PCC1302 Engine Power Loss of Speed Sense Shutdown Code 121 Solution

Here is a instruction show the step on how to diagnostics and repair PCC1302 engine power generation fault code 121 loss of speed sense shutdown trouble.

 

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Logic:
No engine speed signal detected from one of two signals: engine crankshaft speed or engine
camshaft position.

Possible Causes:
1.Faulty crankshaft speed sensor connections
2.Faulty crankshaft speed sensor
3.Faulty camshaft position sensor connections
4.Faulty camshaft position sensor
5.Faulty engine harness
6.Faulty extension harness
7.Damaged crankshaft target wheel
8.Verify the calibrations in the ECM and the PowerCommand controls

Diagnosis and Repair:
1.Faulty crankshaft speed sensor connections
a.Inspect the crankshaft speed sensor and the engine harness connector pins.
a.Disconnect the engine harness connector from the crankshaft speed sensor.
b.Inspect for corroded, bent broken, pushed back, expanded, or loose pins.
c.Inspect for evidence of moisture in or on the connector.

d.Inspect for missing or damaged connector seals.
e.Inspect for dirt or debris in or on the connector pins.

2.Faulty crankshaft speed sensor
a.Check the crankshaft speed sensor supply voltage.
a.Disconnect the engine harness connector from the crankshaft speed sensor.
b.Install the speed sensor breakout cable between the sensor and the sensor harness connector.
c.Measure the supply voltage by connecting the breakout cable’s supply and return connectors to the multimeter. If the reading is between 4.75 and 5.25 VDC, then the supply voltage is correct.
b.Check the crankshaft speed sensor signal (sense) voltage.
a.Disconnect the engine harness connector from the camshaft position sensor.
b.Install the pressure sensor breakout cable between the sensor and the sensor harness connector.
c.Measure the signal voltage by connecting the breakout cable’s signal and return connectors to the multimeter. If the reading is between 0.46 and 4.56 VDC, then the signal voltage is correct. If not, sensor is faulty.

3.Faulty camshaft position sensor connections
a.Inspect the camshaft position sensor and the engine harness connector pins
a.Disconnect the engine harness connector from the camshaft position sensor.
b.Inspect for corroded, bent broken, pushed back, expanded, or loose pins.
c.Inspect for evidence of moisture in or on the connector.
d.Inspect for missing or damaged connector seals.
e.Inspect for dirt or debris in or on the connector pins.

4.Faulty camshaft position sensor
a.Check the camshaft position sensor supply voltage.
a.Disconnect the engine harness connector from the camshaft position sensor.
b.Install the speed sensor breakout cable between the sensor and the sensor harness connector.
c.Measure the supply voltage by connecting the breakout cable’s supply and return connectors to the multimeter. If the reading is between 4.75 and 5.25 VDC, then the supply voltage is correct.
b.Check the camshaft position sensor signal (sense) voltage.
a.Disconnect the engine harness connector from the camshaft position sensor.
b.Install the pressure sensor breakout cable between the sensor and the sensor harness connector.
c.Measure the signal voltage by connecting the breakout cable’s signal and return connectors to the multimeter. If the reading is between 0.46 and 4.56 VDC, then the signal voltage is correct. If not, sensor is faulty.

 

5.Faulty engine harness
a.Inspect the engine harness and the connector pins.
a.Disconnect the engine harness connector from the extension harness.
b.Inspect for corroded pins, bent or broken pins, pushed back or expanded pins.
c.Inspect for evidence of moisture in or on the connector.
d.Inspect for missing or damaged connector seal.
e.Inspect for dirt or debris in or on the connector pin.

b.Check for a short circuit from pin to pin on the crankshaft speed sensor conductors.
a.Disconnect the engine harness from the extension harness.
b.Disconnect the engine harness connector from the crankshaft speed sensor.
c.Disconnect the engine harness from all sensors that have a shared supply or return with the crankshaft speed sensor.
d.Measure the resistance from the crankshaft speed 5 VDC supply pin on the engine harness inline connector to all other pins in the engine harness inline connector.
e.Measure the resistance from the crankshaft speed return pin on the engine harness inline connector to all other pins in the engine harness inline connector.
f.Measure the resistance from the crank shaft speed signal pin on the engine harness inline connector to all other pins in the engine harness inline connector.
g.If all measurements are greater than 100k ohms, then the resistance is correct.

c.Check for a short circuit to engine block ground on the crankshaft speed sensor conductors.
a.Disconnect the extension harness from the control.
b.Disconnect the extension harness from the engine harness.
c.Measure the resistance from the crankshaft speed signal pin on the extension harness connector to the engine block ground.
d.Measure the resistance from the crankshaft speed 5 VDC pin on the extension harness connector to the engine block ground.
e.If the measurement is more than 100k ohms, then the resistance is correct.

d.Check for an open circuit on the crankshaft speed sensor conductors.
a.Disconnect the engine harness connector from the extension harness.
b.Disconnect the engine harness from the crankshaft speed sensor.
c.Measure the resistance from the crankshaft speed return pin on the engine harness inline connector to the crankshaft speed return pin on the engine harness sensor connector.
d.If the measurement is less than 10 ohms, then the resistance is correct.

