Ok guys. I have searched this many times in the past and it is really bothering me now. I have no CEL whatsoever. I have an S5 TII. I have replaced the ECU (EM) module before and still no CEL. I have checked the bulb in the display and everything is OK. Is there an output wire that controls the CEL and where does it come from? Is there a pin number that I can check? Right now I am trying to check codes and can not. My voltage is low at the 2F and 2G pins for the TPS as well as other pins. I am getting no spark and no injector click when turning the CAS by hand. The CAS and the TPS check out in spec. Can someone suggest something?

 

The car has traits of the ECU not getting any power. ECU outputs the trigger for the coils and the gnd pulse for the fuel injectors. No power to the ECU....no worky anything engine related,.

Download the series five FSM. Go to CONTORL UNIT. It has what each pin on the ECU plugs does in life. One of the pins outputs a gnd signal to the check engine light. That's one of the first pins on the ECU plug.

 

It seems that very little if any power is getting to the ECU. All of my voltage readings that I am getting are very low. They are there, but very low. I was running fine and trying to adjust the TPS when it shut down all together. As I was messing with the wire connector at the TPS, it started to cut out like the connection was loose and then the next time I tried to start it, nothing at all. I have checked the connections now, but still no go.

 

1A is from the battery via the room fuse in the engine bay which in turn is fed by the BTN fuse in the engine bay.

1B is fed if the key is to ON and the Main Relay pulls in. The EGI fuse feeds the pin 1B and the ENGINE fuse in the interior feeds the coil of the Main Relay.

 

maybe your battery bit the dust

 

Battery is a little less than 12v and I have power at Pin 1a and 1B as expected. Could it be a bad CAS?

 

Not likely the CAS.

1A and 1B should be very close to batt voltage. Like batt voltage is 12vdc, then the other two should be 11-12vdc. Closer to 12.

If I had close to 12vdc on 1A and 1B, then I'd put the key to ON and backprobe the REF VOLTAGE output wire which is shown in the Control Unit section of the FSM. Should be 4.5 to 5vdc. IF it's 1 or 2 volts....ain't no damn good. Either ECU bit the dust or one of the sensors that gets REF VOLTAGE is dragging it down so that nothing works.

All the above wires should be backprobed with the connector ON the ECU. Plug off the ECU is meaningless.