Automotive Service Excellence (ASE) A6 Electrical/Electronic SystemsGauges, Warning Devices, and Driver Information Systems Diagnosis and RepairHard
A technician is diagnosing a complaint of an inoperative driver information display (DID) on a vehicle equipped with a Multi-Information Display (MID). The display is completely blank. All other dashboard functions, including the radio and climate control, are working. A scan tool reports no communication with the MID module. What is the most likely cause?
- AAn open circuit in the data lines between the MID and the instrument cluster.
- BA power supply issue to the MID module.
- CA short to ground in the CAN bus wiring.
- DA faulty instrument cluster.
Show answer & explanationAnswer & explanation
Correct answer: B. A power supply issue to the MID module.
If the MID module has no communication and is completely blank, but other modules on the CAN bus (radio, climate control) are functioning, it points to a localized issue with the MID module itself. A lack of power supply is a common reason for a module to be inoperative and unable to communicate.
Why the other options are wrong
- A. An open circuit in data lines specifically between MID and instrument cluster might still allow the MID module to communicate on the main CAN bus, but if there's 'no communication with MID module' at all, power is a more fundamental issue.
- C. A short to ground in the CAN bus wiring would likely affect communication with multiple modules, not just the MID, and could disrupt other functions.
- D. A faulty instrument cluster might affect the display, but the 'no communication with MID module' suggests the module itself isn't powered or communicating, rather than just the cluster's ability to display its data.
Module No Communication/Blank Display
When a specific module (like a driver information display) is completely blank and shows no communication via scan tool, while other modules function, a power supply issue to that specific module is a primary suspect.
- Check power (fuses) and ground first.
- 'No communication' implies the module is off or severely faulty.
- Localized issue, as other modules function.
Memory trick: MID blank, no talk: Check the 'POWER' cord, it might be 'UNPLUGGED'.