De-Coupled Dynamic Rear Proportioning (DDRP)
De-coupled dynamic rear proportioning (DDRP) is a proportioning system to maintain vehicle stability during braking. In normal braking condition, equal wheel speed should be maintained for efficient and balanced braking. In hard braking conditions, a vehicle requires relatively less brake force at rear wheel due to vehicle's weight transfer to the front. DDRP maintains desired brake pressure to the rear wheel by using the antilock brake system (ABS) rear inlet and outlet valve in order to provide efficient braking and vehicle stability. In the DDRP system, the 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 inoperative
- Battery 2, motor input, short to ground
- Battery 1, electronic brake control module (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 (DDRP) Failure Modes
| Part | Hypothesized Failure | De-Coupled DRP | ||
|---|---|---|---|---|
| ABS Warning Lamp | Brake Warning Lamp | D-DRP 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 |
| 2 Sensors, Same Axle | Short or Open | ON | ON | Disabled |
| 1 Front and 1 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 GND | ON | ON | Degraded |
| Open | - | - | Low Voltage | |
| Ground, Motor | Open or Short to Batt | ON | - | Enabled |
| Battery 1, EBCM, Solenoids | Open or Short to GND | ON | ON | Disabled |
| Ground, EBCM, Solenoids | Open or Short to Batt | ON | ON | Disabled |
| Ignition | Open or Short to GND | ON | ON | Disabled |
| Brake Switch | Not Applicable | ON | - | Enabled |
| Serial Communication | Open or Short | ON | ON | Enabled |