DTC 21

DTC 21: Crankshaft Position Sensor System

Part 1 Of 2:

Part 2 Of 2:

CIRCUIT OPERATION
The crankshaft position sensor power is supplied from the MFI relay (terminal 4) to the crankshaft position sensor (terminal 3). The crankshaft position sensor (terminal 1) is grounded by the PCM (terminal 16). The PCM (terminal 45) supplies 5 volts to the crankshaft position sensor output (terminal 2). The crankshaft position sensor detects the crank angle (position) of each cylinder, and converts that data to pulse signals that are sent to the PCM.

DTC SET CONDITIONS
If the crankshaft position sensor does not detect an output pulse for more than 5 seconds while driving more than 25 km/h (16 mph), it is judged that there is an open circuit in the crankshaft position sensor and DTC 21 is set.

TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
^ Malfunction of the crankshaft position sensor circuit
^ Damaged harness or connector
^ Malfunction of the PCM

DIAGNOSIS

Required Special Tool:
^ MB991958: Scan Tool (MUT-III Sub Assembly)
^ MB991824: V.C.I.
^ MB991827: MUT-III USB Cable
^ MB991911: MUT-III Main Harness B

STEP 1. Using scan tool MB991958, check data list item 21: Crankshaft Position Sensor.

CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.





1) Connect scan tool MB991958 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 MB991958 to data reading mode for item 21: Crankshaft Position Sensor.
^ When the accelerator pedal is not depressed (throttle valve is fully closed) the display on the scan tool MB991958 should be "600 to 900 r/min."
^ With the accelerator pedal depressed, the engine speed display on the scan tool MB991958 should increase according to engine speed.
Q: Does the engine speed display increase according to engine speed when the accelerator pedal is depressed?
YES: It can be assumed that this malfunction is intermittent.
NO: Go to Step2.

STEP 2. Using the oscilloscope, check the waveform at crankshaft position sensor connector B-20.








1) Do not disconnect connector B-20.





2) Connect an oscilloscope probe between crankshaft position sensor connector B-20 terminal 2 and ground 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 or more and the minimum value 0.6 volt or less. The output waveform should not contain electrical noise.
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 crankshaft position sensor connector B-20 and PCM connector C-54 <2.4L Engine> or C-55 <3.0L Engine> for loose, corroded or damaged terminals, or terminals pushed back in the connector.











Q: Are the connectors and terminals in good condition?
YES: Go to Step 4.
NO: Repair or replace the damaged components.

STEP 4. Using scan tool MB991958, check data list item 21: Crankshaft Position Sensor.

CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.





1) Connect scan tool MB991958 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 MB991958 to data reading mode for item 21: Crankshaft Position Sensor.
^ When the accelerator pedal is not depressed (throttle valve is fully closed) the display on the scan tool MB991958 should be "600 to 900 r/min."
^ With the accelerator pedal depressed, the engine speed display on the scan tool MB991958 should increase according to engine speed.
Q: Does the engine speed display increase according to engine speed when the accelerator pedal is depressed?
YES: It can be assumed that this malfunction is intermittent.
NO: Replace the PCM.

STEP 5. Check crankshaft position sensor connector B-20 for loose, corroded or damaged terminals, or terminals pushed back in the connector.








Q: Are the connector and terminals in good condition?
YES: Go to Step 6.
NO: Repair or replace the damaged components.

STEP 6. Measure the sensor output voltage at crankshaft position sensor connector B-20.








1) Disconnect connector B-20 and measure at the harness side.
2) Turn the ignition switch to the "ON" position.





3) Measure the voltage between terminal 2 and ground.
^ The voltage should measure between 4.9 and 5.1 volts.
4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage between 4.9 and 5.1 volts?
YES: Go to Step 12.
NO: Go to Step 7.

STEP 7. Measure the sensor output voltage at PCM connector C-54 <2.4L Engine> or C-55 <3.0L Engine> by backprobing.





1) Do not disconnect connector C-54 <2.4L Engine> or C-55 <3.0L Engine>.
2) Disconnect connector B-20 at the 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 measure between 4.9 and 5.1 volts.
5) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage between 4.9 and 5.1 volts?
YES: Go to Step 8.
NO: Go to Step 10.

STEP 8. Check PCM connector C-54 <2.4L Engine> or C-55 <3.0L Engine> for loose, corroded or damaged terminals, or terminals pushed back in the connector.





Q: Are the connector and terminals in good condition?
YES: Go to Step 9.
NO: Repair or replace the damaged components.

STEP 9. Check the harness for open circuit between crankshaft position sensor connector B-20 terminal 2 and PCM connector C-54 <2.4L Engine> or C-55 <3.0L Engine> terminal 45.

Q: Is the harness wire in good condition?
YES: Go to Step 4.
NO: Repair or replace the harness wire.

STEP 10. Check PCM connector C-54 <2.4L Engine> or C-55 <3.0L Engine> for loose, corroded or damaged terminals, or terminals pushed back in the connector.





