Has anyone ran into being unable to pull trouble codes? This is on my '89 N/A. Used to work just fine. Now when I try to pull codes when I turn the key on after grounding the check connector the CEL comes on like it used to. Then it goes off like it should IIRC. Then it comes back on and stays on. I don't believe the fuel pump is running but I will check to be sure. IIRC it doesn't run with the check connector grounded. Curious if anyone has seen this before?

 

I vaguely recall once seeing a question similar to yours on the forum. The answer was that a continuously glowing CEL, while green 1-pin check connector was grounded, meant that the ECU was bad. You might want to reset the ECU and try this again.

The engine should run with the green 1-pin check connector grounded. That's what you do prior to checking the ignition timing. From '89 FSM: "To check or adjust ignition timing ground the test connector (Green: 1-pin) to the body with a jumper wire."

 

Great. Though the car seemed to run fine till yesterday. I discovered I couldn't pull codes 6 to 10 months ago.

It will, or should at least as that's the procedure I used last time I checked timing a couple years ago. Fuel pump must reactivate once you start cranking, or I dreamed it shuts off.

The car did develop an issue yesterday but I wanted to keep that separate from this thread so I'll not go into detail here other than I don't think I'm in limp mode.

 

you might have a loose/ corroded wire. You could check for continuity of the wires involved.

 

I haven't check continuity yet but the light doesn't go off at all without the connector grounded. It seems to at least recognize that the connector is grounded. I will check into it further though.

 

Check for continuity of 1D(Y) and 1F(Y/B) from end to end.

 

I have been able to pull codes now. Maybe I was doing it wrong. Here's how I was doing it:
Ground green check connector, then turn ign. switch to on/ run. No codes. one flash then on continuously.

Here's how I get it to work:
Turn ign. switch to on/ run, then ground the green check connector. Code flashes like expected. It will also flash the code while running if the check connector is grounded.

The confusing thing is I don't remember turning the key on first before, but maybe I did. Either way it works now.