DF140 Check engine light

[kemarine]

Ok so I had a suz 140 come in with a check engine light on. Thought it was just the oil change reminder so i reset it and the buzzer went away but the light stayed. I hooked the computer to it and doesnt show any codes other than a gradient overheat a while back. I tried a new tach because the light was very dim so thought that maybe it was a faulty gauge but it still came on. Ran it again with a new harness and new gauge and still came on. Doesn't make sense to me since computer shows no known problems... any clues would be very helpful.

[keakar]

my first thought is a sensor is bad but still working.

ohm out all the sensors to find the bad one

if they all check out ok then i would have a big question mark about the ECM but its too expensive to change out just to see if there is a possible short in it somewhere

[kemarine]

Thanks yeah my next step was check the grounds and sensors because the light is dim sometimes and then it flickers in and out and gets brighter, but then sometimes it is steady and bright. I have only had to replace one ecm and im definately not spending any more money on diagnosing.