MBE 900 4000 Troubleshooting – Section 19.1 Description of SID 21 – Crankshaft Position Sensor Outside of Normal Operating Conditions

Section 19.1
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 (+)‪

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