Circuit Description
The engine speed sensor provides engine speed information to the electronic control module (ECM). The sensor must be powered up by +5 VDC to operate.
The sensor generates its signals by sensing the movement of target teeth cast into a tone wheel that is mounted to the crankshaft. The tone wheel has 35 teeth and a gap where the 36th tooth would be placed. This missing tooth indicates that cylinder No. 1 (and No. 6) is at top dead center.
Component Location
The engine speed sensor is located on the intake side of the engine block, at crankshaft level, between cylinders No. 4 and No. 5.
Cummins ISB CM550 (1990-94) Fault Code: 222 PID: 108 SPN: 108 FMI: 4 Ambient Air Pressure Sensor Circuit
Cummins ISB CM550 (1990-94) Fault Code: 221 PID: 108 SPN: 108 FMI: 3 Ambient Air Pressue Sensor Circuit
Cummins ISB CM550 (1990-94) Fault Code: 191 PID: 50 SPN: 876 FMI: 11 Air Conditioner Clutch Supply Circuit
Cummins ISB CM550 (1990-94) Fault Code: 155 PID: 105 SPN: 105 FMI: 0 Intake Manifold Air Temperature Sensor – Engine Protection Circuit
Cummins ISB CM550 (1990-94) Fault Code: 154 PID: 105 SPN: 105 FMI: 4 Intake Manifold Air Temperature Sensor Circuit
Cummins ISB CM550 (1990-94) Fault Code: 154 PID: 105 SPN: 105 FMI: 3 Intake Manifold Air Temperature Sensor Circuit