e.Check for a short circuit from pin to pin on the camshaft position sensor conductors.
a.Disconnect the engine harness from the extension harness.
b.Disconnect the engine harness connector from the camshaft position sensor.
c.Disconnect the engine harness from all sensors that have a shared supply or return with the camshaft position sensor.
d.Measure the resistance from the camshaft position 5 VDC supply pin on the engine harness inline connector to all other pins in the engine harness inline connector.
e.Measure the resistance from the camshaft position return pin on the engine harness inline connector to all other pins in the engine harness inline connector.
f.Measure the resistance from the camshaft position signal pin on the engine harness inline connector to all other pins in the engine harness inline connector.
g.If all measurements are greater than 100k ohms, then the resistance is correct.

f.Check for a short circuit to engine block ground on the camshaft position sensor conductors.
a.Disconnect the extension harness from the control.
b.Disconnect the extension harness from the engine harness.
c.Measure the resistance from the camshaft position signal pin on the extension harness connector to the engine block ground.
d.Measure the resistance from the camshaft position 5 VDC pin on the extension harness connector to the engine block ground.
e.If the measurement is more than 100k ohms, then the resistance is correct.

g.Check for an open circuit on the camshaft position sensor conductors.
a.Disconnect the engine harness connector from the extension harness.
b.Disconnect the engine harness from the camshaft position sensor.
c.Measure the resistance from the camshaft position return pin on the engine harness inline connector to the camshaft position return pin on the engine harness sensor connector.
d.If the measurement is less than 10 ohms, then the resistance is correct.

6.Faulty extension harness
a.Inspect the extension harness and control pins.
a.Disconnect the extension harness connector from the control.
b.Inspect for corroded, bent broken, pushed back, expanded, or loose pins.
c.Inspect for evidence of moisture in or on the connector.
d.Inspect for missing or damaged connector seals.
e.Inspect for dirt or debris in or on the connector pins.

b.Check for a short circuit from pin to pin on the crankshaft speed sensor conductors.
a.Disconnect the extension harness connector from the control.
b.Disconnect the extension harness from the engine harness.
c.Measure the resistance from the crankshaft speed sensor 5 VDC supply pin on the extension harness connector to all other pins in the extension harness connector.
d.Measure the resistance from the crankshaft speed return pin on the extension harness connector to all other pins in the extension harness connector.
e.Measure the resistance from the crankshaft speed signal pin on the extension harness connector to all other pins in the extension harness connector.
f.If all measurements are greater than 100k ohms, then the resistance is correct.

c.Check for a short circuit to engine block ground on the crankshaft speed sensor conductors.
a.Disconnect the extension harness from the control.
b.Disconnect the extension harness from the engine harness.
c.Measure the resistance from the crankshaft speed signal pin on the extension harness connector to the engine block ground.
d.Measure the resistance from the crankshaft speed 5 VDC pin on the extension harness connector to the engine block ground.
e.If the measurement is more than 100k ohms, then the resistance is correct.

d.Check for an open circuit on the crankshaft speed sensor conductors.
a.Disconnect the extension harness from the control.
b.Disconnect the extension harness from the engine harness.
c.Measure the resistance from the crankshaft speed return pin on the engine harness inline connector to the crankshaft speed return pin on the engine harness sensor connector.
d.If the measurement is less than 10 ohms, then the resistance is correct.

e.Check for a short circuit from pin to pin on the camshaft position sensor conductors.
a.Disconnect the extension harness connector from the control.
b.Disconnect the extension harness from the engine harness.
c.Measure the resistance from the camshaft position sensor 5 VDC supply pin on the extension harness connector to all other pins in the extension harness connector.
d.Measure the resistance from the camshaft position return pin on the extension harness connector to all other pins in the extension harness connector.
e.Measure the resistance from the camshaft position signal pin on the extension harness connector to all other pins in the extension harness connector.
f.If all measurements are greater than 100k ohms, then the resistance is correct.

f.Check for a short circuit to engine block ground on the camshaft position sensor conductors.
a.Disconnect the extension harness from the control.
b.Disconnect the extension harness from the engine harness.
c.Measure the resistance from the camshaft position signal pin on the extension harness connector to the engine block ground.
d.Measure the resistance from the camshaft position 5 VDC pin on the extension harness connector to the engine block ground.
e.If the measurement is more than 100k ohms, then the resistance is correct.

g.Check for an open circuit on the camshaft position sensor conductors.
a.Disconnect the extension harness from the control.
b.Disconnect the extension harness from the engine harness.
c.Measure the resistance from the camshaft position return pin on the engine harness inline connector to the camshaft position return pin on the engine harness sensor connector.
d.If the measurement is less than 10 ohms, then the resistance is correct.

7.Damaged crankshaft target wheel
a.Visually inspect the crankshaft target wheel.
a.Inspect for damaged, malformed, missing or broken target wheel teeth.
b.Inspect for evidence of corrosion or other materials on or around the target wheel teeth.
c.Inspect for dirt or debris on the target wheel teeth.

8.Verify the calibrations in the ECM and the PowerCommand controls.
a.Using the display or the InPower Service tool, verify the calibration in the PCC.
a.If the calibration in the PCC matches the latest calibration on the InCal website, then the calibration is correct. If it does not, update the calibration to the latest.
b.Using the InSite Service tool, verify the calibration in the ECM.
a.If the calibration in the ECM matches the latest calibration on QSOL, then the calibration is correct. If it does not, update the ECM to the latest calibration.

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