89' 740 GL Wagon still coding 1-2-3 after both ETC replaced

[POsubVolvo]

This is how I check my code: first I plug the prong into port #2 press the button for 1-2 seconds, let go and read the flashes. Currently port #2 is coding 1-1-1 = all clear. Then I plug the prong into port #6, for 1-2 seconds, let go and read the flashes. Currently it is coding 2-2-4 = ECT sensor missing or faulty. I then keep the prong in port #6 depress the button for more then 5 sec, let go, then wait for for the red light to show & while it is on, press the button again for more then 5 seconds, and let go. Then I disconnect the battery for a minute, reconnect the battery and check the codes in both ports. In port 2 , I get 1-1-1 =clear and in port #6 I get 2-2-4 = ECT sensor signal missing or faulty as per my code book. Hope this helps. Is there supposed to be voltage on both terminals of the ECT wiring harness? I gave you the wrong voltage readings in my last post. With the connector clip at the top the right terminal read 5.04 volts and the left read 7.0 volts. Any suggestions?

[billofdurham]

You are reading the codes correctly, forgive my doubting your ability.

You should have voltage at both terminals as one goes to the fuel ECU and the other to the ignition ECU. 5v is OK but 7v is slightly high.

The 2-2-4 code should clear when you press the button for 5 seconds and disconnect the battery. It should only re-appear after you try to start the engine. Try to erase port 6 again but disconnect the battery for a slightly longer period.

Bill.

[POsubVolvo]

No forgiveness needed, I'm new at all this, remember. I will try to clear the codes in port #6 again tomorrow and keep the battery disconnected for 15 min just to be sure. I'll let you know what happens. Thanks

[POsubVolvo]

I'm still working on the cold start problem. I will replace the ECT one more time since I may have the wrong after market blue bottomed ECT. I am also pulling a radio relay from my "for parts" 740 Turbo to put in the 740 GL to see if this will help the cold start problem. After properly clearing all the codes, they currently code: Port #2: 1-2-3=ECT sensor, 2-3-2= Lambda adjustment, and 1-1-3=fuel injectors. Port #6 now codes 2-2-4=ECT sensor all 3 checks.