GM Automatic - Auto Repair Codes

Scan Tool for Codes and Live Data for your GM Transmission from $199 USD

The information below may apply to GM and many other models

Step 4

GM Trans Code Reading

Connector Diagram

Auto Repair Manual - How to read codes (No Special Tools Needed)

1 Apply parking brake, and put transmission into 'Park'.

2 Start engine and leave it running.

3 Connect the black connector using your own wire link, (Click here for details) , as shown in the diagram to your left.

4 For the Green connector, connect an LED tester or Voltmeter to terminals 'A' & 'B'. (Click here for details) 

5 The fault codes will be shown on the LED tester or Voltmeter connected.

6 Turn ignition ON

7 Read codes as described in the Code Format Description below.

8 Press the continue button to enter the code numbers and get the code description.

Code Format Diagram

Code Format Description

• Each code consists of two groups.

• The first group of flashes indicate the 'tens' digits.

• The second group of flashes indicate the 'ones' digits.

• A short pause separates 'tens' and 'ones' digits.

• A long pause separates each trouble code.

• Code Format Diagram shows code No. 21.

To move to the next screen click on the Continue button

 Continue > 

Note on Example Model(s): GM
The example model(s) shown, GM for this auto repair service are only an indication to help you. There may be many other models that apply to this connector. Click above link to see the complete vehicle coverage list.