69 replies to this topic

[minisilverbullet]

I have tested the voltage at all the pins (with ignition on)

 

As you can see - no voltage at pin 16, i also followed flyscots advice at measure voltage across the connector also 0v and then with the sensor in place across the two wires = 0v.

 

The only thing i though was odd was at pin 5 (green and blue wire) the voltage alternated between 1 - 8 v. 

 

 

[minisilverbullet]

and then for reference:

 

[minisilverbullet]

Also I wonder if there should be a 12v supply from pin 28 "supply from main relay"?

 

Answered this myself, there is a 12v supply on pin 28 when the engine is running.   

[minisilverbullet]

I have also just followed one of sprockets  posts for testing the o2 sensor. with the voltmeter set to 1.5v, the positive on the grey (pin7) and the negative on the green/grey (pin18) the voltage changes pretty rapidly between 0.13 and 0.05. to simulate lean conditions i removed the vacuum to the edu and the voltage dropped further to around 0.02.  So i guess i can rule the o2 sensor out ( i thought it might be at fault and initiating the limp mode, and then effecting the supply to the iats).

 

Another thing with the IATS when i use the code reader with the sensor connected i have value of 35 (suggesting limp mode). when the sensor is disconnected i get a different reading? isn't that strange? 

[xrocketengineer]

Pin 5 goes to the temperature gauge on the dash. On the other side of the gauge is the voltage stabiliser which I believe is mechanical and oscillates to regulate the voltage. Maybe that is what you are seeing.

So, if you found 12V at pin 28, then Rover Mini specific wiring diagram is wrong. It shows pin 29 as relay power and 28 as earth.

The different temperature readings with the IAT sensor plugged in or not, are probably due to some residual voltage left (from the 5V) in the ECU that disappears when the sensor is plugged in. I essence, the sensor act as short to earth/ground and the voltage goes away.

 

Craig, you have done an excellent job troubleshooting this issue by being very methodical, logical and thorough, even when I misled you. dbcool20 has been very helpful too by confirming information on a good system.

 

Cheers to you guys,

Ivan

[minisilverbullet]

One last thing before I send the ecu of to England.

When I was testing the the wiring I could hear a clicking, I narrowed it down to the stepper.it was randomly clicking over the 15 minute period I was resting the wiring.

When the car is running badly ( it is an intermittent fault) I can see the pin on the stepper moving almost it's full length. When it retracts the car nearly stalls. Then the pin comes out and stops the car stalling. This in and out is continuous.

I have a spare stepper motor, I wonder if I should change it over, or will I wasting my time?

[xrocketengineer]

I would wait for the repaired ECU. It might take care of that too.

[FlyingScot]

The MEMS will try to keep the car running almost come what may what you are seeing is it adjust the stepper (and probably the timing too ) to keep her from stalling.

FS

[minisilverbullet]

Thanks for the help guys! 

Really appreciated. 

 

ECU is now with the Swedish post office and on route to England.  

[xrocketengineer]

Let us know how it goes when you get the ECU back.

[dbcool20]

Yes. I really hope this will sort your problems. please keep us informed 

[minisilverbullet]

Received an email from Autotek who have my ECU ( I only posted it on Friday, from Sweden)

 

The fault: 

 

"This Engine ECU has been tested several times and found to be faulty. The internal power supply circuit has been overloaded and the 5 volt output rail has failed. Refurbishment is required."

 

the damage - 238 pounds

[FlyingScot]

Ouch! Well it confirms what you proved yourself Craig; no 5V supply.
Nice service from Autotek, need to remember that.

FS

[xrocketengineer]

Mine was £120 plus shipping which was pretty steep but that was 5 years ago. That was for rebuilding the ECU and removing the immobiliser code on an MNE101170. Someday, I will have my original MNE101070 rebuilt too.

Edited by xrocketengineer, 22 July 2014 - 04:58 PM.

[minisilverbullet]

I called them and enquired to a possible cause, and they directed me towards the common earth of the sensors. Though, as tested above that seems fine.