Where to find the part number on an ECM, TCM, climate control or window switch

On automotive electronics, year, make and model is a starting point, not an answer. The part number is the answer. Here is where to find it on the parts we sell most.

Engine computers (ECM, PCM, ECU)

Look for a printed or foil label on the largest flat face of the case, usually near the connectors. Domestic modules often carry a manufacturer number plus a separate calibration or "broadcast" code, and both can matter. If the label has faded, the number is sometimes stamped into the housing itself.

Transmission computers (TCM, TCU)

Frequently mounted inside the cabin behind a kick panel or under the dash, or bolted to the transmission itself. The label is usually on the side facing outward once the module is unbolted. If your vehicle has no separate transmission module, the shift logic is inside the PCM.

Climate control and A/C heater panels

The number is on the back of the unit, which means pulling the trim bezel and the panel out of the dash. This is worth doing. Climate panels change with trim level, single zone versus dual zone, and manual versus automatic climate control — all of which are invisible from the front.

Master window switches

Lift the switch assembly out of the door card and turn it over. Alongside the part number, count the connector pins and note whether your vehicle has power folding mirrors, memory seats or auto up/down on more than one window. Those options change the part.

What to record before you shop

• The full part number including any suffix letters
• Any secondary calibration or software code on the same label
• Connector count and colour
• Your VIN
• Engine size and transmission type

Can't get to it?

If the module is buried or the label is unreadable, your VIN is the next best thing. Send it to us and we will identify the correct unit for you.