Chart C, Color CRT Unable To Control ECCP (CRT Equipped TORONADO & TROFEO)

IPC indicates loss of serial data communication by displaying the message ELECTRICAL PROBLEM. All other segments are blank. If display is fully illuminated and ELECTRICAL PROBLEM message is displayed, enter diagnostics and proceed to appropriate code chart. DO NOT  use CHART A. See Figure.

Loss of serial data communications can occur for the following reasons:

• Short to ground anywhere in circuit No. 800
• Short to voltage anywhere in circuit No. 800
• Two opens in circuit No. 800
• Internal BCM or IPC fault
  NOTE: Test numbers refer to numbers on diagnostic chart.
  1. If climate control page is accessible, CRTC is receiving ignition power and should be capable of communicating with BCM.
  2. This step checks to see if CRTC has lost communications with BCM.
  3. This step checks to see if IPC has lost communication with BCM also.
  4. This step checks continuity of the data line (circuit No. 800). Since data line is a loop, resistance around it should be close to zero ohms.
  5. This step checks for short to ground on data line.
  6. This step checks voltage on data line under normal operating conditions. Normal data line voltage is a continual fluctuating between 1.0 and 5.0 volts. Voltage above 5.0 volts or non-fluctuating voltage indicates a problem in data line causing entire communications network to be inoperative.

Fig 1: Chart C - Troubleshooting Diagram (CRT Toronado & Trofeo)

Courtesy of GENERAL MOTORS CORP.