It's hard to say what's wrong without hooking up a factory san tool !
The instrument cluster is a configurable, hybrid electronic cluster (HEC) that contains a microprocessor, gauges, indicator lamps, and internal circuitry. The instrument cluster is non-repairable, with the exception of the instrument cluster lens, the warning bulbs, and the transmission range selector. The instrument cluster uses hardwired circuitry, the controller area network (CAN), and universal asynchronous receiver transmitter (UART)-based protocol (UBP) communication networks. Communication using the CAN uses data transmitted and received between the instrument cluster, the trailer brake control (TBC) electronic control unit, the powertrain control module (PCM), and the anti-lock brake system (ABS) module. Communication using the UBP network uses data transmitted and received by the instrument cluster, the vehicle security module, and the electronic automatic temperature control (EATC). For additional information regarding the communication network, refer to Section 418-00 .
It is very important to understand:
- where the input originates.
- all the information necessary in order for a feature to operate.
- which module(s) receive(s) the input or command message.
- whether the module which received the input controls the output of the feature, or whether it outputs a message over the CAN or UBP network to another module.
- which module controls the output of the feature.
The instrument cluster carries out a display prove-out to verify that the warning/indicator lamps and monitored systems are operating correctly. The safety belt warning indicator proves-out for 65-seconds or until the safety belt is fastened. The malfunction indicator lamp (MIL), and the wait to start indicator (diesel engines) illuminate continuously until the engine is started and operating normally. When the ignition switch is turned to the ON position with the engine off, the following indicators illuminate for 3 seconds:
The odometer and trip odometer are viewed through the message center in the integrated circuit display on message center clusters or in the integrated circuit display on base clusters. The odometer is tamper-resistant and accumulates and registers up to one million kilometers in metric mode or one million miles in English mode, based upon rolling count data sent from the PCM over the communication network. The trip odometer is resettable and accumulates and registers up to 9,999 kilometers or 9,999 miles.
Does the speedometer work ?