Haas F1 team suffers brake-by-wire problems in Barcelona testing

Grosjean caused three flags over the course of the day, twice ending up in the gravel but avoiding any major damage.

"It's been a tough day, yes," said team principal Gunther Steiner.

"We are working a lot on the brake-by-wire system.

"It was difficult for him to drive and that's why he went off, it was all related to that development.

"It's Ferrari's system but we need to develop it to our needs.

"If we need to develop it, we cannot use their data to develop it.

"It's not a hardware issue. It's just an electronic issue."

Grosjean, who suffered similar problems with the system when at Lotus in 2014, said: "It's a very complicated system.

"The car is going a bit quicker this week and we are finding more issues on that system.

"I think it will be solved by Melbourne. Hopefully for tomorrow we have the fix.

"We really need to get on top of things because that is hurting us in term so preparation, performance and setting up the car but we're on it."

Grosjean's third stoppage of the day, near the end of the session, was a result of him hitting the kerbs.

"The engine switched off because he hit the kerbs so hard," said Steiner.

"That was the reason. He had a big off on the kerb and then stopped."

Steiner added the team has "quite a lot of work" to do as the floor was damaged in each of the three incidents.

Though he admitted the team has no more spares, he was confident it could "fix what we have got".