Test Procedure

If you were not directed here from Lighting chart A-1, then a wrong diagnosis could result. See 1989 SELF-DIAGNOSTICS -- ALLANTE article in ENGINE PERFORMANCE.
If code B441 is also set, then a loss of voltage on circuit No. 840 is the cause of the fault.
Checks for voltage on circuit No. 840. Circuit No. 840 is the voltage supply circuit for the LSP.
Checks the data line for proper connection to the LSP.

Fig 1: DTC L110: Left Switch Pod (LSP) Communication Failure Flow Chart

Courtesy of GENERAL MOTORS CORP.

Fig 2: DTC L110: Left Switch Pod (LSP) Communication Failure Flow Chart Circuit

Courtesy of GENERAL MOTORS CORP.