GM Service Manual Online
For 1990-2009 cars only

Object Number: 1570853  Size: SF
Automatic Transmission Controls Schematics

Circuit Description

The engine control module (ECM) determines when the vehicle is in Park "P" or Neutral "N" gear position through the transmission range switch. The BLK/RED wire to the ECM is grounded by the transmission range switch when the transmission manual selector is in either Park "P" or Neutral "N" gear position.

DTC Detecting Condition

    • Engine speed changed from below 300 rpm to over 500 rpm when vehicle speed is 0 km/h (0 mph) and the transmission range switch is "open" (R, D, 2 or L gear positions).
    • Transmission range switch "closed" (P or N gear position) is detected for 10 seconds while engine is running at over 2,000 rpm and with more than 48.6% calculated load value.

Action Taken When the DTC Sets

    • DTC P1715 is stored.
    • The OD/OFF indicator turns ON.
    • The malfunction indicator lamp (MIL) turns ON.

Diagnostic Aids

An intermittent condition may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation. Inspect the ECM and TCM harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals and for poor terminal-to-wire connections.

Test Description

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

  1. Checks for operation of the transmission range switch.

  2. Checks for an open in the BLK/RED wire.

  3. Checks that the transmission range switch opens when the manual selector is not in either Park or Neutral gear positions.

  4. Determines whether the transmission range switch stays closed at all times or BLK/RED wire is shorted to ground.

  5. Checks for an open in the BLK/RED wire.

Step

Action

Value(s)

Yes

No

1

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

--

Go to Step 2

Go to On-Board Diagnostic System Check

2

  1. Place the transmission manual selector to the PARK "P" position.
  2. Step firmly on the brake pedal.
  3. Turn the ignition switch to START.

Does the engine crank?

--

Go to Step 3

Perform System Diagnosis Starter System in Engine Electrical

3

  1. Turn the ignition switch to LOCK.
  2. Connect the DVM between ground the ECM connector C2 terminal 22 by backprobing.
  3. Turn the ignition switch to ON.
  4. Measure the voltage.

Is the voltage at or less than the value specified?

1 V

Go to Step 4

Go to Step 11

4

  1. Set the parking brake and step firmly on the brake pedal.
  2. Shift the transmission manual selector to REVERSE "R", DRIVE "D", SECOND "2" and LOW "L" positions while monitoring the voltage on the DVM.

Is the voltage within the specified values on each of the gear positions mentioned above?

10-14 V

Go to Step 9

Go to Step 5

5

  1. Turn the ignition switch to the LOCK position.
  2. Disconnect the transmission range switch.
  3. Turn the ignition switch to ON.
  4. With the DVM still connected to the ECM connector C2 terminal 22, measure the voltage.

Is the voltage within the specified values?

10-14 V

Go to Step 7

Go to Step 6

6

  1. Turn the ignition switch to LOCK position.
  2. Disconnect the ECM connector C2.
  3. Connect the DVM between ground and the ECM connector C2 terminal 22.
  4. Measure the resistance.

Is the resistance within the specified value?

Go to Step 7

Go to Step 12

7

  1. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  2. Shift the transmission manual selector the NEUTRAL "N" position.
  3. Loosen the transmission range switch manual selector shaft nut.
  4. Loosen the transmission range switch bolt.
  5. Pivot the transmission range switch as far clockwise (downward) as possible.
  6. Slowly pivot the transmission range switch counterclockwise until the DVM displays continuity.

Can continuity be obtained?

--

Go to Step 8

Go to Step 13

8

  1. Tighten the PNP switch bolts to 21 N·m (15 lb ft).
  2. Tighten the manual selector nut to 19 N·m (14 lb ft).
  3. Reconnect all connectors.

Is the action complete?

--

Go to Step 9

--

9

  1. Remove the ECM. Refer to Engine Control Module (ECM) Replacement in Engine Controls.
  2. Install a known, good ECM.
  3. Perform the DTC Confirmation Procedure.

Does this DTC reset?

--

Go to Step 10

Go to Step 14

10

Inspect the BLK/RED wire and connectors between the ECM and the transmission range switch for damage which may result in an open circuit or short to ground with all the connectors connected. Repair damage, if evident.

Is the action complete?

--

Go to Step 15

--

11

Repair the open or high resistance in the BLK/RED wire between S224 and the ECM connector C2 terminal 22.

Is the action complete?

--

Go to Step 15

--

12

Repair the short to ground in the BLK/RED wire between the ECM connector C2 terminal 22 and the transmission range switch conductor terminal 2.

Is the action complete?

--

Go to Step 15

--

13

Replace the transmission range switch. Refer to Transmission Range Switch Replacement .

Does the DTC reset?

--

Go to Step 15

--

14

Replace the ECM. Refer to Engine Control Module Replacement in Engine Controls.

Is the action complete?

--

Go to Step 15

--

15

  1. Reconnect the connectors.
  2. Perform the DTC Confirmation Procedure.

Does the scan tool display any DTCs?

--

Go to the applicable DTC table

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