GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Blazer - 4WD 🢒 Restraints 🢒 SIR 🢒 DTC 001

Circuit Description

The transfer case shift control module (TCCM) normally has battery voltage supplied through the battery positive voltage circuit at all times. When the ignition is ON, the TCCM conducts a self-test. This self-test determines if the current memory is the same memory that was retained when the ignition was last turned OFF. This self-test indicates whether the random access memory (RAM) standby power-supply to the TCCM pin C6 was interrupted. If the power is interrupted, the diagnostic trouble codes (DTCs) would be cleared from memory. If the self-test fails, the TCCM sets DTC 001.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC 001 RAM Standby Power Supply Failure

Conditions for Clearing the DTC

This DTC will clear when the voltage supply failure has been corrected and the ignition switch has been cycled 5 times.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step inspects the CTSY LP fuse for an open.

    2.

  2. This step tests the battery positive voltage circuit for an open or high resistance.

    3.

  3. This step rechecks the CTSY LP fuse for an open.

    4.

  4. This step tests the battery positive voltage circuit for a short to ground.

DTC 1 - RAM Standby Power Loss

Step

Action

Yes

No

Schematic Reference: Transfer Case Control Schematics

1

Important: Check the transfer case shift control module for DTCs. The transfer case shift control module is not a class 2 device. DTCs are displayed on the transfer case shift control switch. Use the following 4 steps to obtain DTCs.

  1. Turn OFF the ignition for 10 seconds.
  2. Connect PIN 13 on the data link cable (DLC) to a ground. The DLC is located in the cab under the instrument panel on the driver side.
  3. Turn ON the ignition, with the engine OFF.
  4. Observe the transfer case shift control switch select buttons for flashing codes.

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

Important: This code can get set falsely due to the improper clearing of DTCs or replacement of a blown CTSY LP fuse.

Inspect the CTSY LP fuse for an open.

Was there a problem found?

Go to Step 4

Go to Step 3

3

  1. Test the battery positive voltage circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
  2. Cycle the ignition 5 times. Check to see if DTC 001 has cleared.

Has DTC 001 cleared?

Go to Step 7

Go to Step 6

4

  1. Replace the fuse.
  2. Drive the vehicle under various road conditions and retest the fuse.

Did the fuse blow again?

Go to Step 5

Go to Step 7

5

Test the battery positive voltage circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 7

Go to Step 6

6

Replace the TCCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 7

--

7
  1. Clear all DTCs from memory. Refer to Diagnostic Trouble Code (DTC) Clearing .
  2. Operate the vehicle while pressing each of the buttons on the transfer case shift control switch.

Does the DTC reset?

Go to Step 2

System OK