CX28, CX31 and CX35 On-Highway Transmissions Power Train Electronic Control System Caterpillar

Illustration 1	g01303497

There are two types of outputs. There are driver outputs and sinking outputs. The driver outputs include the PTO Latching Output, Starter Interlock Output and the Backup Alarm. These outputs are capable of driving 2 Amps of current at battery voltage.

The sinking outputs include the Gear Indicator output. This driver is capable of 0.3 Amps.

If the replacement of a relay or a solenoid is larger than the original, meaning that the replacement has a higher amperage capability, then the ECU output may disable in order to keep from destroying the internal parts of the ECU components. A diagnostic trouble code will not be generated in this type of situation. The output will appear not to function.

Perform the following check:

• Turn the ignition switch OFF. Disconnect the replacement relay or solenoid. Instal a test lamp. Turn the ignition switch ON and activate the output. If the test lamp indicates that the output is functional, the replacement relay or solenoid must be replaced with a relay or solenoid that meets the origninal specifications. If it is necessary, a smaller relay or solenoid can be used in order to operate the larger relay or solenoid.

There are three outputs that are rated for driving relays or solenoids. These outputs are rated at 2 amps at the chassis battery voltage.

There are three additional low power drivers that are capable of 300 milliamps.

Note: Replacing a driver with one that is rated for a higher amperage may result in loss of functions. If a loss of a function results after replacing a driver or relay, ensure that the replaced driver or relay is properly rated.