DTC 83

Fig. 208 Code 83: Brake Fluid Differential Pressure Fault (Part 1 Of 2).:

Fig. 208 Code 83: Brake Fluid Differential Pressure Fault (Part 2 Of 2).:

DTC 83: Brake Fluid Differential Pressure Fault:

Circuit Description:
The brake fluid differential pressure circuit monitors the pressure in the brake system. If the pressure becomes significantly different between the two brake hydraulic circuits, as indicated by the brake differential pressure switch, the ABS/TCS system is disabled. This is done to prevent introduction of air into the brake system. The diode is used to prevent disabling ABS/TCS if illumination of the red "BRAKE" warning lamp occurs because of application of the parking brake.

DTC 83 will set and the "ANTI-LOCK" and "TRACTION CONTROL" lamps will illuminate if CKT 1684 is low (grounded).

Test Description:
Number(s) below refer to circled number(s) on the diagnostic chart.
1. Checks for proper brake fluid level in the master cylinder reservoir.
2. Checks for illumination of the red "BRAKE" warning lamp for reasons other than parking brake engagement.
3. Checks for brake pressure switch stuck closed.
4. Checks for short from CKT 1684 to chassis ground.
5. Adds fluid, noted to be low in Step 1, then checks for DTC reset.
6. Checks for continuing DTC reset after checks in Steps 1-4.
7. Checks for DTC reset when parking brake is engaged, likely due to a malfunctioning diode.
8. Checks for parking brake switch stuck closed.
9. Checks for short to ground in parking brake switch CKT 33.
10. Replaces malfunctioning diode found in Step 7 or Step 10, then checks for DTC reset. If DTC resets, the EBTCM is determining there is a problem in CKT 1684 and related circuitry when there is not.

Diagnostic Aids:
It is very important that a thorough inspection of the wiring and connectors be performed. Failure to carefully and fully inspect wiring and connectors may result in misdiagnosis, causing part replacement with reappearance of the malfunction.