The Rail, Maritime and Transport union (RMT) will escalate the action from Sunday after train ticket examiners voted to join conductors in the next series of stoppages.
Their involvement will increase the number of trains cancelled from some 50 per cent to 89 per cent.
The only trains due to run will be hourly services on six routes in the Glasgow area, which will end by mid evening.
These account for just 122 of the normal 1,090 services scheduled.
They will operate between Glasgow and Ayr, Gourock and Wemyss Bay, and between Airdrie and both Balloch and Helensburgh.
The action follows walkouts by conductors over the last five Sundays, which left most passengers outside the Glasgow area with no trains.
RMT members are taking action over ScotRail refusing to increase overtime payments by half for working on days off.
They want parity with drivers, who are continuing to win higher “rest day" payments because of an ongoing staff shortage due to the training of new recruits being delayed by Covid restrictions.
The union will next week seek to extend the dispute further by balloting ScotRail engineers for industrial action too.
ScotRail said it would be able to operate some routes on Sundays with cover from managers and support staff who will stand in for ticket examiners.
It said it hoped to increase the number of trains running during subsequent Sunday strikes.
The operator is angry at the timing of the wider walkouts, which come as it starts the recovery from restrictions during the pandemic which limited travel to essential journeys.
This week, passenger numbers have increased from 10 per cent to around 30 per cent of normal.
Trains due to run on Sunday:
Glasgow – Ayr: 0900 and every hour until 1900
Ayr – Glasgow: 0845 and every hour until 1945
Stops in both directions: Paisley Gilmour St, Johnstone, Kilwinning, Irvine, Barassie, Troon, Prestwick International, Prestwick Town, Newton on Ayr.
Glasgow – Largs: 0940 and every hour until 1940
Largs – Glasgow: 0954 and every hour until 1954
Stops in both directions: Paisley Gilmour St, Johnstone, Milliken Park, Howwood, Lochwinnoch, Glengarnock, Dalry, Kilwinning, Stevenston, Saltcoats, Ardrossan South Beach, West Kilbride, Fairlie.
Glasgow – Wemyss Bay: 0850 and every hour until 1850
Wemyss Bay – Glasgow: 0850, 0950, 1055, 1150, 1250, 1350, 1450, 1555, 1650, 1750, 1855
Stops in both directions: Hillington East, Paisley Gilmour St, Bishopton, Port Glasgow, Whinhill, Drumfrochar, Branchton, Inverkip.
Glasgow – Gourock: 0920 and hourly until 1820 then 1921
Gourock – Glasgow: 0923 and hourly until 1923
Stops in both directions: Cardonald, Hillington East, Hillington West, Paisley Gilmour St, Paisley St James, Bishopton, Langbank, Woodhall, Port Glasgow, Bogston, Cartsdyke, Greenock Central, Greenock West, Fort Matilda.
Helensburgh – Airdrie: 0855, 0955, 1054, 1155, 1255, 1354, 1455, 1555, 1655, 1755, 1855
Airdrie – Helensburgh: 0930, 1031, 1128, 1228, 1328, 1430, 1529, 1628, 1728, 1828, 1928
Stops in both directions: Craigendoran, Cardross, Dalreoch, Dumbarton Central, Dumbarton East, Dalmuir, Singer, Drumry, Drumchapel, Westerton, Annieland, Hyndland, Partick, Charing Cross, Glasgow Queen St, High Street, Bellgrove, Carntyne, Shettleston, Garrowhill, Easterhouse, Blairhill, Coatbridge Sunnyside, Coatdyke.
Balloch – Airdrie: 0929, 1029, 1128, 1227, 1328, 1428, 1528, 1628, 1728, 1827, 1928
Airdrie – Balloch: 0857, 0959, 1058, 1157, 1258, 1358, 1458, 1559, 1659, 1758, 1859
Stops in both directions: Alexandria, Renton, Dalreoch, Dumbarton Central, Dumbarton East, Bowling, Kilpatrick, Dalmuir, Clydebank, Yoker, Garscadden, Scotstounhill, Jordanhill, Hyndland, Partick, Charing Cross, Glasgow Queen St, High Street, Bellgrove, Carntyne, Shettleston, Garrowhill, Easterhouse, Blairhill, Coatbridge Sunnyside, Coatdyke.
ScotRail head of customer operations Phil Campbell said: “The RMT’s strike action is wrong and will have a significant impact on customers who are returning to the railway as lockdown eases.
"At a time when we need to attract people back to the railway to recover the business and secure jobs, the RMT’s damaging actions will turn people away.
“Industrial action will have no impact on ScotRail’s position on 50 per cent overtime pay increases for no additional hours worked, given the severe financial challenges we face."
RMT general secretary Mick Cash said: “It is frankly appalling that once again [ScotRail operator] Abellio have resorted to launching attacks on their hard-working staff on social media this week rather than agreeing to talks aimed at resolving this long-running dispute over pay equality across ScotRail grades.
“There has also been a deafening silence from the political leadership in Scotland who are more interested in electoral photo opportunities than they are in putting pressure on Transport Scotland and the ScotRail operators to play fair by their staff out there on the front line throughout the Covid pandemic.
“We now have the appalling prospect of poorly-trained managers being drafted in without any experience to scab on RMT members jobs, regardless of the safety consequences.
“If Abellio and Transport Scotland think our members are going to be burnt off by this refusal to engage then they know nothing of their own workforce and their resilience.
"RMT remains available for talks and it’s about time the company started acting responsibly and took up that offer.”
Over the last five Sundays, only trains in the Glasgow area have operated during the walkouts by conductors.
However, the addition of ticket examiners to the strikes will halt most services in and around Scotland’s largest city, where around two in three of ScotRail’s passengers normally travel.
Passenger numbers slumped to just 10 per cent of normal during the most recent lockdown, but have since recovered to around 30 per cent on some days this week.