For the second time in four days, General Motors has issued a major recall. This time, it's for 636,000 mid-sized SUVs. Most are in the United States, but 31,000 are in Canada.

The recall is to fix a problem with the windshield wiper module. Under certain conditions, electronics could short-circuit when water leaks into the module. GM has received two reports of crashes related to the problem. Neither crash involved injuries.

GM will begin notifying vehicle owners beginning in the third quarter of this year. The company says the reason for the delay is the automaker has to test the materials and the adhesives used to fix the problem.

Models involved are year 2002 and 2003 Chevrolet TrailBlazer and TrailBlazer EXT, GMC Envoy and Envoy XL, and Oldsmobile Bravada SUV models as well as some Isuzu Motors Ltd. Ascenders.

Last Friday, GM recalled 1.8 million cars to fix an electrical defect that could cause fires in the steering column. GM said it had received 80 reports of problems. None involved injuries. About 337,000 of the cars were sold in Canada.

The models involved include 1998-2001 Chevrolet Cavaliers and Pontiac Sunfires and 1998 Pontiac Grand Ams, Oldsmobile Achievas and Buick Skylarks.