Speed Reads High All the Time or Range Display Shows "--" All the Time

1) Check position of English/Metric switches. Check for open wiring harness from DFI computer. Check for presence of serial data line signal from DFI computer. Repair or replace wiring harness.

2) Check operation of ECC, EG and MPG head for proper operation. If necessary, replace DFI computer. Resetting average MPG function on MPG head when a large instantaneous "MPG" is displayed may be necessary.