GM Service Manual Online
For 1990-2009 cars only

TFP Valve Position Switch Resistance Check

Step

Action

Value(s)

Yes

No

Important: Whenever the transmission 20-way connector is disconnected, and the engine is running, multiple DTCs set. Clear any codes after finishing the procedure.

1

  1. Install the J 39775 jumper harness on the transmission side of the 20-way connector.
  2. Using the J 39200 digital multimeter (DMM) and the J 35616 connector test adapter kit, measure the resistance from terminal N to the transmission case.

Is the resistance greater than the value indicated?

50 kohms

Go to Step 3

Go to Step 2

2

  1. Disconnect the automatic transmission (A/T) wiring harness assembly from the TFP manual valve position switch.
  2. Measure the resistance from terminal A of the TFP manual valve position switch to the switch housing.

Is the resistance greater than the value indicated?

50 kohms

Go to Step 15

Go to Step 16

3

Measure the resistance from terminal R to the transmission case.

Is the resistance greater than the indicated value?

50 kohms

Go to Step 5

Go to Step 4

4

  1. Disconnect the A/T wiring harness assembly from the TFP manual valve position switch.
  2. Measure the resistance from terminal B of the TFP manual valve position switch to the switch housing.

Is the resistance greater than the value indicated?

50 kohms

Go to Step 15

Go to Step 16

5

Measure the resistance from terminal P to the transmission case.

Is the resistance greater than the value indicated?

50 kohms

Go to Step 7

Go to Step 6

6

  1. Disconnect the A/T wiring harness assembly from the TFP manual valve position switch.
  2. Measure the resistance from terminal C of the TFP manual valve position switch to the switch housing.

Is the resistance greater than the value indicated?

50 kohms

Go to Step 15

Go to Step 16

7

  1. Start the engine and let the engine idle.
  2. Set the parking brake.
  3. Place the gear selector in DRIVE (D4).
  4. Measure the resistance from terminal R to the transmission case.

Is the resistance less than the indicated value?

200ohms

Go to Step 8

Go to Step 14

8

  1. Place the gear selector in DRIVE (D4).
  2. Measure the resistance from terminal P to the transmission case.

Is the resistance less than the value indicated?

200ohms

Go to Step 9

Go to Step 14

9

  1. Place the selector in LOW (D1).
  2. Measure the resistance from terminal N to the transmission case.

Is the resistance less than the value indicated?

200ohms

Go to Step 10

Go to Step 14

10

  1. Place the gear selector in LOW (D1).
  2. Measure the resistance from terminal P to the transmission case.

Is the resistance greater than the value indicated?

50 kohms

Go to Step 11

Go to Step 16

11

  1. Place the gear selector in REVERSE (R).
  2. Measure the resistance from terminal N to the transmission case.

Is the resistance less than the value indicated?

200ohms

Go to Step 12

Go to Step 16

12

  1. Place the transmission in REVERSE (R).
  2. Measure the resistance from terminal P to the transmission case.

Is the resistance greater than the value indicated?

50 kohms

Go to Step 13

Go to Step 16

13

  1. Place the gear selector in Manual THIRD (D3).
  2. Measure the resistance from terminal R to the transmission case.

Is the resistance greater than the value indicated?

50 kohms

System OK

Go to Step 16

14

  1. Disconnect the A/T wiring harness from the TFP manual valve position switch.
  2. Inspect CKT 1224 (PNK), 1225 (DK BLU), and 1226 (RED) of the A/T wiring harness assembly for an open circuit.

Was a condition found?

--

Go to Step 15

Go to Step 16

15

Replace the A/T wiring harness assembly.

Refer to Wiring Harness Replacement.

Is the replacement complete?

--

Go to Step 1

--

16

  1. Replace the TFP manual valve position switch.
  2. Refer to Control Valve Body Replacement .

  3. Inspect the A/T wiring harness assembly.

Is the replacement of the TFP manual valve position switch complete?

--

Go to Step 1

--