COVER GP-VALVE MECHANISM 1503135 - Caterpillar

Package Generator Sets With Electronic Modular Control Panels (EMCP)Interchangeability problems exist between certain change levels of the 8T9881 Control Group [(ECM) Engine Control Module] and the 9W2126 Relay Module used in the 7C1000 and 9Y1400 Electronic Modular Control Panels (EMCP ). See Illustrations 2 and 3. If a Change Level 5 relay module is used with a Change Level 1 or 2 Engine Control Module (ECM), the ECM can not be powered due to an internal wiring change in the Change Level 5 relay module.
The easiest way to determine which 9W2126 Relay Module can be used on which 8T9881 Control Group is to count the wires in the internal ECM harness which goes to the relay module internal connector shown in Illustration 1. If this harness has 11 wires, all relay modules except those marked 9W2126-5 can be used on the 8T9881 Control Group. (See Illustration 2 for the location of the part number and change level marking on the 9W2126 Relay Module.) If the connector has 10 wires, any change level of the 9W2126 Relay Module can be used on the 8T9881 Control Group.
Another method of determining which 9W2126 Relay Modules can be used on the 8T9881 Control Group is provided in the chart. The chart lists the change levels of the 8T9881 Control Group and the 9W2126 Relay Modules which may be used with each of these ECM change levels.
Illustration 1. Internal harness in the ECM. The harness has either 10 or 11 wires depending on the change level of the ECM. This harness must be disconnected in order to remove the 9W2126 Relay Module.
Illustration 2. Location of the part number and change level markings on the 9W2126 Relay Module. The change level follows the dash behind the part number.
Illustration 3. Location of the part number and change level markings on the 8T9881 Control Group. The change level follows the dash behind the part number. The 8T9881 Control Group must be removed from the front panel of the 7C1000 EMCP in order to view the part number and change level.