DTC 99

DTC 99 Accelerator Pedal Position (APP) 5 Volt Reference Fault:

Accelerator Pedal Position (APP) 2-5 Volt Reference Fault:

CIRCUIT DESCRIPTION
The Accelerator Pedal Position (APP) module provides a voltage signal that changes relative to accelerator pedal position. There are three sensors located within the APP module that are scaled differently.

DIAGNOSTIC TROUBLE CODE (DTC) 99 WILL SET WHEN
Reference voltage on APP 2 below 4.8 volts for 2 seconds.

ACTION TAKEN (Powertrain Control Module (PCM) will default to)
If DTC 99 is present, the PCM will turn "ON" the "Service Throttle Soon" lamp and limit power.

DTC 99 WILL CLEAR WHEN
The fault condition(s) no longer exist, and the ignition switch is cycled "OFF" then "ON."

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This step will determine if there is a good 5 volt reference.

DIAGNOSTIC AIDS
A Tech 1 scan tool reads APP 2 position in volts. It should read about 4.5 volts with throttle closed and ignition "ON" or at idle. Voltage should decrease at a steady rate as throttle is moved toward Wide Open Throttle (WOT).
A short to ground in CKT 996 will result in a DTC 99.
Refer to Intermittents. - Intermittent Malfunctions
Scan APP signal while depressing accelerator pedal with engine stopped and ignition "ON." Display should vary from about 4.5 volts when throttle was closed, to about 1.5 volts when throttle is held at Wide Open Throttle (WOT) position.