Chart B-2 CRTC or Data Problem

Chart B-2:

Data Circuit:

TEST DESCRIPTION: Numbers below refer to circled numbers on diagnostic chart.

1. The "ELECTRICAL PROBLEM" telltale in the IPC will come "ON" if the IPC or CRTC has lost data. Since diagnostics cannot yet be accessed to isolate the fault, noting the odometer display will verify if all communication is lost or if the IPC is receiving data from the BCM. If the IPC receiving data the odometer displays actual miles, not error.

2. Because the IPC and BCM can exchange data, the data line cannot be shorted. Since the IPC odometer displays actual miles the reason the "ELECTRICAL PROBLEM" telltale is "ON" is because the CRTC, not the IPC, has lost data. In order for this to occur, CKT 800F must be OK and there must be two opens in the data line, one on either side of the CRTC isolating it from the BCM, or the CRTC is at fault. To verify the integrity of the data line between the ALDL and the IPC, remove the ALDL cover and jumper the data line to ground. If the data line is OK, the odometer will display error as jumpering the data line to ground will stop all communication.

3. If the odometer did not display error, there is an open in the data between the ALDL and the CRTC along with another open between the CRTC and the BCM, or the CRTC is bad or if there are two opens, reconnect the ALDL cover and ground the data line at the CRTC. If the data line is open, the IPC will continue to display actual miles.