Your COMPUSHIFT II offers a display mode that presents a collection of valuable readouts on one screen.

TACH 8000  MPH   100
GEAR   A1  TCC    ON
TEMP  185  BATT 12.1
TP     85  PRB    90
Label Meaning
TACH Engine speed in RPM
GEAR Transmission gear (see GEAR note below)
BATT Battery voltage applied to COMPUSHIFT II in volts
TP Throttle position
MPH Vehicle speed
TCC Status of the torque converter clutch
TEMP Transmission temperature
PRB Transmission hydraulic pressure as a percentage of maximum available pressure (see PRB note below)

The “PRB” item represents the current shift pressure as a percentage of available hydraulic pressure. The internal pressure regulator that’s part of the hydraulic pump assembly sets the minimum and maximum available pressure in the transmission. COMPUSHIFT II can set the pressure to be anywhere between the minimum and maximum set by the pressure regulator. When COMPUSHIFT II commands minimum pressure, this is displayed as 0%; maximum pressure is displayed as 100%. To see absolute hydraulic pressure, you must attach a pressure gauge to the test port on the transmission.

Regarding GEAR:

  • If you use Switch-Shift controls (paddles or pushbuttons) to select your gear, the gear indicator is prefaced by an “S” (example: GEAR S1).
  • When the automatic transmission is on control of shifting, the gear indicator is prefaced by an “A”, as shown (example: GEAR A1).
  • In manual mode, the gear indicator is prefaced by an “M” (example: GEAR M1).
  • If you have a four-wheel-drive vehicle, and the transfer case is in “low,” the display will show an “L” after the gear indicator (example: GEAR 1L).

 

The GEAR indicator may not read correctly until the engine is running. This is because some transmissions (notably GM) use hydraulic pressure to sense gear-lever position. Without the engine running to generate hydraulic pressure, the indicator can be incorrect. This is not a fault in your COMPUSHIFT II.