MBE 900/4000 SID 21 – Crankshaft Position Sensor Outside of Normal Operating Conditions

Description of SID 21 – Crankshaft Position Sensor Outside of Normal Operating Conditions

SID 021 indicates that the PLD-MR control unit has detected the Crankshaft Position (CKP) sensor operating outside of normal operating conditions.‪

The diagnostic condition is typically:‪

  • CKP Sensor Signal Voltage Too Low (021 01)
  • CKP Sensor Open Circuit (021 03)
  • CKP Sensor Short to Ground (021 04)
  • No Match of Camshaft and Crankshaft Signals (021 07)
  • CKP Sensor Time Out (021 08)
  • CKP Sensor Pins Swapped (021 14)

See Figure “Sensor Location on MBE 6-Cylinder Engine” for sensor locations on the typical MBE 6-cylinder engine. ‪

Note: Sensor locations are similar on the 4-cylinder engine. The Engine Oil Level (EOL) sensor, if used, is located at the bottom of the oil pan.

Note: * The Baro sensor is integrated into the PLD-MR unit.

 1. Engine Oil Pressure (EOP) Sensor‪  5. Barometric Pressure (Baro) Sensor *‪
 2. Engine Coolant Temperature (ECT) Sensor‪  6. Camshaft Position (CMP) Sensor – on Cylinder Block ‪
 3. Intake Manifold Pressure (IMP) Sensor‪  7. CKP Sensor – on Timing Case‪
 4. Supply Fuel Temperature (SFT) Sensor‪  ‪

Figure 1. Sensor Location on MBE 6-Cylinder Engine

The engine harness is delivered to the factory with the engine sensors and the PLD-MR already connected. See Figure “Typical On-Highway Six-Cylinder Engine Harness” for a typical six-cylinder engine harness. Engine harness sensor pin locations are listed in Table “Selected Harness Pin Locations” .‪

Figure 2. Typical On-Highway Six-Cylinder Engine Harness

Pin ‪ Wire Color ‪ Signal Type ‪ Function ‪ Connector ‪
6- Cylinder ‪ 4- Cylinder ‪
1‪ Blk/Yel‪ Blk/Yel‪ Sensor Return‪ CMP Sensor (-)‪

Front Looking into the Pins‪

2‪ Blk/Viol‪ Blk/Viol‪ Sensor Return‪ CKP Sensor (-)‪
19‪ Brn/Viol‪ Brn/Viol‪ Frequency Input‪ CKP Sensor (+)‪
20‪ Brn/Yel‪ Brn/Yel‪ Frequency Input‪ CMP Sensor (+)‪
Table 2. Selected Harness Pin Locations

The CKP sensor and its bracket are located on the flywheel housing. See Figure “Crankshaft Position Sensor and Bracket Location” . In most cases the CKP sensor bracket is replaced only when the flywheel housing is replaced.‪

 1. CKP Sensor Bracket‪  4. CKP Sensor‪
 2. Shear Bolt (2 Qty.)‪  5. Reference Hole on Flywheel Edge‪
 3. Spring Bushing‪  ‪

Figure 3. Crankshaft Position Sensor and Bracket Location

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