2. With the gear selector lever in the "P" position, start the engine and run at idle.
3. Set scan tool MB991502 to data reading mode for item 21: Crankshaft Position Sensor.
^ When the accelerator pedal is not depressed (throttle valve is fully closed) the display should be "600 to 900 r/ min."
^ With the accelerator pedal depressed, the engine speed display should increase according to engine speed.
Q: Is the sensor operating properly?
YES: This malfunction is intermittent.
NO: Go to Step 2.
STEP 2. Using the oscilloscope, check the waveform at crankshaft position sensor connector B-117.
1. Do not disconnect connector B-117.
2. Connect an oscilloscope probe to crankshaft position sensor connector B-117 terminal 2 by backprobing.
3. With the gear selector lever in the "P" position, start the engine and run at idle.
4. Check the waveform.
^ The waveform should show a pattern similar to the illustration. The maximum value should be 4.8 volts and more and the minimum value 0.6 volts and less.
5. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the waveform normal?
YES: Go to Step 3.
NO: Go to Step 5.
STEP 3. Check connectors B-117 at crankshaft position sensor and C-118 at PCM for damage.
Q: Are the connectors in good condition?
YES: Go to Step 4.
NO: Repair or replace the defective connectors.
STEP 4. Using scan tool MB991502, check data list item 21: Crankshaft Position 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 link connector.
2. With the gear selector lever in the "P" position, start the engine and run at idle.
3. Set scan tool MB991502 to data reading mode for item 21: Crankshaft Position Sensor.
^ When the accelerator pedal is not depressed (throttle valve is fully closed) the display should be "600 to 900 r/min."
^ With the accelerator pedal depressed, the engine speed should increase according to engine speed.
Q: Is the sensor operating properly?
YES: This malfunction is intermittent.
NO: Replace the PCM.
STEP 5. Check connector B-117 at crankshaft position sensor for damage.
Q: Is the connector in good condition?
YES: Go to Step 6.
NO: Repair or replace it.
STEP 6. Check the sensor output voltage at crankshaft position sensor connector B-117.
1. Disconnect connector B-117 and measure at the harness side.
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between terminal 2 and ground.
^ Voltage should be between 4.9 and 5.1 volts.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the voltage normal?
YES: Go to Step 11.
NO: Go to Step 7.
STEP 7. Check the sensor output voltage at PCM connector C-118 by backprobing.
1. Do not disconnect connector C-118.
2. Disconnect connector B-117 at crankshaft position sensor.
3. Turn the ignition switch to the "ON" position.
4. Measure the voltage between terminal 45 and ground by backprobing.
^ Voltage should be between 4.9 and 5.1 volts.
5. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the voltage normal?
YES: Go to Step 8.
NO: Go to Step 9.
STEP 8. Check connector C-118 at PCM for damage.
Q: Is the connector in good condition?
YES: Repair harness open circuit between crankshaft position sensor connector B-117 terminal 2 and PCM connector C-118 terminal 45.
NO: Repair or replace it.
STEP 9. Check connector C-118 at PCM for damage.
Q: Is the connector in good condition?
YES: Go to Step 10.
NO: Repair or replace it.
STEP 10. Check harness for short circuit to ground between crankshaft position sensor connector B-117 terminal 2 and PCM connector C-118 terminal 45.
Q: Is the harness wire in good condition?
YES: Go to Step 4.
NO: Repair it.
STEP 11. Check the power supply voltage at crankshaft position sensor connector B-117.
1. Disconnect connector B-117 and measure at the harness side.
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between terminal 3 and ground.
^ Voltage should be battery positive voltage.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the voltage normal?
YES: Go to Step 13.
NO: Go to Step 12.
STEP 12. Check connector B-12X at MFI relay for damage.
Q: Is the connector in good condition?
YES: Repair harness open circuit or short circuit to ground between MFI relay connector B-12X terminal 4 and crankshaft position sensor connector B-117 terminal 3.
NO: Repair or replace it.
STEP 13. Check the continuity at crankshaft position sensor connector B-117.
1. Disconnect connector B-117 and measure at the harness side.
2. Check for the continuity between terminal 1 and ground.
^ Should be less than 2 ohm.
Q: Is the continuity normal?
YES: Go to Step 18.
NO: Go to Step 14.
STEP 14. Check the ground voltage at PCM connector C120 by backprobing.
1. Do not disconnect connector C-120.
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between terminal 16 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 15.
NO: Go to Step 16.
STEP 15. Check connector C-120 at PCM for damage.
Q: Is the connector in good condition?
YES: Repair harness open circuit or damage between crankshaft position sensor connector B-117 terminal 1 and PCM connector C-120 terminal 16.
NO: Repair or replace it.
STEP 16. Check connector C-120 at PCM for damage.
Q: Is the connector in good condition?
YES: Go to Step 17.
NO: Repair or replace it.
STEP 17. Check the harness for short circuit to ground between crankshaft position sensor connector B-117 terminal 1 and PCM connector C-120 terminal 16.
Q: Is the harness wire in good condition?
YES: Go to Step 4.
NO: Repair it.
STEP 18. Check connectors C-118 and C-120 at PCM and B-12X at the MFI relay for damage.
Q: Are the harness connectors in good condition?
YES: Go to Step 19.
NO: Repair or replace the defective connectors.
STEP 19. Check the harness for damage between crankshaft position sensor connector B-117 terminal 1 and PCM connector C-120 terminal 16.
Q: Is the harness wire in good condition?
YES: Go to Step 20.
NO: Repair it.
STEP 20. Check the harness for damage between crankshaft position sensor connector B-117 terminal 2 and PCM connector C-118 terminal 45.
Q: Is the harness wire in good condition?
YES: Go to Step 21.
NO: Repair it.
STEP 21. Check the harness for damage between MFI relay connector B-12X terminal 4 and crankshaft position sensor connector B-117 terminal 3.
Q: Is the harness wire in good conditions
YES: Go to Step 22.
NO: Repair it.
STEP 22. Check the crankshaft position sensor vane.
Q: Is the vane in good condition?
YES: Replace the crankshaft position sensor.
NO: Repair or replace it.