Hello everyone,

a friend of mine has 2003 Accord, K20A6 engine, and has a strange problem. It won't start, immobilizer light keeps flashing and can't do diagnostic. We tried hooking it up to several interfaces (ELM, Bosch KTS, Launch etc) but neither one of those can't access car's ecu. The biggest problem is with wiring. According to Honda ESM manual, light blue wire, which is K line should go to E27 on ecu, but in this car it goes to A30. We checked all the wires around immobilizer, and it's all as in manual (wires that go from ignition to imoes unit), accept for the wires between immobilizer control unit receiver and ecu. As with K line, wires go on a different pin on ecu. We checked on the plate under the hood, the engine is K20A6. Does anyone know if there are different ecu's, with different pinout which were used in K20A6 engine?

 

K20 in a 2003 Accord means you're not in USA. Where are you? OBD-2 wiring is a USA thing, but car companies use it elsewhere for convenience. But maybe not EVERYWHERE... ?

 

Sorry, I forgot to mention that it is from Europe, UK to be specific. Differences between actual wiring in the car and in the manual are so great, that there's no way that someone messed with it and made error. That's why I think there might be some other version of ecu.

 

This is based on my TSX which is similar to the european type r accord.

When a good key is inserted into the ignition and switched to the II position, the key light comes on for two seconds, then turns off. When you turn the key off, the light blinks five times.

If a non-functioning key is inserted, the light comes on for two seconds, then keeps flashing. Sounds like this is your problem.

The first thing in the shop manual is to make sure the battery is charged. You may want to hook up jumper cables to another car and see if this solves the problem.

 

@PAhonda We've tried new battery etc. I forgot to mention that friend has a small car mechanics workshop, so we're not exactly dummies What we wanted to do is check wiring wire by wire, but we don't know by which wiring diagram to go. Even if the key code is not good (but it is, specialist for keys did the diagnostic), we should be able do do basic diagnostic through obd2 port.

 

Problem solved. Some connectors are mislabeled, namely A and E connectors are mixed up. Everything works now...

 

I thought that the ECU connectors had different sizes to avoid mixing them up. Glad you sorted it out and for posting the solution.

 

90% of connector are unique, but some are identical with others. Once we figured out that A connector in the car is actually labeled as E in service manual, and E as A, it was just a question of following schematic diagram. Problem was in faulty contact in one of the connectors under the dashboard. Because of it, there was no power supply to ecu, coils, injectors and few other things. Once we sorted it out, car started without any problems.