U1500
DTC U1500
CIRCUIT DESCRIPTION
This DTC indicates an internal fault and is set within the vehicle communication interface module (VCIM). No external circuits are involved.
DTC DESCRIPTOR
This diagnostic procedure supports the following DTC:
DTC U1500 Inter-Device Dedicated Bus Malfunction
This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description in Vehicle DTC Information. DTC Symptom Description
CONDITIONS FOR RUNNING THE DTC
The microprocessor runs the program to detect an internal fault during module power up and every 10 seconds thereafter until the module re-enters the sleep mode.
CONDITIONS FOR SETTING THE DTC
The VCIM detects an internal communication malfunction.
ACTION TAKEN WHEN DTC SETS
- The OnStar(R) status LED turns red.
- The vehicle is unable to connect to the OnStar(R) Call Center.
CONDITIONS FOR CLEARING THE DTC
- A current DTC clears when the malfunction is no longer present.
- A history DTC clears after 50 malfunction-free ignition cycles.
DIAGNOSTIC AIDS
- The diagnostic procedure used for DTC U1500 in OnStar(R) systems with single module generations of OnStar(R) differ greatly from previous generations with 2 modules. While these older generations denoted a failure of the 3 wire bus between the modules by setting a U1500, single module OnStar(R) systems use this DTC to denote an internal module failure. The determination of whether a 1 or 2 module generation of OnStar(R) is used should be confirmed. Refer to OnStar Description and Operation.
- This DTC may be stored as a history DTC without affecting the operation of the module. If stored only as a history DTC and not retrieved as a current DTC, do not replace the VCIM.
- If this DTC is retrieved as both a current and history DTC, replace the VCIM.
TEST
