Hard starts when cold. on 2001 Ford F-250 Super Duty

My truck starts hard when it's cold out, someone suggested it might be the glow plug modulator. Could this be the problem rather than the glow plugs. If so how much could I expect to pay for this? Tom

Asked by for the 2001 Ford F-250 Super Duty
The module will usually set a code when it fails. Are you getting a check engine light?

The plugs probably need replaced. However, hard starts can be caused by oil condition, fuel injector wear, and so on.