GM Service Manual Online
For 1990-2009 cars only

Fuel Gauge Appears Inaccurate or Inoperative P72

P72 Fuel Gauge Appears Inaccurate or Inoperative

Step

Action

Value(s)

Yes

No

1

Does the fuel gauge read accurately?

--

System OK

Go to Step 2

2

Does the fuel gauge indicate empty when there is fuel in the tank?

--

Go to Step 15

Go to Step 3

3

Does the fuel gauge indicate full (or beyond full) at all times?

--

Go to Step 10

Go to Step 4

4

  1. Disconnect the fuel pump connector.
  2. Connect one red lead of the J 39200 to the PPL (30) wire.
  3. Connect the other lead to the ground.
  4. Set the resistance dials to 0 ohms and then to 900 ohms.

Does the fuel gauge indicate empty and full? (Allow time for the gauge to reach full, due to the antislosh device.)

0 ohms (empty)

900 ohms (full)

Go to Step 5

Go to Step 7

5

Check the BLK (150) wire for high resistance.

Is the resistance at the specified value?

Greater than 90 ohms

Go to Step 6

Go to Step 16

6

Replace the fuel pump.

Is the repair complete?

--

Go to Step 1

--

7

Does the fuel gauge indicate empty?

--

Go to Step 8

Go to Step 3

8

Check for high resistance in the PPL (30) wire.

Is the resistance at the specified value?

Greater than 90 ohms

Go to Step 9

Go to Step 16

9

Replace the fuel gauge.

Is the repair complete?

--

Go to Step 1

--

10

  1. Disconnect the fuel pump and the sender connector.
  2. Place the ignition switch in RUN.
  3. Connect a fused jumper from the PPL (30) wire at the fuel pump and the sender connector to the ground.

Does the fuel gauge indicate empty?

--

Go to Step 11

Go to Step 13

11

Connect a fused jumper from the PPL (30) wire to the BLK (150) wire at the fuel pump and the sender connector.

Does the fuel gauge indicate empty?

--

Go to Step 12

Go to Step 14

12

Replace the fuel pump.

Is the repair complete?

--

Go to Step 1

--

13

Locate an open in the PPL (30) wire between the fuel pump, the sender connector and the fuel gauge.

Is the PPL (30) wire open?

--

Go to Step 16

Go to Step 9

14

Locate an open in the BLK (150) wire between the fuel pump, the sender connector and ground G400.

Is the BLK (150) wire open?

--

Go to Step 16

--

15

  1. Disconnect the fuel pump.
  2. Place the ignition switch in RUN.

Does the fuel gauge indicate full?

--

Go to Step 6

Go to Step 13

16

Repair or replace the wire.

Is the repair complete?

--

Go to Step 1

--

Fuel Gauge Appears Inaccurate or Inoperative P92

P92 Fuel Gauge Appears Inaccurate or Inoperative

Step

Action

Value(s)

Yes

No

1

Does the fuel gauge read accurately?

--

System OK

Go to Step 2

2

Does the fuel gauge indicate empty when there is fuel in the tank?

--

Go to Step 14

Go to Step 3

3

Does the fuel gauge indicate full (or beyond full) at all times?

--

Go to Step 10

Go to Step 4

4

  1. Disconnect the fuel pump connector.
  2. Connect the one red lead of J 39200 to W
  3. Connect the lead to the ground.
  4. Set the resistance dials.

Does the fuel gauge indicate empty and full? (Allow time for gauge to reach full due to antislosh device.)

0 ohms (empty)

90 ohms (full)

Go to Step 5

Go to Step 7

5

Check the WHT (14) wire for high resistance.

Is the resistance at the specified value?

>90 ohms

Go to Step 6

Go to Step 15

6

Replace the fuel pump.

Is the repair complete?

--

Go to Step 11

--

7

Does the fuel gauge indicate empty?

--

Go to Step 8

Go to Step 3

8

Check for high resistance in the WHR (16) wire.

Is the resistance at the specified value?

>90 ohms

Go to Step 9

Go to Step 15

9

Replace the fuel gauge.

Is the repair complete?

--

Go to Step 1

--

10

  1. Disconnect the fuel pump and the sender connector.
  2. Place the ignition switch in RUN.
  3. Connect a fused jumper from the WHR (16) wire at the fuel pump and the sender connector to ground.

Does the fuel gauge indicate empty?

--

Go to Step 11

Go to Step 12

11

Connect a fused jumper from the WHR (16) wire to the WHT (14) wire at the fuel pump and the sender connector.

Does the fuel gauge indicate empty?

--

Go to Step 6

Go to Step 13

12

Locate an open in the WHR (16) wire between the fuel pump, the sender connector, and the fuel gauge.

Is the WHR (16) wire open?

--

Go to Step 15

Go to Step 9

13

Locate the open in the WHT (14) wire between the fuel pump, the sender connector, and ground G400.

Is the WHT (14) wire open?

--

Go to Step 15

--

14

  1. Disconnect the fuel pump.
  2. Place the ignition switch in RUN.

Does the fuel gauge indicate full?

--

Go to Step 6

Go to Step 12

15

Repair or replace the wire.

Is the repair complete?

--

Go to Step 1

--