Daniel Nardiello scored deep into stoppage time as Bury prevented Scunthorpe boss Russ Wilcox beginning his full-time reign with a win.
Sam Winnall tapped in to put the visitors 1-0 up at the break.
But after firing in a second from close range, the Iron striker was then sent off after a second booking for an overzealous celebration.
Chris Sedgwick fired home from inside the box before Nardiello latched onto Andy Procter's through-ball to level.
VIEW FROM THE DRESSING ROOM
Bury Manager David Flitcroft told BBC Radio Manchester:
"We really did want three points today. I said to the players at half-time, one thing you know I really wanted was a clean sheet, a 45-minute clean sheet.
"We stood firm for 37 minutes which is important and I was really disappointed that we didn't capitalise on our first-half performance.
"We're showing at times that lack of ruthlessness that has cost us all season really."
Scunthorpe United manager Russ Wilcox told BBC Radio Humberside:
"I'm absolutely gutted. As a group the dressing room in there feels like we've lost 3-0. We've managed the period where we're down to 10 men really well - OK they've thrown a few balls into the box but we've been brave, we've stuck bodies on the line, we've got blocks in, we've defended for our lives and we deserved the three points and I'm devastated for the lads.
"The only thing I've got for the players today is praise. I'm disappointed about the rule (for the sending off) but it's not the referee's fault, but for me it's something that needs to be looked in to. It's a joke.
"I still thought we did enough after the sending off to see out the game and pick up the three points."
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