I have a 2001.5 2500 Ram Automatic with the cummins Diesel, About a week ago the check gauge light came on, and the volt meter went to 0. So far I have :

- Checked the 140amp fuse which tests good.
- Had both batteries load tested, and as told they are AOK
- Replaced the Alternator
- Replaced the PCM
- Replaced the battery temp sensor
- Disconnected the grid heaters

I still have the same problem all grounds are clean and tight

Please help!

 

Might be a bad cluster, perform this test will check all gauges.

The instrument cluster actuator test will put the instrument cluster into its self-diagnostic mode. In this mode the instrument cluster can perform a self-diagnostic test that will confirm that the instrument cluster circuitry, the gauges, and the CCD data bus message-controlled indicators are capable of operating as designed. During the actuator test the instrument cluster circuitry position each of the gauge needles at various calibration points, illuminate each of the segments in the Vacuum-Fluorescent Display (VFD), and turn all of the CCD data bus message-controlled indicators on and off.

Begin the test with the ignition switch in the Off position.
Depress the odometer/trip odometer switch button.
While still holding the odometer/trip odometer switch button depressed, turn the ignition switch to the On position, but do not start the engine.
Keep the odometer/trip odometer switch button depressed for about ten seconds, until CHEC appears in the odometer display, then release the odometer/trip odometer switch button.
A series of three-digit numeric failure messages may appear in the odometer display, depending upon the failure mode. If a failure message appears, refer to the Instrument Cluster Failure Message chart for the description and proper correction. If no failure message appears, the actuator test will proceed as described in Step 16. INSTRUMENT CLUSTER FAILURE MESSAGE
Message Description Correction
110 A failure has been identified in the cluster CPU, RAM, or EEPROM. 1. Replace the faulty cluster.
900 The CCD data bus is not operational. 1. Check the CCD data bus connections at the cluster.

2. Check the cluster fuses.

3. Check the CCD data bus bias.

4. Check the CCD data bus voltage.

5. Check the CCD data bus terminations.

920 The cluster is not receiving a vehicle speed message from the PCM. 1. Check the PCM software level and reflash if required.

2. Use a DRBIIIŽ scan tool to verify that the vehicle speed message is being sent by the PCM.

921 The cluster is not receiving a distance pulse message from the PCM. 1. Check the PCM software level and reflash if required.

2. Use a DRBIIIŽ scan tool to verify that the distance pulse message is being sent by the PCM.

940 The cluster is not receiving an airbag lamp-on message from the ACM. 1. Check the CCD data bus connections at the ACM.

2. Check the ACM fuse.

950 The cluster is not receiving an ABS lamp-on message from the CAB. 1. Check the CCD data bus connections at the CAB.

2. Check the CAB fuse.

999 An error has been discovered. 1. Record the failure message.

2. Depress the trip odometer reset button to continue the Self-Diagnostic Test.

 

Dam n, that's a lot of parts. Do you have any codes? Have you measured voltage output across the battery terminals when this happens? Have you checked the connection at the alternator? Dis you bench test the alt before installing? Did you bench test the old alternator before turning it is as a core?