GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P0698: 5-Volt Reference 3 Circuit Low Voltage

DTC P0699: 5-Volt Reference 3 Circuit High Voltage

Diagnostic Fault Information

Circuit

Short to Ground

High Resistance

Open

Short to Voltage

Signal Performance

APP Sensor 1 - 5-Volt Reference

P0698, P2122, P2564

P2138

P2122

P0699, P2123, P2227

--

MAP Sensor - 5-Volt Reference

P0698, P0107

P0101

P0107

P0699, P0106

--

TC Vane Position Sensor - 5-Volt Reference

P0698, P2564

P2563

P2564

P0699, P2565

--

EGR Valve - 5-Volt Reference

P0698

P046C

P0405

P0699, P0401

--

Circuit/System Description

These 5-volt reference circuits are independent of each other outside the engine control module (ECM), but are bussed together inside the ECM. Therefore, a circuit condition on one sensor 5-volt reference circuit may affect the other sensor 5-volt reference circuits. The ECM monitors the voltage on the 5-volt reference circuit.

Conditions for Running the DTC

    • The ignition is ON.
    • Diagnostics run continuously.

Conditions for Setting the DTC

P0698

    • The ECM detects the 5-volt reference 3 circuit voltage is less than 4.7 volts.
    • The above condition is present for 2 seconds.

P0699

    • The ECM detects the 5-volt reference 3 circuit voltage is more than 5.2 volts.
    • The above condition is present for 2 seconds.

Action Taken When the DTC Sets

    • The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
    • The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

Conditions for Clearing the MIL/DTC

    • The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
    • A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
    • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
    • Clear the MIL and the DTC with a scan tool.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

    •  Engine Control Module Connector End Views
    •  Engine Controls Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Circuit/System Verification

  1. Engine Starts and runs.
  2. Engine running, observe the DTC information with a scan tool. DTCs P0698 or P0699 should not set.
  3. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

  1. Turn OFF the ignition for 30 seconds or until the ECM powers down.
  2. Disconnect the accelerator pedal position (APP) sensor.
  3. Turn ON the ignition, with engine OFF and measure the voltage from the 5-volt reference circuit of the APP sensor 1 to a good ground with a DMM.
  4. If the voltage measures 4.7-5.2 volts, replace the APP sensor .
  5. With the DMM still connected to the 5-volt reference circuit, disconnect all other components connected to the 5-volt reference 3, one at a time.
  6. If voltage changes when one of the above components are disconnected, replace the component. Refer to the appropriate replacement procedure.
  7. Test the 5-volt reference 3 circuits for a short to ground or a short to voltage.
  8. If no problem was found in the 5-volt reference 3 circuit , replace the ECM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Accelerator Pedal Position Sensor Replacement
    •  Manifold Absolute Pressure Sensor Replacement
    •  Turbocharger Vane Position Sensor Replacement
    •  Exhaust Gas Recirculation Valve Replacement
    •  Control Module References for ECM replacement, setup, and programming