No Bus 2002 Dodge Dakota 4.7

2002 Dodge DakotaI have 2002 Dodge Dakota. I was driving home and the cluster stopped working.  All the gauges bottom out and the dash lights came on and now it says No bus and 920,921,and 999 at the bottom left corner. And the AC stopped at the same time. Can you point me in the right direction?
Thank you


What you have is no communication between the instrument cluster and the other control modules in the vehicle. The truck uses a two wire communication system and if one of those wires goes out then the whole system is down. Most common is a mouse chewed through one of the bus wires on your truck and it needs to go to the dealership because they are the only ones who can properly diagnose a bus failure. It requires the use of a DRB III. Another cause may be from corrosion in the wires and or wiring harness connections.

Testing for codes 920, 921 and 999

Check in clean the connections at the underwood power distribution center disconnect the terminals clean and Henry tighten them also remove the fuses and the relays one at a time and reinstall them cleaning the terminals as you go,The BUS voltage originates from the IC. Begin by unplugging all of the modules that are on the BUS circuit, while monitoring the BUS voltage.
These include Powertrain Control Module , Central Timer Module, Controller Anti-Lock Brake , Overhead Console, Radio, Air bag Control Module . Leave the IC plugged in for this test.
When the BUS voltage returns to approximately 2.5 volts, the module that was disconnected last is the bad module, replace it

The BUS voltage can be tested at the Diagnostic Link Connector at pin 3 Violet/Brown and pin 11