Does a Yamaha 150 hp V6 Saltwater Series II fuel-injected outboard have a diagnostic port?
I've got a Yamaha 150 hp V6 Saltwater Series II with fuel injection and want to check it for fault codes. Does it have a diagnostic socket under the cowling, and what reader do I need?
Answer
Yes, the Yamaha 150 hp V6 Saltwater Series II with OX66 fuel injection has a connection for reading the engine's self-diagnostic codes. It normally uses Yamaha's diagnostic indicator and the correct test lead, rather than the laptop diagnostic system fitted to later engines.
Check the model plate
Record the complete model designation and serial number from the identification plate on the transom bracket. The Saltwater Series II lettering on the cowling identifies an engine family, but does not tell you which diagnostic equipment fits.
This description usually refers to the conventional EFI two-stroke OX66 V6, commonly found in late-1990s and early-2000s installations. US-market model designations often include SX150 or LX150, though names and production dates vary by market.
- OX66 EFI: electronically controlled fuel injection with an older self-diagnostic code system.
- Carburetted 150 V6: may look similar, but OX66 diagnostic instructions do not automatically apply.
- 150 HPDI: a different direct-injection engine with different diagnostic arrangements.
- F150 four-stroke: a separate engine family; its diagnostic instructions do not apply to the older V6.
A cable advertised as fitting "Yamaha 150" may be intended for a completely different engine.
Find the diagnostic connection
On an OX66, look under the cowling for the diagnostic connection in the engine wiring harness associated with the ECU. This small service connector is normally protected when unused. It is not a car-style 16-pin OBD socket.
Its exact position, connector arrangement and access vary by model and year. Check the wiring diagram and component-location drawing for your full model code before unplugging anything. Several nearby connectors can look like the right one.
- Switch the ignition off and remove the cowling.
- Identify the ECU and follow the service manual's drawing to the diagnostic lead.
- Check the connector for corrosion, damaged terminals or a missing protective cap.
- Connect the specified indicator and adaptor with the ignition off, then follow the manual's test sequence.
Keep hands and test leads clear of the flywheel and throttle linkage. Supply cooling water whenever a test requires the engine to run.
Choose the correct reader
The normal OX66 procedure uses a Yamaha diagnostic indicator, often called a diagnostic lamp or code tester. Its signal sequence gives numerical diagnostic information, which you read using the chart in the model's service manual.