Q: Are the connector and terminals in good condition?
YES: Go to Step 11.
NO: Repair or replace the damaged components.

STEP 11. Check the harness for a short circuit to ground between crankshaft position sensor connector B-20 terminal 2 and PCM connector C-54 <2.4L Engine> or C-55 <3.0L Engine> terminal 45.

Q: Is the harness wire in good condition?
YES: Go to Step 4.
NO: Repair or replace the harness wire.

STEP 12. Measure the power supply voltage at crankshaft position sensor connector B-20.








1) Disconnect connector B-20 and measure at the harness side.
2) Turn the ignition switch to the "ON" position.





3) Measure the voltage between terminal 3 and ground.
^ The voltage should measure battery positive voltage.
4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage battery positive voltage?
YES: Go to Step 15.
NO: Go to Step 13.

STEP 13. Check MFI relay connector A-18X in the engine component relay box for loose, corroded or damaged terminals, or terminals pushed back in the connector.





Q: Are the connector and terminals in good condition?
YES: Go to Step 14.
NO: Repair or replace the damaged components.

STEP 14. Check the harness for open circuit or short circuit to ground between MFI relay connector A-18X terminal 4 in the engine component relay box and crankshaft position sensor connector B-20 terminal 3.











Q: Is the harness wire in good condition?
YES: Go to Step 4.
NO: Repair or replace the harness wire.

STEP 15. Measure the resistance of the ground circuit at crankshaft position sensor connector B-20.








1) Disconnect connector B-20 and measure at the harness side.





2) Measure the resistance between terminal 1 and ground.
^ The resistance should measure less than 2 ohms.
Q: Is the resistance less than 2 ohms?
YES: Go to Step 21.
NO: Go to Step 16.

STEP 16. Measure the ground voltage at PCM connector C-50 <2.4L Engine> or C-52 <3.0L Engine> by backprobing.





1) Do not disconnect connector C-50 <2.4L Engine> or C-52 <3.0L Engine>.
2) Turn the ignition switch to the "ON" position.





3) Measure the voltage between terminal 16 and ground by backprobing.
^ The voltage should measure 0.5 volt or less.
4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage 0.5 volt or less?
YES: Go to Step 17.
NO: Go to Step 19.

STEP 17. Check PCM connector C-50 <2.4L Engine> or C-52 <3.0L Engine> for loose, corroded or damaged terminals, or terminals pushed back in the connector.





Q: Are the connector and terminals in good condition?
YES: Go to Step 18.
NO: Repair or replace the damaged components.

STEP 18. Check the harness for open circuit or damage between crankshaft position sensor connector B-20 terminal 1 and PCM connector C-50 <2.4L Engine> or C-52 <3.0L Engine> terminal 16.

Q: Is the harness wire in good condition?
YES: Go to Step 4.
NO: Repair or replace the harness wire.

STEP 19. Check PCM connector C-50 <2.4L Engine> or C-52 <3.0L Engine> for loose, corroded or damaged terminals, or terminals pushed back in the connector.





Q: Are the connector and terminals in good condition?
YES: Go to Step 20.
NO: Repair or replace the damaged components.

STEP 20. Check the harness for a short circuit to ground between crankshaft position sensor connector B-20 terminal 1 and PCM connector C-50 <2.4L Engine> or C-52 <3.0L Engine> terminal 16.











Q: Is the harness wire in good condition?
YES: Go to Step 4.
NO: Repair or replace the harness wire.

STEP 21. Check PCM connectors C-50 <2.4L Engine> or C-52 <3.0L Engine> and C-54 <2.4L Engine> or C-55 <3.0L Engine>, and MFI relay connector A-18X for loose, corroded or damaged terminals, or terminals pushed back in the connector.








Q: Are the connectors and terminals in good condition?
YES: Go to Step 22.
NO: Repair or replace the damaged components.

STEP 22. Check the harness for damage between crankshaft position sensor connector B-20 terminal 1 and PCM connector C-50 <2.4L Engine> or C-52 <3.0L Engine> terminal 16.











Q: Is the harness wire in good condition?
YES: Go to Step 23.
NO: Repair or replace the harness wire.

STEP 23. Check the harness for damage between crankshaft position sensor connector B-20 terminal 2 and PCM connector C-54 <2.4L Engine> or C-55 <3.0L Engine> terminal 45.











Q: Is the harness wire in good condition?
YES: Go to Step 24.
NO: Repair or replace the harness wire.

STEP 24. Check the harness for damage between MFI relay connector A-18X terminal 4 in the engine component relay box and crankshaft position sensor connector B-20 terminal 3.











Q: Is the harness wire in good condition?
YES: Go to Step 25.
NO: Repair or replace the harness wire.

STEP 25. Check the crankshaft angle sensing blade.
Q: Is the crankshaft angle sensing blade in good condition?
YES: Replace the crankshaft position sensor.
NO: Replace the crankshaft angle sensing blade.