With CRT/DID

CIRCUIT DESCRIPTION
The IPC indicates a loss of serial data communication by displaying only the message "ELECTRICAL PROBLEM." All other segments are blank. If the display is fully illuminated and an "ELECTRICAL PROBLEM" message is also displayed, enter diagnostics and proceed to the appropriate code chart. Do not use CHART A.

Loss of serial data communications can occur for the following reasons:
^ Short to ground anywhere in the 800 CKT.
^ Short to voltage anywhere in the 800 CKT.
^ Double open in the 800 CKT.
^ Internal BCM or IPC fault.

TEST DESCRIPTION
Numbers below refer to circled numbers on the diagnostic chart.
1. If the climate control page is accessible, the CRTC/DIDC is receiving ignition power and should be capable of communicating with the BCM.
2. Checks to see if the CRTC/DIDC has lost communication with the BCM.
3. Checks to see if the IPC has lost communication with the BCM as well.
4. Checks continuity of the data line (CKT 800). Since the data line is a loop, resistance around it should be close to 0 ohms.
5. Checks for a short to ground on the data line.
6. Checks voltage on the data line under normal operating conditions. Normal data line voltage is between 1 and 5 volts and continually fluctuating. A fixed voltage or a voltage above 5 volts indicates a problem on the data line which may cause the entire communications network to be inoperative.