Sunday 18 January 2015

Troubleshooting OBD1READ :: determine if the ECU is sending data

Testing if your Toyota ECU is outputting obd1 data is easy and requires only a digital voltmeter and jumper wire. Here's how to do this test.

-the ignition key must be at ON position and the engine not running.
-make sure there is no jumper wire between E1 and TE2 (no continuity present)

using the Voltmeter you must read the voltage between VF1(positive probe) and E1(negative probe). You should see a flat reading near 0V like in this video.

-Install a jumper wire between E1 and TE2.

using the Voltmeter you read once again the voltage between VF1(positive probe) and E1(negative probe). This time you will see an irregular fluctuating reading between 0V and 5V. this means a data stream is sent through the VF1 pin.
Using this method you were able to determine if your ECU is sending data that can be read for an OBD1READ device.


  1. Hi, I hope you can give me some advice. On my US-spec 1995 Land Cruiser with a 1FZ-FE inline 6, I do not have a VF1 terminal at all. My diagnostic box has only the following terminals populated: TB, TE1, E1, AB, TS, TC, and WA and WB that are jumpered together. Is there any way for me to adapt this box to the TOYOBD1 that I just bought, or am I going to have to solder another box and wires onto the ECU? Thanks in advance, Chris.

  2. Hi, sorry for the extremely late reply.
    since it is a 1995.
    if there is no VF1 or VF2 terminal it is most likely an obd2 engine.
    TE1 AND E1 are used to lock ignition advance (AB,TC,TS)are there for triggering other ECUs error codes (SRS,cruise control,etc) (WA-WB) is an ABS jumper that should remain there is one want's the system to fully work. since yours is almost fully populated I then suggest growing another one.