Caterpillar — Test Step 18. Check the Voltage at the ECM
Testing & diagnosis · Engine ECM connector P1
From a Caterpillar service manual covering: 3500B Engine, PM3516, PM3516 Power Module. Check it applies to your exact model before use.
Applies to: Caterpillar 3500B engine
Before you start
- The status screen on the ET displays INVALID DATA when the ECM reads a signal that is out of range.
Procedure
- Turn the ECS to the OFF/RESET position, then ON with engine OFF.
- Measure analog voltage between suspect sensor signal voltage and sensor return at ECM P1.
- Observe the sensor reading on the ET status screen.
- Turn ECS OFF/RESET, then ON with engine OFF.
- Measure frequency and duty cycle between digital sensor signal and return at ECM P1.
- Start the engine and observe the ET status screen.
Tools required
- ET (Electronic Technician) Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Analog signal voltage 0.2 to 0.6 VDC
- Frequency 150 Hz to 1000 Hz
- Duty cycle 10-21% below 49 °C, 22-88% between 49 °C and 851 °C, 80-90 FridayParts $32.86% above 851 °C
- ET should read 30 °C (86 °F) while engine is cold
Source: Caterpillar service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.