Martin McIntosh's last-minute equaliser leaves Scunthorpe on 32 points - four above Blackpool, who occupy the final drop spot, while the Terriers move up to fourth
Swansea reclaimed top spot as Leon Knight marked his debut with a spectacular hat-trick.
The £125,000 signing from Brighton scored within five minutes, and had claimed the matchball with less than half an hour on the clock as the Swans beat MK Dons 3-1 at the Liberty Stadium.
Blackpool boosted their hopes of avoiding relegation with a 1-0 win over Oldham, Lewis Gobern got the only goal of the game.
Gillingham's push for survival slipped up at Barnsley, as they lost 1-0, with former Iron Alan Knill marked his first game in charge of Rotherham with a 1-1 draw with Port Vale.
And the Millers could have claimed all three points had Michael Keane not seen his penalty kick saved.