Diagnostic System Check

Ensure battery condition, cold cranking amperage and reserve capacity meet specifications. Replace as necessary. Install scan tool. If scan tool powers up, go to next step. If scan tool does not power up, see BODY CONTROL MODULES -- CATERA article.
Turn ignition on, engine off. Try to establish scan tool communication with Powertrain Control Module (PCM). If communication with PCM is established, go to next step. If communication with PCM is not established, see BODY CONTROL MODULES -- CATERA article.
Select display DTC function for ECM. Record all displayed DTCs and status of displayed DTCs. If DTCs are displayed, go to next step. If no DTCs are displayed, see SYMPTOM TESTS in this article, or TROUBLE SHOOTING - NO CODES article in ENGINE PERFORMANCE for diagnosis of other possible symptoms or intermittent condition.
Retrieve codes and perform appropriate test. See DIAGNOSTIC TROUBLE CODE INDEX table.

DIAGNOSTIC TROUBLE CODE INDEX

DTC ⁽¹⁾

Description

Cruise Control Brake Switch Circuit

P0603

⁽²⁾ ECM Long Term Memory Reset

Cruise Lamp Control Circuit

⁽¹⁾	For any DTC beginning with the letter "U", see BODY CONTROL MODULES -- CATERA article.

⁽²⁾	See SELF-DIAGNOSTICS -- GASOLINE -- 3.0L "V" BODY article in ENGINE PERFORMANCE for diagnosing this code.