GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1999 🢒 Chevy C Silverado - 2WD 🢒 DTC 🢒 DTC B3148 RF Unlock Switch Circuit High

For a full page schematic, refer to

Cell 51: Uplevel Door Locks


Object Number: 366607 Size: FS
Body Control Module Components
Body Control System Circuit Description
Cell 51: Base Power Door Locks
Cell 51: Passlock Sensor, VSS Signal
Handling ESD Sensitive Parts Notice
Power Distribution Schematics
Power Distribution Schematics
Door Lock/Indicator Schematics
Ground Distribution Schematics
Door Lock/Indicator Schematics
 in Body Control Module Schematics.

Circuit Description

The body control module (BCM) monitors and supplies an output voltage on circuit 194 to UNLOCK the doors. When the BCM receives a UNLOCK signal from the remote control door lock receiver to UNLOCK the passenger door the BCM supplies voltage to the UNLOCK relay and UNLOCKS the door.

Conditions for Setting the DTC
    • When circuit 194 is shorted to battery voltage for approximately 3 minutes.
    • The system voltage must be between 9.0 volts and 16.0 volts.

Action Taken When the DTC Sets

The power door UNLOCK system will not function with the remote control door lock receiver system or either door switches.

Conditions for Clearing the MIL/DTC
    • A current DTC will clear immediately after the short to battery voltage is corrected.
    • A history DTC will clear after 100 consecutive ignition cycles without a fault present.
    • History and current DTC(s) can be cleared using a scan tool.

Diagnostic Aids
    • Always diagnose the first DTC listed on the scan tool.
    • The scan tool must display DTC B3148 as a current code before performing diagnostics.
    • Perform a visual check for loose or poor connections at all related components
    • Refer to Intermittents and Poor Connections in Wiring Systems.

Test Description

Step number(s) below refer to the same step number(s) in the Diagnostic Table

  1. This step determines if the LH power door lock switch is shorted to battery voltage.

  1. This step determines if the RH power door lock switch is shorted to battery voltage.

  1. This step determines if the circuit 194 is shorted to battery voltage or the BCM is defective.

Step

Action

Value(s)

Yes

No

1

Was the BCM Diagnostic System Check performed?

--

Go to Step 2

Go to Diagnostic System Check - Body Control System

2

  1. With a scan tool monitor the current DTCs.
  2. Disconnect the LH power door lock switch.

Does the Scan tool display B3148 as a current code?

--

Go to Step 3

Go to Step 6

3

  1. With a scan tool monitor the current DTCs.
  2. Disconnect the RH power door lock switch.

Does the Scan tool display B3148 as a current code?

--

Go to Step 4

Go to Step 7

4

  1. Disconnect the brown BCM (C1) connector and remove the comb from the connector.
  2. Backprobe (to prevent damage to the terminal), with a DMM , measure the voltage between CKT 194 (WHT) wire cavity A3 and ground.

Does the DMM display battery voltage?

--

Go to Step 5

Go to Step 8

5

Locate and repair the short to battery voltage CKT 194 (WHT) wire between the BCM and the UNLOCK relay and or the RH and LH power door lock switches.

Is the repair complete?

--

Go to Step 9

--

6

Replace the LH power door lock switch.

Is the repair complete?

--

Go to Step 9

--

7

Replace the RH power door lock switch.

Is the repair complete?

--

Go to Step 9

--

8
  1. Replace the BCM. Refer to Body Control Module Replacement .
  2. Program the BCM with the proper calibrations. Refer to Body Control Module (BCM) Programming/RPO Configuration .
  3. Perform the learn procedure.

Is the repair complete?

--

System OK

--

9
  1. Re-connect all disconnected components.
  2. Clear the DTC(s).

Is the Action complete?

--

System OK

--