Both defences had dominated for 90 minutes, but with the game drifting towards a goalless draw, striker Morrell struck with his fourth goal of the season.
Player-boss Gary McAllister robbed the otherwise impeccable Wigan defender Jackson on the edge of the area and played in substitute Claus Jorgensen. His shot was blocked, but Morrell gleefully fired home the rebound and Wigan looked to be heading for only their second defeat of the season.
But the villain Jackson turned hero just seconds later when he was on hand to turn the ball home after City keeper Scott Shearer spilled a Neil Roberts volley onto the post.
Wigan deserved no less after having Peter Kennedy controversially sent off in the second half following successive challenges on Graham Barrett that were both deemed bookable.
Andrew Whing and Barrett peppered the Wigan goal with long-range efforts straight after the restart before Bullard fired in two in quick succession from 20 yards - both fizzing over Shearer's bar.
McAllister replaced Yazid Mansouri with Jorgensen just before the hour and Wigan wasted a gilt-edged chance minutes later when Nathan Ellington blazed over from six yards.
Lee McCulloch's last contribution was a booking for his challenge on Barrett that saw him hobble off and replaced by Jason Jarrett, but it did little to disrupt the visitors' well-organised ranks.
Kennedy became the third Wigan player to be booked following a challenge on Barrett and he soon saw red - somewhat harshly - for a second bookable offence on the same player shortly after Geoff Horsfield had been replaced by Roberts.
In the first period it was Wigan's football that caught the eye. Keeping the ball down, their slick inter-play threatened to carve Coventry open.
On 17 minutes recent signing Geoff Horsfield nearly did just that, hitting the post with a snapshot from 18 yards and then firing the rebound straight back onto the woodwork as Lady Luck smiled down on Shearer.
Ellington then curled a 25-yard free-kick straight into Shearer's arms following Muhamed Konjic's clumsy challenge and the home side responded when McAllister fired straight at John Filan with a free-kick of his own from similar distance.
Adebola headed weakly at Filan again from Morrell's cross but the Sky Blues were being eclipsed by Paul Jewell's early pacesetters, with Bullard - booked for his foul on Barrett - pulling the strings in midfield.
Coventry began to press as the interval approached and from McAllister's corner Konjic connected on the volley from the edge of the area, but his goalbound shot was blocked by a melee of Wigan defenders.
Another bullet shot, this time from Youssef Safri from McAllister's corner, was also charged down and Horsfield fired in a long-range volley that Shearer did well to hold but both defences looked comfortable until the dying moments.
Report from Ananova.
