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Good evening ! new to this site .. i have a 2008 suzuki xl-7 with no 5 volt reference on pin 45 on the ecm . This causes a no start condition and several codes because they share the same pin . I figured the ecm was bad .. but a replacement gives the same codes and no start . I cut the wire at the ecm and no voltage is there . so i jumpered off of pin 39 and the car attempts to start . What input tells the computer to turn on the 5volt reference to this pin ? This is actually a general motors product .
Are you working off of a wiring diagram that you can share? How do you know pin 45 is a 5v ref and what circuits is it supplying. If you're getting 5v from pin 39 it maybe a thermistor circuit and you cannot share that 5v with a pot. The cam and crank supply the signal for ignition and injectors. Never worked on a Suzuki but makes no difference, the circuits all work the same. I would like to help you but need more to go on.
"an open mind let's knowledge flow in and wisdom flow out for a man who has neither never listens to those who have both".
Being wrong doesn't bother me, it's being right and not understanding why that does
i have a gm printout of the ecm that i got from a friend . Pins15 -39 and 45 are 5 volt references .Pin 45 out of the ecm has 0 volts. I used #39 because it had power .The circuit fed by 45 supplies 5 volts to the crank sensor and the throttle position sensors. So i had codes p0122 p0222 and one for the crank position sensor. I am new to gm systems but i think this computer was used in cadillacs ,saturns.chevys. and others...so it is not really a suzuki
And i did the parts cannon. .lol...ecm --crank sensor--throttle pedal.... with the same results ..till i got the printout and realized i had no 5 volt reference on pin 45
You could have a bad replacement ECM... it happens all the time. When you cut the wire at pin 45, if one of the sensors that it supplies the 5v to was shorted you would have gotten the 5v back. Seeing that did not happen and you probed pin 45 at the ECM and still no joy seems likely a bad ECM. Before doing anything else, check the pin on the harness side for 45 really close for corrosion, bent pin, loose pin, female portions of the pin open too far not making good contact. One last thing... what ever shorted that 5v regulator could still be present and when you plug in a new ECM you'll take out the regulator again. The 5v regulator is pretty well protected even when shorted they usually come back once the short is corrected.
Can you post or message me the diagram you have?
"an open mind let's knowledge flow in and wisdom flow out for a man who has neither never listens to those who have both".
Being wrong doesn't bother me, it's being right and not understanding why that does
i checked all power and ground connections to the ecm and everything seems ok . And when i steal 5volts from another pin ... the volts stays at 5v ,so i dont have a short. But i am definitely missing something .
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