HEAD 1334046 - Caterpillar

The harness code for the Caterpillar Monitoring System must match the application in order to function properly. If the harness code does not match the application, the following problems may occur:
loss of event notification
incorrect data displays
incorrect gauge needle positions
activation of diagnostic codesGenerally, once an engine is put into service there is no reason to change the harness code. During installation, the customer may decide to install optional sensors or optional gauges that were not initially ordered with the engine. Changing these components may require a different harness code.Check the current selection for the harness code and compare the current harness code with the description in Systems Operation, "Quad Gauge Module". Determine if the harness code is correct for the application.There are six pins on the back of the Caterpillar Monitoring System that are used to select the harness code. The pins are grounded or the pins are left open in various combinations for each application. The pins that are grounded are connected to the negative battery terminal block ("TB-2"). The negative battery terminal block ("TB-2") is located on the inside of the Instrument Panel. On the wiring schematic, the negative battery terminal block is labelled as "TB-2".Because of the large number of wires that are located on the inside of the Electronic Instrument Panel, determining the pins that are connected to the ground becomes difficult to do visually. There are two accurate methods for determining the harness code.
Harness Code Mode 5 Display (not available on all versions of the Caterpillar Monitoring System)
A multimeter may be used to check the harness code that is located on the Caterpillar Monitoring Systems without Mode 5.Note: If a ground wire is connected to "pin A", the harness code pin is not necessarily grounded. The other end of the wire may be tied to the harness and the wire may not be connected to "TB-2". This procedure is done so that the same wiring harness can be used during manufacturing regardless of the harness code.Procedure For Checking The Harness Code Selection
Check The Harness Code Selection Of The Caterpillar Monitoring System.
For 153-1929 Engine Monitoring Control (Caterpillar Monitoring System) and earlier modules, proceed to 5.
For 155-8653 Engine Monitoring Control (Caterpillar Monitoring System) and newer modules, turn the Engine Control Switch (ECS) to the COOLDOWN/STOP position.
In order to check the harness code, use Harness Code Mode 5. For more information about Harness Code Mode 5, see Systems Operation, "Harness Code Mode". STOP.
For the 153-1929 Engine Monitoring Control and earlier Caterpillar Monitoring Systems, use a multimeter to check for continuity between the pins for the harness code and Terminal Block 2 (TB-2). Do NOT rely on a visual inspection.
The pins that determine the harness code are located on the back of the Caterpillar Monitoring System. The harness code is identified by certain pins of the 40 pin connector. pin 31, pin 3, pin 21, pin 22, pin 16 and pin 6.
If a 7x-1708 Multimeter Probe (Red) or a 7x-1709 Multimeter Probe (Black) is available, the continuity check