Help Needed with Temp guage, T3 engine in ED XR8

[Eaturbo]

As title says i am having trouble getting the temp guage to work in my ED XR8
I am running the AU T3 TE 50 engine and wiring in an ED XR8. I can find the wire going from the Temp sender to the ECU but there must be a wire going from the ECU to the Dash or BCM. I tried tapping straight into the wire at the ECU which is pin 38 but no good. I am not sure if the AU and ED use a different type of temp guage. I can not find anything on the AU BCM or Dash wiring showing a wire to run the temp guage. It shows a few wires on the Dash wiring saying to EFI section than on the ECU wiring it shows 2 wires going into the ECU but it does not say what they do. I can get the ED temp guage to work by grounding it and it will go to full hot so it works. Someone out there must know something about these dam temp guage wiring. I would hate to trouble shoot an AU with a temp guage problem. Any help would be a big help to my poor brain. Thanks Shane

[superroo]

Engine temp comes via serial communication from the ecu, which is then deciphered by the cluster.

Cheers

[Eaturbo]

Originally Posted by superroo

Engine temp comes via serial communication from the ecu, which is then deciphered by the cluster.

Cheers

Thanks for your post as it seams you are it. Are you saying that there is no way to get my ED temp gauge to work from the AU system. I thought the temp sensor might run the ED gauge but it sounds like the gauges run from different types of inputs. I might need to fit an ED temp sender somewhere just to run the guage. Thanks again, i knew that someone would know how it all works.

[GreenMachine]

Pretty sure AU temp gauges are just idiot lights - they only have "normal" and "overheat" functions - Try an EB sender in the AU block, I'd imagine the threads on the fitting would be the same.

[superroo]

I think you could, but for that my suggestion for that would be to run a hidden au cluster or make a mutant ed/au cluster to run the temp.

But running a second water temp sensor is the easier solution.

Actually thinking about this, can you have the ecu flashed to read a different temperature and tap off this sensor for the cluster
E.g. the ED sensor may make the AU computer read 60 deg when it's 20 deg, but make the cluster work correctly.
Have the computer flashed to adjust the cold start parameters, so while the absolute number is wrong, it is the right temp?

Cheers

[AMB]

The temp sensor should be the same ED to AU if they work the same as the I6 engine. The sensor is just a resistor that changes resistance with temp. EF and AU sensors look different, but the resistance at different temps is exactly the same -so I've got a AU2 engine in my EF, using the AU sensor, no problems. Wiring the sensor (2 wires), one wire goes to the ECU temp sensor input (you already found that one), the other wire goes to the sensor ground (all the sensors use the same ground wire). No need to worry about the signal between ECU and gauge, unless you have done something to the existing loom?

[Eaturbo]

Originally Posted by AMB

The temp sensor should be the same ED to AU if they work the same as the I6 engine. The sensor is just a resistor that changes resistance with temp. EF and AU sensors look different, but the resistance at different temps is exactly the same -so I've got a AU2 engine in my EF, using the AU sensor, no problems. Wiring the sensor (2 wires), one wire goes to the ECU temp sensor input (you already found that one), the other wire goes to the sensor ground (all the sensors use the same ground wire). No need to worry about the signal between ECU and gauge, unless you have done something to the existing loom?

Thanks for your reply, Not sure what you mean by " No need to worry about the signal between ECU and gauge, unless you have done something to the existing loom?" The EF/L dash ran a small microprocessor which controlled the dash like the AU does. The ED has the old style dash which uses normal gauges and sensors. The signal the temp gauge gets from the ECU is different than the signal the temp sensor sends. If you look at the earlier falcons they all ran 2 sensors, one for the ECU and one for the temp gauge. I think i might need to fit an ED V8 temp sensor somewhere for the gauge only. What do you think, does this sound right or not too you

[AMB]

I'm not familair with the ED v8, I'm just trying to be helpful by thinking things through. I think you are saying that the ED V8 has 2 coolant temp sensors, one for the ECU, and another one just to run the dash temp gauge. If that's the case then yeh you may need another sensor like you said. That would mean you have a sensor connector somewhere not plugged into anything. All repair manuals will tell you what the coolant sensor resistances are at different temps, so easy to compare ED and AU sensors, to see if they are compatible.

[Eaturbo]

Originally Posted by AMB

I'm not familair with the ED v8, I'm just trying to be helpful by thinking things through. I think you are saying that the ED V8 has 2 coolant temp sensors, one for the ECU, and another one just to run the dash temp gauge. If that's the case then yeh you may need another sensor like you said. That would mean you have a sensor connector somewhere not plugged into anything. All repair manuals will tell you what the coolant sensor resistances are at different temps, so easy to compare ED and AU sensors, to see if they are compatible.

I do appreciate your help mate, I dont have any spare sensors as the engine is an AU engine an only has one sensor like the EF/L. The ED engine had 2 sensors. I sort of worked it out after reading your post and when i checked the wiring diagram i found the 2 sensors had different wire colours. I was just looking at the sensors and seeing one wire but i did not compare the colours. There is 2 diagrams showing 1 temp sensor, 1 for the dash and 1 for the EFI and i thought they were the same sensor but it was actually 2 different sensors. The AU is the same only it uses the same sensor. Thanks for your reply as it has helped me figure it out.

Regards Shane

[AMB]

No worries, let us know how you go. Just thinking if it would possible to use the one sensor for both the ecu and gauge, you would need to put diodes on both sensor wires, so that the current coming from the ECU and gauge can only go to earth, and not go back up the other sensor wire.