Travellers faced delays on Wednesday afternoon after trains were stopped between Preston and Bolton.
A problem with equipment between Chorley and Blackrod meant signals were not working correctly early in the morning.
A spokesman for Northern Rail said engineers fixed the issue and trains were running as normal by 7.30am.
But the fault recurred later that morning and engineers needed to replace cable.
Trains between Preston and Bolton were replaced by buses in both directions, extending journey times by up to 40 minutes.
The Northern Rail services between Blackpool North and Manchester Victoria, and Preston and Hazel Grove, were affected, as well as First TransPennine Express services between Preston, Blackpool North, Lancaster and Manchester Airport.
However, one train an hour was running in each direction between Blackpool and Manchester Victoria.
It was hoped the repairs could be made before the afternoon rush hour.