Tuesday, July 10, 2018

How to check if Hondash will work with my ECU?

Follow these simple steps to determine whether or not the Hondash will work with your ECU.

1. 3 pin or 5 pin diagnostics connector

All Honda car models produced in 1992-2001 (OBD1 '92-'95, OBD2A '96-'99, OBD2B '99-'01) that use the 3 pin or 5 pin DLC diagnostics connector, are compatible with Hondash. 
If you can locate the 3 pin or 5 pin diagnostics connector in your car (locations described here), then your ECU is compatible

3 pin DLC connector
5 pin DLC connector

3 pin connector can have either 2 or 3 wires, 5 pin connector either 3 or 5 wires, depending on the car model and build year.
In case of 5 pin connector, the communication wire (purple wire in the picture, color may vary among car models) must be present in the connector. The "5 to 3 pin adapter" (sold separately) is required in order to connect the Hondash interface.

2. OBD Compatibility table (optional)

If you've already located the 3 pin or 5 pin diagnostics  connector, you may search the OBD compatiblity table for your ECU to check if it was already tested.  Please note that some ECUs are still missing in the table, but if the 3 pin or 5 pin diagnostics connector is on-board, they are compatible.

3. DLC Connector 3 pin / 5 pin voltages

You may also check the voltages on the connector pins, to determine its health status. There should be a 5V (communication wire) pin (with ignition switched on) and a 12V (power source wire) pin.
3 pin connector voltages
5 pin connector voltages

In case you're not getting 12V voltage on power wire, you should check for blown fuse (Under hood fuse/relay box, nr.43, 7.5A, ceiling light/cargo area light/DLC connector/Power antenna).
OBD1 without power wire
Some OBD1 cars ('92-'95) don't have the power wire in the DLC connector. Guide on how to wire custom power source can be found here

4. Aftermarket / chipped ECU

If you're using aftermarket or chipped ECU, please read this post about Aftermarket / chipped ECU to determine the compatibility by yourself. 

5. Modified ECU - Immobilizer Off

If your ECU was modified with IMMO OFF or similar procedure to disable the immobilizer on hardware level, your ECU might not work with Hondash as we've already seen in two instances involving immobilizer mods. This mod seems to disrupt internal communication and communication on DLC port, preventing from sending or receiving valid data.

6. Engine swap

In case of cars with swapped engines which use conversion harnesses (OBD2A to OBD1 or vice versa), the communication with ECU may not work correctly if the wiring is not done properly. In that case you have to make sure that the communication 5V wire (K-line) in the DLC diagnostics connector is correctly connected to ECU pin (K-line) by tracing it all the way to the ECU connector pins, using a pin-out diagram for the ECU as your reference.