Hydraulic Impulse Storage (HIS)
WARNING: This page is about a different car, the 2017 Jaguar XJ, 2016 Jaguar XJ, 2015 Jaguar XJ, 2014 Jaguar XJ, and 2013 Jaguar XJ. However, it is still accessible from the selected car via links, so may be relevant.
| ITEM | DESCRIPTION |
|---|---|
| 1 | Hydraulic Impulse Storage (HIS) accumulator |
| 2 | Connection to transmission casing |
| 3 | Electrical connector |
Following an ECO stop, the vehicle must be able to restart and drive away within a very short period of time, less than 400ms from the point of the engine starting. The transmission must also be able to react in this time. When the engine is not running the ATF pump is not operating and fluid pressure decays to zero and the brake and clutch elements unlock. When the engine is re-started, the transmission ATF pump requires approximately 800ms to provide the fluid volume and pressure required to engage the shift elements. The HIS (Hydraulic Impulse Storage) system overcomes this by providing fluid pressure quickly to the shift elements during the engine start process within the engine start time parameter.