Decoder Module Test
- Locate decoder module under left side of instrument panel. Turn ignition switch to RUN position. Measure voltage between terminal "A" (White/Black wire) to ground. If battery voltage is present, go to next step. If not, check fuse No. 3, or repair open in White/Black wire.
- Measure voltage between terminal "A" (White/Black wire) and terminal "F" (Black/White wire). If battery voltage is present, go to next step. If not, repair open in Black/White wire.
- Using test light, check for voltage at terminal "B" only in D Overdrive, R and 2 position. Voltage should be present at terminal "C" only in D Overdrive, N and 1 position. Voltage should be present at terminal "D" only in P, 2 and 1 position. Voltage should be present at terminal "E" only in P, R and N position. See Fig 1
. If voltage is present where it should not be, check wire. If wire is okay, replace transaxle position switch.
Courtesy of GENERAL MOTORS CORP.
- If checks are correct, temporarily replace decoder module with a known good unit. If all circuits and displays work, permanently replace decoder module. If all circuits still do not function properly, reinstall original decoder module and replace instrument cluster.