Usage:
G3608 (4WF),
G3612 (1YG),
G3616 (4CG) ENGINES
Problem:
During the starting sequence of these engines, the Magneto Shutoff Relay (MSR) contacts can chatter when energized. this chatter results in a noise burst on the Ignition Pulse wiring between the Caterpillar Ignition System (CSI) and the Engine Timing Control (TCM). The noise burst disables the Ignition Pulses with the TCM and the indicated timing locks onto 0.0 degrees. These conditions will generate a "326-09 No Magneto Interface Signal" shutdown fault code and the engine will be kept from starting.
Solution:
To resolve this situation, an additional relay (121-6159 Relay Module) can be installed into the Engine Supervisory System (ESS) panel. The purpose of the relay is to provide an alternate grounding path around the MSR during the cranking cycle, thus protecting the ignition pulse signal from the noise burst created when the MSR is energized. The contacts of the new relay are closed when the engine is started, and the MSR is energized. The contacts remain closed until the engine speed reaches the crank termination speed of 250 rpm. The crank termination circuit of the Status Control Module (SCM) is used to power the new relay on and off. The normally closed contacts are used on the new relay.
The protection that is provided by the MSR is not compromised with the addition of the new relay. The MSR contacts will open, and shutoff the ignition system during an over speed and emergency stop conditions. This is because the contacts of the new relay will not close until the engine speed is reduced to 0 rpm.
Relay Installation Procedure
The new 121-6159 Relay Module should be installed into the ESS Panel as follows:
- 1. The new relay will mount to the DIN rails in the ESS Panel. Locate an available position.
- 2. Install the new relay wiring as follows:
- a. From +Battery (T352) to +CTR (T375).
- b. From -CTR (T374) to the coil side of the new relay.
- c. From coil ground side of the new relay to -Battery (T354 or T353).
- d. From (T526) to the normally closed contact of the new relay and from the downstream side of the normally closed contact to -Battery (T354 or T353).
- 3. Insure that the new wiring is properly routed through the ESS Panel to eliminate the possibility of damaged wires.
COPYRIGHT 1998 CATERPILLAR ALL RIGHTS RESERVED