Quick diagnostic: MID 130 PID 37

Initial Setup & Triage

DTC Check:

• FMI 3 / FMI 5: Electrical fault. Replace the transmission air pressure sensor first. (Refer to ECU repairs – TECU).

• FMI 0 / FMI 1: Pressure out of range. Continue to diagnostic below.

Specs: High >1000kPa / Low <650kPa. Optimum: ~850kPa.

Step 1: Check Live Data

Connect diagnostic PC. Navigate to Transmission Test > Prerequisites. With ignition ON, check the transmission air pressure reading.

Step 1: Check Live Data

Connect PC > Transmission Test > Prerequisites. Check transmission air pressure with ignition ON.

Step 2: Zero-Point Test

Remove TECU air inlet pipe. Does the PC reading drop to 0?

Step 3: Monitor Build-Up

Refit pipe, start engine, and monitor pressure until air system purges.

What is the reading at purge?

Step 4: Air Dryer Calibration

Note: Electronic Air Dryers only. Perform Tech Tool > Calibration > Air Dryer Calibration.

Is pressure still low?

Step 5: Manometer & Sieve Test

Connect manometer to TECU supply side. If pressure matches PC but is low, check the Sieve/Filter behind the brass inlet fitting for clogs.

Which dryer system is fitted?

Step 6: Electronic Dryer Check

Check Brakes > Pneumatic System Status. Build air until purge (~950kPa).
If it fails to purge and hits safety valve, see V2 Air Dryer Guide.
If it purges normally but pressure is off, calibrate via Tech Tool.

Step 7: Mechanical Dryer Adjustment

Monitor primary tank pressure. Adjust screw on dryer (Clockwise = Increase) until purging at ~950kPa.

Step 8: Tank & One-Way Valve

Remove supply pipe to transmission tank. Inspect the One-Way Valve for sticking (oil/water/dust). Verify tank pressure via the test port using a manometer.

Step 9: 4-Way Protection Valve

Adjust 4-Way valve (Follow pipe from trans tank). Clockwise = Increase. If no change, check primary supply for restrictions or replace valve.