Without 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.
^ Two opens in the 800 CKT.
^ Internal BCM or IPC fault.
^ Open in ECCP ground circuit.

TEST DESCRIPTION
Numbers below refer to circled numbers on the diagnostic chart.
1. Checks to see if the ECCP has lost data communication along with the IPC.
2. Since the IPC has lost data communications, shorting pin M at the ALDL connector should not remove data communications from the ECCP as well. If it does, the IPC is receiving data but is unable to communicate due to a poor connection or an internal problem.