Chart B, Odometer Displays Error (LOS Of Serial Data) (REATTA & Riviera)

1992 Saturn SC StandardSECTION Chart B, Odometer Displays Error (LOS Of Serial Data) (REATTA & Riviera)
Fig 1: Chart B - Wiring Schematic (Reatta & Riviera)
G91I07760Courtesy of GENERAL MOTORS CORP.

IPC indicates loss of serial data communication by displaying ERROR in odometer and illuminating ELECTRICAL PROBLEM telltale light. Loss of serial data communications can occur for the following reasons:

  • Short to ground somewhere in circuit No. 800
  • Short to voltage somewhere in circuit No. 800
  • Two opens in circuit No. 800
  • Internal fault in BCM or IPC
  • Open in ECCP ground circuit
    NOTE: Test numbers refer to numbers on diagnostic chart.
    1. This steps checks if BCM is awake and functioning. If it is not, use chart B-1 to isolate fault.
    2. This step checks if ECC head has lost data communication along with IPC.
    3. Code B556 indicates IPC EEPROM error. Odometer will display ERROR, but diagnostics will be accessible.
    4. Since IPC lost data communications, creating an open in data line at ALDL connector should remove data communications from ECCP as well. If not, IPC is receiving data but is unable to communicate due to poor connection or internal problem.
    5. This test indicates data line shorted to ground.
    6. This test indicates data line functioning properly, but with multiple opens isolating IPC and ECCP from BCM.
    7. This test indicates data line shorted to voltage.
Fig 2: Chart B - Troubleshooting Diagram (Reatta & Riviera)
G91A07761Courtesy of GENERAL MOTORS CORP.
RENDER: 1.0x

NO RELATED

Recommended Tools & Savings

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Affiliate disclosure: We may earn a commission at no extra cost to you.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.