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Home >> Pontiac >> 2005 >> Sunfire Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 68 (Automatic Transaxle - 4T40-E/4T45-E Diagnosis (DTC P0748 (3.4L) To P1887)) >> Diagnostic Information and Procedures >> DTC P0748 (3.4L) >> Test Description

Test Description

WARNING: This page is about a different car, the 2004 Pontiac Grand Am and 2004 Oldsmobile Alero. However, it is still accessible from the selected car via links, so may be relevant.

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

  1. 2:  This step verifies the ability of the PCM to command the PC solenoid valve.
  2. 3:  This step verifies that the automatic transmission wiring harness and the PC solenoid valve have correct resistance.
DTC P0748 (3.4L)

Step Action Value(s) Yes No
1 Did you perform the Diagnostic System Check - Engine Controls? - Go to Step 2  Go to Diagnostic System Check - Engine Controls in Engine Controls -3.4L
2 
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
    3. IMPORTANT: Before clearing the DTC, use the scan tool in order to record the Failure Records. Using the Clear Info function erases the Failure Records from the PCM.
  3. Record the DTC Failure Records.
  4. Clear the DTC.
  5. Start the engine.
  6. Using the scan tool, apply 0.1 amps through 1.0 amps.
  7. Observe the scan tool display.
Does the PC Sol. Actual Current vary from the PC Sol. Ref. Current by more than the specified amount?		 0.16 amps Go to Step 3  Go to Intermittent Conditions in Engine Controls - 3.4L
3 
  1. Turn OFF the ignition.
  2. Disconnect the AT inline 20-way connector. Additional DTCs may set.
  3. Install the J 44152  jumper harness (20 pins) on the transmission side of the AT inline 20-way connector.
  4. Using the DMM and the J 35616  GM-approved terminal test kit, measure the resistance between the PC solenoid valve high control and the PC solenoid valve low control circuits of the J 44152  .

    Refer to Automatic Transmission Inline 20-Way Connector End View .

Is the resistance within the specified range?		 3-7 Ω Go to Step 7  Go to Step 4 
4 Is the resistance greater than the specified value? 7 Ω Go to Step 5  Go to Step 6 
5
  1. Test the high control circuit of the PC solenoid valve for an open between the AT inline 20-way connector and the PC solenoid valve.
  2. Test the low control circuit of the PC solenoid valve for an open between the AT inline 20-way connector and the PC solenoid valve.
Refer to Testing for Continuity in Wiring Systems.Did you find a condition?		 - Go to Step 18  Go to Step 19 
6 Test the high control circuit and the low control circuit of the PC solenoid valve for being shorted together between the AT inline 20-way connector and the PC solenoid valve.
Refer to Circuit Testing in Wiring Systems.
Did you find a condition?		 - Go to Step 18  Go to Step 19 
7 Measure the resistance from the PC solenoid valve high control circuit of the J 44152  to ground.
Refer to Automatic Transmission Inline 20-Way Connector End View .
Is the resistance less than the specified value?		 1,000 Ω Go to Step 8  Go to Step 9 
8
  1. Test the high control circuit of the PC solenoid valve for a short to ground between the AT inline 20-way connector and the PC solenoid valve.
  2. Test the low control circuit of the PC solenoid valve for a short to ground between the AT inline 20-way connector and the PC solenoid valve.
Refer to Testing for Short to Ground in Wiring Systems.Did you find a condition?		 - Go to Step 18  Go to Step 19 
9 Measure the resistance between the PC solenoid valve high control circuit and all other terminals, except the PC solenoid valve low control circuit, of the J 44152  .
Refer to Automatic Transmission Inline 20-Way Connector End View .
Is the resistance less than the specified value?		 10 Ω Go to Step 18  Go to Step 10 
10
  1. Disconnect the J 44152  from the transmission side of the AT inline 20-way connector.
  2. Install the J 44152  on the engine side of the AT inline 20-way connector.
  3. Disconnect PCM connector C2. Additional DTCs may set.
  4. Using the DMM and the J 35616  , measure the resistance from the PC solenoid valve low control circuit of the J 44152  to ground.
Refer to Automatic Transmission Inline 20-Way Connector End View .Is the resistance less than the specified value?		 10 Ω Go to Step 11  Go to Step 12 
11 Test the low control circuit of the PC solenoid valve for a short to ground between the PCM connector C2 and the AT inline 20-way connector.
Refer to Testing for Short to Ground and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 21  -
12 Using the DMM and the J 35616  , measure the resistance of the PC solenoid valve low control circuit between the J 44152  and the PCM connector C2.
Refer to Automatic Transmission Inline 20-Way Connector End View .
Is the resistance less than the specified value?		 10 Ω Go to Step 14  Go to Step 13 
13 Test the low control circuit of the PC solenoid valve for an open between the PCM connector C2 and the AT inline 20-way connector.
Refer to Testing for Continuity and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 21  -
14 Using the DMM and the J 35616  , measure the resistance from the PC solenoid valve high control circuit of the J 44152  to ground.
Refer to Automatic Transmission Inline 20-Way Connector End View .
Is the resistance less than the specified value?		 10 Ω Go to Step 15  Go to Step 16 
15 Test the high control circuit of the PC solenoid valve for a short to ground between the PCM connector C2 and the AT inline 20-way connector.
Refer to Testing for Short to Ground and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 21  -
16 Using the DMM and the J 35616  , measure the resistance of the PC solenoid valve high control circuit between the J 44152  and the PCM connector C2.
Refer to Automatic Transmission Inline 20-Way Connector End View .
Is the resistance less than the specified value?		 10 Ω Go to Step 20  Go to Step 17 
17 Test the high control circuit of the PC solenoid valve for an open between the PCM connector C2 and the AT inline 20-way connector.
Refer to Testing for Continuity and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 21  -
18 Replace the automatic transmission wiring harness.
Refer to Wiring Harness Replacement .
Did you complete the replacement?		 - Go to Step 21  -
19 Replace the PC solenoid valve.
Refer to Pressure Control Solenoid (PCS) Replacement .
Did you complete the replacement?		 - Go to Step 21  -
20 Replace the PCM.
Refer to Powertrain Control Module (PCM) Replacement in Engine Controls - 3.4L.
Did you complete the replacement?		 - Go to Step 21  -
21 Perform the following procedure in order to verify the repair:
  1. Select DTC.
  2. Select Clear Info.
  3. Turn ON the ignition, with the engine OFF.
  4. Select Specific DTC.
  5. Enter DTC P0748.

Has the test run and passed?		 - Go to Step 22  Go to Step 2 
22 With the scan tool, observe the stored information, capture info and DTC info.
Does the scan tool display any DTCs that you have not diagnosed?		 - Go to Diagnostic Trouble Code (DTC) List in Engine Controls - 3.4L System OK
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