REGULATOR-TEMPERATURE 3784327 - Caterpillar

Introduction
The problem that is described below does not have a known permanent solution. Until a permanent solution is known, use the solution that is identified below. The serial numbers of the affected units are in the process of being identified and the TIB will be updated once that information is available.Problem
There has been an issue identified in the field with the MS990C P/N 291-1913 Receivers that is used in Computer Aided Earthmoving Systems (CAES) and AccuGrade systems. This issue may show the symptoms outlined below. The problem stems from an out-of-specification (low temperature) component within the MS990C receiver. The CAES and AccuGrade systems have experienced repeated symptoms of this issue in the field. This issue may affect any CAES or AccuGrade system that is using MS990C receivers with the out-of-specification component.Symptoms
The receiver boots up in "Monitor mode":
On powerup, the receiver will boot up in "Monitor mode". When in this mode, the two outermost LEDs stay on and the middle LED flashes at 1 Hz.
The "diagnostics" screen in the AccuGrade display (CD700 and CD550A) shows "App. 0.10 required ?.?? 3.21" for the MS990C with the out-of-specification component:Notice the "MS990 - Right" Status and App. fields. Refer to Illustration 1.
Illustration 1 g01353265
The "About CAEultra" window for CAES shows "Not Available" for all the GPS information. This is also seen when the receiver is not connected. Refer to the Test below in order to confirm a suspected receiver. Refer to Illustration 2.
Illustration 2 g01353268
The "GPS" window for CAES shows "No GPS Position" at the top of the window. This is also seen when the receiver is not connected. Refer to the Test below in order to confirm a suspected receiver. Refer to Illustration 3.
Illustration 3 g01353279
The following symptoms may also be apparent with this problem:
All three LEDs (lights) on the MS990C flash on and off simultaneously at 0.5 Hz rate.
Receiver crashes unexpectedly during operation.Test Procedure
Remove the suspect MS990C from the machine.
Place the suspect MS990C in a freezer for two hours.
Remove the suspect MS990C from the freezer and place the receiver on the machine. (May also use the service cable 291-1384 Wiring Harness and a 12VDC-24VDC power supply to power up without a machine).
Once the power is applied to the suspect MS990C watch the LEDs for one of the below light patterns.
The two outermost LEDs stay on and the middle LED flashes at 1 Hz.
All three LEDs flash at approximately 0.5 Hz rate.
If the suspect MS990C demonstrated any of the above light patterns, the unit has the out-of-specification component.Solution
The issue that is described does not have a known Interim Corrective Action at this time. The serial numbers of the affected units are in process of being identified and the TIB will be updated once information is available. Information is also available through CPI issue 157974. Until an Interim Corrective Action or a Permanent solution is known, use the symptoms or test to help identify if the MS990C has the issue. If the MS990C is