2000/07/01 Caterpillar

Truck Engines:

3406E (S/N: 1MM1-UP; 2WS1-UP)

C-10 (S/N: 3CS1-UP)

C-12 (S/N: 2KS1-UP; 9SM1-UP)

C-15 (S/N: 6NZ1-UP)

C-16 (S/N: 7CZ1-UP)

Reference: Troubleshooting Guide, RENR2238, "Engine Speed/Timing Circuits Test" Refer to Step 2 and Step 3.

Repair kits for engine speed sensors are now available. The new kits are designed to improve the electrical connection for the engine speed sensors.

An intermittent engine speed signal will cause the ECM to log a 190-12 Loss of Engine Crank Sensor RPM Signal and/or a 64-12 Loss Of Engine Cam Sensor RPM Signal. The occurrence of these diagnostic codes generally has no effect on engine performance, although the diagnostics may be accompanied by a slight speed burp.

If an active or a logged 190-12 diagnostic code and/or a 64-12 diagnostic code is present in the ECM, proceed with the following steps:

1. Follow the procedures for troubleshooting that are in Troubleshooting Guide, RENR2238, "Engine Speed/Timing Circuits Test" Step 2 and Step 3.

2. If Step 2 and Step 3 are okay, the circuit for the engine speed sensor should be repaired. Refer to Table 1 for the correct repair kit. Special Instructions are included with the repair kits.

Note: If the engine is a C-10 or a C-12 engine with no active camshaft speed sensor diagnostic, repair the engine crankshaft speed sensor only. If the engine is a 3406E, C-15, or a C-16 engine with no active engine crankshaft speed sensor diagnostic, repair the engine camshaft speed sensor only.