tootrn

Has anybody had issues with scan tools communicating with the ECU. For whatever reason this problem occurred at the worst possible time. (Smog test) All the fuses are good, interior, exterior lights, cigarette lighter, radio everything works fine but after I connect a scan tool to the OBD 2 connector as so as the scan tool tries to establish communication with the ECU the immobilizer icon light in the clock lights up and I get a "Unable to communicate with the ECU" message. If I press the key fob button the light will go off for a millisecond then come right back on. I did the end all test, have engine running than connect scan tool, no go, the immobilizer icon light came on immediately. I should add that the no communication is with engine management only, there's still communication with ABS, AC/Heater and Alarm. When I ran a jumper wire on the 9 and 11 terminal on the immobilizer, which will end its link with the ECU, I lost communication with all systems. The OBD 2 connector wiring was checked and there's no issues there. Can something funny be going on with the DME relay to cause this problem?

Catorce

What scan tool are we talking about here? The one from the smog station or your own? If it is your own, many of them will not work with the DME. I have 4-5 different ones for that reason. What year is the car?

tootrn

I have the Durametric and Innova. I should have mentioned that they had worked before, then without any warning they both stopped working. I ended up bringing it to the dealer and they have the same problem. Thanks for your input.

Catorce

In that case I usually suspect a broken or bent pin on the OBD cable but since both tools don't work and the dealer has the same issue, it could be the OBD socket in the car itself that has a pin problem. Look for a broken pin in the OBD socket female connectors or one missing from your other plugs. Happens all the time.

If it was the DME itself the car would not run right. Unfortunately there is a lot of detective work to be done.