Chevrolet Silverado / GMC Sierra. Service manual — part 1010

RANGE SELECTOR DISPLAYS INCORRECT RANGE

Torque converter diagnosis

TCC does not apply

TCC does not release

TCC apply/release quality

Apply (300 RPM Slip).

Refer to No Torque Converter Clutch
Release.

Refer to Torque Converter Clutch
Shudder.

Indicator On or Message Center Displays
Message:
This category contains the following topics:
Message Center displays "change trans fluid"

Refer to Transmission Component and
System Description.

If symptom is not found

Refer to Transmission Fluid Check.

Refer to Road Test.

Refer to Line Pressure Check.

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E/4L70-E - Cab & Chassis Sierra, Cab & Chassis

Silverado, Sierra & Silverado

Fig. 1: Range Selector Schematic
Courtesy of GENERAL MOTORS CORP.

CIRCUIT DESCRIPTION

The transmission range (TR) switch is part of the park/neutral position (PNP) and back-up lamp
switch assembly, which is externally mounted on the transmission manual shaft. The TR switch
contains four internal switches that indicate the transmission gear range selector lever position.
The transmission control module (TCM) supplies ignition voltage to each switch circuit. As the
gear range selector lever is moved, the state of each switch may change, causing the circuit to
open or close. An open circuit or switch indicates a high voltage signal. A closed circuit or switch
indicates a low voltage signal. The TCM detects the selected gear range by deciphering the
combination of the voltage signals. The TCM compares the actual voltage combination of the
switch signals to a TR switch combination chart stored in memory.

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E/4L70-E - Cab & Chassis Sierra, Cab & Chassis

Silverado, Sierra & Silverado

DIAGNOSTIC AIDS

Refer to Transmission Range Switch Logic table for valid combinations of switch signal
circuits A, B, C and Parity. On the table, HI indicates an ignition voltage signal. LOW indicates a
zero voltage signal.

TEST DESCRIPTION

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

4: By disconnecting the TR switch, the ground path of all TR switch circuits is removed and
the TCM should recognize all circuits as open. The scan tool should display HI for all range
signal states.

5: This step tests the TR switch wiring for an open or the lack of the signal voltage from the
TCM.

6: This step tests the TR switch wiring and the TCM by providing a ground path through a
fused jumper wire. When grounded, the scan tool range signal states should change to LOW.

7: This step tests the TR switch wiring and the TCM by providing a ground path through a
fused jumper wire. When grounded, the scan tool range signal states should change to LOW.

8: This step tests the TR switch wiring and the TCM by providing a ground path through a
fused jumper wire. When grounded, the scan tool range signal states should change to LOW.

9: This step tests the TR switch wiring and the TCM by providing a ground path through a
fused jumper wire. When grounded, the scan tool range signal states should change to LOW.

Range Selector Displays Incorrect Range

Step

Action

Values

Yes

No

1

1. Install a scan tool.

2. Turn ON the ignition, with the

engine OFF.

3. Select TR Sw. on the scan tool.

4. With the scan tool, observe the TR

Sw. display while selecting each
transmission range: P, R, N, D4, D3,
D2 and D1.

Does each selected transmission range
match the scan tool TR Sw. display?

-

Go to Step 2 Go to Step 3

Go to Testing

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E/4L70-E - Cab & Chassis Sierra, Cab & Chassis

Silverado, Sierra & Silverado

2

Observe the IPC gear range display while
selecting each transmission range: P, R, N,
D4, D3, D2, D1.
Does each selected transmission range
match the IPC display?

-

for
Intermittent
Conditions
and Poor
Connections

Go to Step

16

3

With the scan tool, observe the TR Sw.
A/B/C/P display.
Does the scan tool TR Sw. A/B/C/P
parameter indicate HI for all range signal
states?

-

Go to Step 13 Go to Step 4

4

1. Turn OFF the ignition.

2. Disconnect the TR switch 4-way

connector.

3. Turn ON the ignition, with the

engine OFF.

Does the scan tool TR Sw. A/B/C/P
parameter indicate HI for all range signal
states?

-

Go to Step 5

Go to Step

10

5

1. Using the DMM and the J 35616

GM Terminal Test Kit, measure the
voltage from the transmission range
signal A circuit of the TR switch
connector to ground.

2. Measure the voltage from the

transmission range signal B circuit of
the TR switch connector to ground.

3. Measure the voltage from the

transmission range signal C circuit of
the TR switch connector to ground.

4. Measure the voltage from the

transmission range signal P circuit of
the TR switch connector to ground.

Does the voltage measure within the
specified range at all 4 circuits?

10-12 V

Go to Step 6

Go to Step

11

Connect a fused jumper wire from the TR
switch connector, signal circuit A, to

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E/4L70-E - Cab & Chassis Sierra, Cab & Chassis

Silverado, Sierra & Silverado