Decoder Module

Locate Decoder module under left side of instrument panel. Place ignition switch in "RUN" position. Measure voltage between terminal "A" (White/Black wire) to ground. If battery voltage is present, go to step 2). 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 step 3) If not, repair open in Black/White wire.

Probe decoder module terminals and measure resistance to ground. See DECODER MODULE RESISTANCE table. Place gear selector switch in position indicated. See Fig 1 .

DECODER MODULE RESISTANCE

Terminal (Wire Color)

Resistance

Gear Position

C (Black/White)

0 ohms ⁽¹⁾

P, R, D, 2

C (Black/White)

infinite ohms ⁽²⁾

N/A

N, (D), 1D (Yellow)

0 ohms ⁽³⁾

R, N, (D), D

D (Yellow)

infinite ohms ⁽²⁾

P, 2, 1

E (Gray)

0 ohms ⁽³⁾

(D), D, 2, 1

E (Gray)

infinite ohms ⁽²⁾

P, R, N,

B (White)

0 ohms ⁽³⁾

P, N, D, 1

B (White)

infinite ohms ⁽²⁾

R, (D), 2,

⁽¹⁾	If measurement is incorrect, go to step 5).

⁽²⁾	If measurement is incorrect, replace transaxle position switch.

⁽³⁾	If measurement is incorrect, go to step 6).

If resistance readings are correct, check Light Green/Black and Dark Blue/White wires for an open. If wires are okay, go to step 7).
Check for open in both Black/White wires. If wires are okay, replace transaxle position switch.
Check for an open in associated wire between the transaxle position switch and the decoder module. If wire is okay, replace instrument cluster.
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.

Fig 1: LeSabre Decoder Module Connector

Courtesy of GENERAL MOTORS CORP.