December 2000 Issue
Issue Summary:
Most of the vehicles we are working on have computer-controlled transmissions, so we will be bringing you the latest types of checks to help in diagnosing the vehicles’ transmission problems.
The 4L60-E and 4L80-E transmissions used in General Motors C/K trucks can be stuck in fail-safe. One of the causes could be a blown fuse but the replacement fuse also blows. We have a check procedure and the common cause for that problem.
Sometimes scan tools can give incorrect information on GM THM 4T80-E units with diagnostic trouble code P056 stored. You should access the codes through the onboard diagnostic system on Cadillacs.
Mazdas equipped with the R4A-EL transmission may exhibit normal 1-2 and 2-3 upshifts but no 4th gear. The cause could be a faulty or misadjusted inhibitor switch, a faulty theft-deterrent system or a grounded wire harness leading to the inhibitor-signal fuse.
Nissan Maximas equipped with the RE4FO2A may have only a 1-2 shift and the reverse lamps do not illuminate. The cause may be that the connector for the auxiliary air-control valve has been switched with the inhibitor-switch connector.
