Fresh electrical problems prevented the McLaren-Honda development car from running in the morning session of the second day of post-season Formula 1 testing in Abu Dhabi on Wednesday.

The MP4-29H was late out of the garage in Tuesday’s test, thanks to electrical issues, and completed just two full laps when it did appear due to a problem with the data-logging and fuel systems.

McLaren racing director Eric Boullier said fresh electrical problems discovered just before the start of Wednesday’s first session have prevented the car from running again so far.

“It’s very difficult to understand,” he told AUTOSPORT.

“Overnight it went very well – a couple of issues, but things we could unplug and run without.

“We fired up at six o’clock and everything was fine; the car was on the ground ready to run at eight-thirty, driver in.

“We fired up the car to go at nine and then something went wrong, which obliged us to take off all the battery pack again.”

Boullier said McLaren and Honda had not yet been able to fully trace the source of the problems, which he described as “different to yesterday”.

“Electricity is complicated – you plug in and something goes wrong, you fix it, re-plug and something goes wrong somewhere else,” Boullier added.

“We are just chasing, but I understand we are closing in on the problems.

“We will run as soon as we can, but it’s a very sensitive area and a very high level voltage, so you need to be careful about what you are doing.

“It takes time unfortunately, but I prefer this to happen here than in Jerez.”