GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1996 🢒 GMC Suburban - 4WD 🢒 Engine 🢒 Engine Controls - 6.5L 🢒 DTC P1635 5 Volt Reference Circuit

Object Number: 29574 Size: LF
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice
Engine Controls Components
EGR Control Pressure/BARO, IAT, ECT, and Boost Pressure Sensors
OBD II Symbol Description Notice

Circuit Description

The PCM provides a 5 volt supply for use in powering up sensors. This test monitors the voltage present at terminals BRD13 (shared by Boost, EGR Control Pressure/Baro and Crankshaft Position sensors) and BRD14 (Optical/Fuel temperature sensor (Cam/HI.Res). This is a type D DTC.

Conditions for Setting the DTC

5 volt reference is less than 1 volt.

Action Taken When the DTC Sets
    • Backup fuel
    • No EGR.
    • No turbo boost.

Conditions for Clearing the MIL/DTC
    • A History DTC will clear when forty consecutive warm-up cycles that the diagnostic does not fail (coolant temperature has risen 5°C (40°F) from start up coolant temperature and engine coolant temperature exceeds 71°C (160°F) that same ignition cycle.
    • Use of a Scan tool

Diagnostic Aids

During the time the failure is present, the setting of additional DTCs that share a 5 volt reference may also set.

Test Description

Number(s) below refer to the Step number(s) on the Diagnostic Table.

  1. Checks to confirm that a DTC is still present.

    2.

  2. Checks to determine if there is a 5 volt reference from the PCM.

    3.

  3. Checks to determine if there is a short-to-ground in the reference circuit or a short-to-ground in the PCM.

Step

Action

Value(s)

Yes

No

1

Important: Before clearing DTCs use the scan tool Capture Info to record freeze frame and failure records for reference, as data will be lost when Clear Info function is used.

Was the On-Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2
  1. Scan Tool installed.
  2. Crank engine for 15 seconds or start up.

Does DTC reset?

--

Go to Step 3

Go to Step 5

3
  1. Ignition ON, engine OFF.
  2. Disconnect EGR Control Pressure/BARO sensor.
  3. With J 39200 DVM, probe 5 volt reference circuit at harness connector.

Is voltage less than the specified value?

4.0 V

Go to Step 4

Go to Step 6

4
  1. Disconnect PCM connector with EGR sensor 5 volt reference circuit.
  2. With test light connected to B+, probe 5 volt reference circuit at PCM harness.

Is test light ON?

--

Go to Step 7

Go to Step 8

5

DTC is intermittent. If no additional DTCs are stored, refer to Diagnostic Aids. If additional DTCs were stored refer to those table(s).

Are additional DTCs stored?

--

Go to the applicable DTC table

Go to Diagnostic Aids

6

Replace EGR Control Pressure/BARO sensor. Refer to Exhaust Gas Recirculation Control Pressure Sensor Replacement .

Is the action complete?

--

Go to Step 8

--

7

Repair short to ground in 5 volt reference circuit.

Is the action complete?

--

Go to Step 8

--

8

Replace the faulty PCM.

Important: If the PCM is faulty, the new PCM must be programmed.

Refer to Powertrain Control Module Replacement/Programming .

Is the action complete?

--

Go to Step 9

--

9
  1. Using the Scan Tool, select DTC, Clear Info.
  2. Start engine and idle at normal operating temperature.
  3. Select DTC, Specific, then enter the DTC number which was set.
  4. Operate vehicle within the conditions for setting this DTC as specified in the supporting text.

Does the Scan Tool indicate that this diagnostic Ran and Passed?

--

Go to Step 10

Go to Step 2

10

Using the Scan Tool, select Capture Info, Review Info.

Are any DTCs displayed that have not been diagnosed?

--

Go to the Applicable DTC table

System OK