Powertrain Controls - ECM/PCM

DTC 49 "Service Engine Soon" Lamp Circuit Fault:

Service Throttle Soon Lamp Circuit Fault:

CIRCUIT DESCRIPTION
There should be a "Service Throttle Soon" lamp when the ignition is "ON" and the engine "OFF" for 2 seconds. The Powertrain Control Module (PCM) will control the "Service Throttle Soon" and turn it "ON" by providing a ground path.

DIAGNOSTIC TROUBLE CODE (DTC) 49 WILL SET WHEN
Ignition voltage on CKT 960 when PCM is requesting "Service Throttle Soon" lamp "ON."
OR
No ignition voltage on terminal "PA5" when PCM is requesting "Service Throttle Soon" lamp "OFF."

ACTION TAKEN (PCM will default to)
DTC 49 will not turn "ON" the Malfunction Indicator Lamp (MIL), but will set a current and history DTC.

DTC 49 WILL CLEAR WHEN
The fault condition(s) no longer exist.

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This test checks the ability of the PCM to command the STS lamp.
2. This test will determine if there is an open in ignition feed circuit or CKT 970.

DIAGNOSTIC AIDS
Check for faulty bulb or fuse. An open in CKT 960 will cause a DTC 49 to set.