GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2006 🢒 GMC Sierra Denali 🢒 Transmission/Transaxle 🢒 Automatic Transmission - Allison 🢒 Driver Shift Request Switch Circuit Diagnosis

Circuit Description

The driver shift request switch system allows the driver to manually shift gears by using the driver shift request switch located on the automatic transmission shift lever. Pushing the switch forward commands an upshift and pushing the switch rearward commands a downshift. The driver shift request switch is activated when the gear selector is in the manual (M) position.

Diagnostic Aids
    • Inspect the wiring for poor electrical connections at the transmission control module (TCM). Inspect for the following conditions:
       - A bent terminal
       - A backed out terminal
       - A damaged terminal
       - Poor terminal tension
       - A chafed wire
       - A broken wire inside the insulation
    • When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change.
    • You may have to drive the vehicle in order to experience a condition.

Test Description

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

  1. This step tests signal voltage to the TCM.

    2.

  2. This step tests supply voltage to the driver shift request switch.

    3.

  3. This step tests resistance of the driver shift request switch.

Step

Action

Value

Yes

No

Schematic Reference: Automatic Transmission Controls Schematics

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle

2
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Using the scan tool, measure ignition voltage.

Is the voltage within the specified value?

9-18 V

Go to Step 3

Go to DTC P0562 for low voltage or DTC P0563 for high voltage

3

  1. Turn OFF the ignition.
  2. Disconnect the 80-way connector at the TCM.
  3. Install the J 39700 100-pin breakout box, the J-47275 breakout box adapter, and the J 47275-1 magnetic overlay.
  4. Turn ON the ignition, with the engine OFF.
  5. Using a DMM, measure voltage at terminal 56 and a known good ground.
  6. Operate the driver shift request switch in the Tap Up and Tap Down position.

Is the voltage within the specified range?

0.5-2.5 V

Go to Diagnostic Aids

Go to Step 4

4

Using the J-35616 GM-approved terminal test kit, connect a DMM to terminal 21 and a known good ground of the driver shift request switch.

Is the voltage within the specified value?

B+

Go to Step 5

Go to Step 6

5

  1. Turn OFF the ignition.
  2. Disconnect the transmission shift lever harness connector.
  3. Using the J-35616 , connect a DMM to terminal 20 and 21 of the driver shift request switch.

Is the resistance within the specified value?

Normal State: 6.6-7.0 K Ω

Tap Up (+) Switch: 1.7-2.0 K Ω

Tap Down (-) Switch 3.7-4.2 K Ω

Go to Step 10

Go to Step 9

6

    Important: The condition that affects this circuit may exist in other connecting branches of the circuit. Refer to Power Distribution Schematics for complete circuit distribution.

  1. Inspect the ignition 0 voltage circuit for an open. Refer to Circuit Protection - Fuses.
  2. Replace the fuse if necessary.

Was the fuse open?

--

Go to Step 11

Go to Step 7

7

Test the ignition 0 voltage circuit of the automatic transmission driver shift request switch for an open between the fuse block and the automatic transmission driver shift request switch. Refer to Testing for Continuity and Wiring Repairs.

Did you find and correct the condition?

--

Go to Step 11

Go to Step 8

8

Test the signal circuit of the automatic transmission driver shift request switch for an open between the automatic transmission driver shift request switch and the TCM. Refer to Testing for Continuity and Wiring Repairs.

Did you find and correct the condition?

--

Go to Step 11

--

9

Replace the automatic transmission driver shift request switch. Refer to Shift Lever Replacement.

Did you complete the replacement?

--

Go to Step 11

--

10

Important: In most cases, the TCM is not at fault. Investigate thoroughly before replacing the TCM. Swap the TCM with a known good TCM prior to replacing.

Replace the TCM. Refer to Control Module References for replacement, setup and programming.

Did you complete the replacement?

--

Go to Step 11

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11

Operate the vehicle while using the driver shift request switch, in order to verify the repair.

Does the driver shift request switch function properly?

--

System OK

Go to Step 2