Duramax Swap Diagnostic Form

We can not begin a discussion about troubleshooting your first start without this form completed. Please fill out all the fields accurately and supply required photos.

If you have more than the size limit of photos or have filled out the printable form and wish to send us a scanned copy, please send to support@dmaxswap.com. We will not reply without this information.

*** It is very unlikely that the harness and modules are the cause of no start problems. In our experience, a no start is due to fuel supply or injection system problems. Also, be sure to check your grounds and battery connections.

Printable Version

Customer Details

means required

Full Name

Email Address

Contact Number

Order Number


RPO: ECM - TCM, if your transmission isn't listed, don't worry, you can enter it below.

Step 1: Go to Scanner Live Data Screen (From OBD Port scanner only. No volt meter tests or guessing)

Step 2: Enter the Actual Values from Scanner Live Data below.

Voltage - Key-On

Voltage - While Cranking

Lift Pump Pressure
We always recommend a lift pump for fuel system health and perf.

Accelerator Pedal Position (APP)
Can be a percentage or voltage

APP change with Pedal Movement?
[radio* app-move default:2 "Yes" "No"]

Manifold Absolute Pressure (MAP)

Mass Air Flow (MAF)
Or change when Cranking?

Intake Air Temp (IAT)

Coolant Temp (ECT)

Engine Oil Pressure (EOP)

Or change when Cranking?

Fuel Rail Pressure (Desired)

Fuel Rail Pressure (Actual)

Fuel Rail Pressure (While Cranking)

Fuel Rail Temp (FRT)


Should be 150 during cranking

CAM Signal ā€“ (advanced scanner required)

Step 3: Scan for fault codes.

If codes are present list them below in order with the number - description. Listing in order is important as they are prioritized in the ECM from most to least important.
Top OBD ā€œPā€ Fault Codes - Description (required)

Photos (limit 10mb total) - Please Include Photos of your complete installation, including Upper engine harness connections (2 bale connectors).

Additional Details