Question

is this sentence run-on or have grammar issues?

Benjamin had thought it was a good idea to use the map at the back of the car when his phone died

Answer 1

It’s not a run-on sentence and it’s grammatically acceptable, but it’s slightly awkward/ambiguous because of tense and attachment of the clause "when his phone died."

Issues:
- Using past perfect ("had thought") without a clear reference point makes it sound like the thought happened before some other past event, which isn’t stated.
- It’s unclear whether "when his phone died" modifies "thought" or "use the map."

Clearer alternatives:
- Benjamin thought it was a good idea to use the map at the back of the car when his phone died.
- When his phone died, Benjamin thought it would be a good idea to use the map in the back of the car.
- Benjamin had thought it would be a good idea to use the map in the back of the car before his phone died.

Choose the version that matches the intended sequence (whether the thought preceded the phone dying or happened when/after it died).