OBD 20 pin & OBDII issues

[vroomvroomman]

Hi all,

I've got a check engine light on my 1999 1.9, and I had difficulty connecting to either OBD ports. At first I tried the OBDII in the cabin, but that didn't work. Then I tried using a 20 pin adapter to OBDII in the engine bay, and that also didn't work. Didn't matter if I had my ignition on or engine on, never wanted to connect. Then one time when I was trying to connect it and it didn't work, I turned the key ignition back to the first position (not fully off, though I believe it doesn't make a difference), and then it suddenly connected. That method works pretty much all the time, without fail. Whenever I try connecting normally, the scanner just can't seem to find a handshake with the car.

Does anybody have any idea why this could be happening, and how to fix it?

 

[mwpe]

Check that the pins on the connectors are clean, I had a probem with connecting once but a squirt of switch cleaner solved it.

 

[vroomvroomman]

Check that the pins on the connectors are clean, I had a probem with connecting once but a squirt of switch cleaner solved it.

Thanks for the suggestion! I did try that, however no luck. The only way to actually get a connection seems to be by switching the ignition from position 1 to 2 a couple of times.

 

[ChrisD]

I suspect that this is more to do with the scan tool that you are using. The comms wake up timing sequence is quite critical and may be being affected by bus loading and other modules interacting when awake. If you have a method of accessing the diagnostics then stick with it. If you need more functionality (e.g. live data capture with the engine running) then maybe try another tool.

 

[vroomvroomman]

Scan tool seems to be fine, i’ve used a carista and a generic obd2 tool. It seems to connect fine now though, so maybe it just needed a little push after 25 years or so . Thanks for the suggestions!