Crankshaft Position Sensor Signal Lost or Erratic

Common Symptoms

• Tractor cranks normally but will not fire and start
• Engine starts briefly then stalls within a few seconds of running
• DTC P0335 appears on the instrument cluster fault display on Tier 4 Final models
• RPM gauge reads zero or jumps erratically while cranking
• Check engine or engine warning light illuminates on the dash
• Engine stalls suddenly at idle or under load with no other warning
• Tractor has hard starts or extended cranking before catching, especially when warm

Probable Causes (Ranked by Likelihood)

• Crankshaft position sensor has failed internally, open or short circuit in the sensor body Very Likely
• Wiring harness to the crankshaft position sensor is chafed, corroded, or has a broken wire at the connector Very Likely
• Sensor connector is contaminated with oil, dirt, or moisture causing a poor signal Likely
• Reluctor ring (tone wheel) on the crankshaft is damaged, missing a tooth, or packed with debris Possible
• Air gap between the sensor tip and reluctor ring is out of specification due to sensor mounting or ring movement Possible
• ECM power or ground supply is weak, causing the ECM to misread or drop the crank signal Less Likely
• ECM internal fault causing failure to process the crank position signal correctly Less Likely

Step-by-Step Diagnostic Procedure

1. Step 1. Before anything else, check the battery voltage with a multimeter. A weak battery that drops below 10.5 volts during cranking can mimic a crank sensor fault. Charge or load-test the battery if voltage is low.

2. Step 2. Locate the crankshaft position sensor. On most Mahindra common-rail engines it mounts on the lower block near the flywheel housing or front timing cover. Refer to your model's service manual for exact location.

3. Step 3. Unplug the sensor connector and inspect it closely. Look for bent pins, green corrosion, oil intrusion, or pushed-back terminals. Clean the connector with electrical contact cleaner and let it dry completely before reconnecting.

4. Step 4. With the connector still unplugged and the key OFF, set your multimeter to resistance (ohms). Measure resistance across the two signal pins on the sensor itself. A healthy sensor typically reads between 900 and 1,200 ohms on Mahindra common-rail variants. A reading of zero (short) or infinite (open) means the sensor has failed and must be replaced.

5. Step 5. Check the wiring between the sensor and ECM. With the key OFF, use the multimeter in continuity mode to verify each wire in the sensor harness has continuity end to end. Also check for a short to ground by measuring resistance from each signal wire to the tractor frame. You should see no continuity to ground on signal wires.

6. Step 6. Inspect the reluctor ring (the toothed ring the sensor reads) through the sensor mounting hole or with the sensor removed. Look for packed mud, metallic debris, or a chipped or missing tooth. Clean any debris and look again. A damaged ring requires internal engine access, which is advanced work.

7. Step 7. Check the sensor air gap if the sensor mounts with a set bolt. Typical air gap spec on Mahindra engines is 0.5 to 1.5 mm. Use a feeler gauge. An out-of-spec gap means the sensor is not reading the ring cleanly. Loosen the mount and adjust or use the correct shim.

8. Step 8. If the sensor and wiring test good and the fault persists, the diagnosis moves beyond basic tools. At this point you need the Mahindra dealer scan tool to check live crank signal data and ECM supply voltages, and to rule out an ECM fault. Contact your Mahindra dealer.

Frequently Asked Questions