Bulletin #234 Transmission Type: CD4E Date: 9-98 Topic: Trouble Code 628 A common complaint on CD4E’s is Trouble Code 628 ( Excessive TCC Slip Detected). When this codes is set the O/D Off indicator light may blink, and firmer than normal shifts may occur due to elevated line pressure. While there can be many causes for this code to set, one of the most common has been a piece of pump gasket blown out. There is an updated pump assembly available which has been redesigned to reduce the possibilty of gasket blow out. However, the real cause of gasket blow out may be due to accidental high pressure from pressure control system malfunctions and not design problems in the pump. See ATC Bulletin # 235 for information on preventing extreme high pressure problems/ failures. A blown out pump gasket may cause a code 628. In some cases this code may be intermitent, or only occur when very hot. Copyright© 1998/Paul Yaklin/ATC