De-Coupled Dynamic Rear Proportioning: Notes
De-Coupled Dynamic Rear Proportioning (DDRP) is a proportioning system to maintain vehicle stability during braking. In normal braking conditions, equal wheel speed should be maintained for efficient and balanced braking. In hard braking conditions, a vehicle requires relatively less brake force at the rear wheel due to the vehicle's weight transfer to the front. DDRP maintains desired brake pressure to the rear wheel by using the ABS rear inlet and outlet valve in order to provide efficient braking and vehicle stability. In the DDRP system, power to the rear hold valve solenoid is provided from the ignition. If the following fault conditions are existing, the red brake warning lamp will be illuminated.
- Two wheel speed sensors inoperative on same axle.
- Rear inlet solenoid is inoperative.
- Battery 2, motor input, short to ground.
- Battery 1, EBCM input, open or short to the ground.
- Motor ground open or short to battery.
- EBCM ground open or short to battery.
- Ignition open or short to ground.
De-Coupled Dynamic Rear Proportioning - Failure Modes
| Part | Hypothesized Failure | De-Coupled DDRP | ||
|---|---|---|---|---|
| ABS Warning Lamp | Brake Warning Lamp | DDRP Status | ||
| Sensor RF | Short or Open | ON | - | Degraded |
| Sensor LF | Short or Open | ON | - | Degraded |
| Sensor RR | Short or Open | ON | - | Degraded |
| Sensor LR | Short or Open | ON | - | Degraded |
| Two Sensor, Same Axle | Short or Open | ON | ON | Disabled |
| One Front and One Rear Sensor | Short or Open | ON | - | Degraded |
| Motor | Short to Ground - LOW Side | ON | - | Degraded |
| Short to Ground - HI Side | ON | - | Degraded | |
| Short to Battery - LOW Side | ON | - | Degraded | |
| Short to Battery - HI Side | - | - | None | |
| Motor Circuit Open | ON | - | Degraded | |
| Motor Stalled | ON | - | Degraded | |
| Front Apply Solenoids | Short or Open | ON | - | Degraded |
| Front Release Solenoids | Short or Open | ON | - | Degraded |
| Rear Apply Solenoids | Short or Open | ON | - | Degraded |
| Rear Release Solenoids | Short or Open | ON | ON | Degraded |
| System Relay | Open - Unable to turn ON | ON | - | Degraded |
| Shorted ON - Unable to turn OFF | - | - | None | |
| Battery 2 Motor | Short to Ground | ON | ON | Degraded |
| Open | - | - | Low Voltage | |
| Ground - Motor | Open or Short to Battery | ON | - | Enabled |
| Battery 1 - ECU, Solenoids | Open or Short to Ground | ON | ON | Disabled |
| Ground - ECU, Solenoids | Open or Short to Battery | ON | ON | Disabled |
| Ignition | Open or Short to Ground | ON | ON | Disabled |
| Brake Switch (Delphi System) | Not Applicable | - | - | Enabled |
| Brake Switch (Mando System) | Not Applicable | - | - | - |
| Serial Communication | Open or Short | ON | ON | Enabled |