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My ECM's 5V reference falls to 1.5V with the fuel level sender plugged in. (Just replaced - old one was open.) I get an Ohms reading of 70 Ohms at the ECM connector (disconnected from ECM) with all circuits connected. That means I'm only drawing about 75 mA from the reference but it falls to 1.5 VDC. I haven't taken an Ohms reading without the fuel level sender disconnected since the reference comes back to 5VDC. (70 Ohms seems reasonable with less than half a tank of gas- the sender is 40 Ohms at empty.)
WHAT IS CURRENT RATING FOR THE 5 VOLT REFERENCE CIRCUIT??
If no one knows can someone with a 96-98 Tracker, disconnect the center connector (the ECM has three) from the ECM and take an OHMs reading from your reference circuit (gray/red wire) to ground (I used the steel dash plate directly under the steering wheel).
THANX . . . Hoping it's NOT the ECM . . . but it looks bad.
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10-25-2015, 03:10 AM
(This post was last modified: 10-25-2015, 03:27 AM by fixkick.)
are you talking the gray-red wire from ECU? +5vdc refr.
it dont run take level
just tps, EGR map, and tank pressure (not level)
the ref, is s power regulator and we can ohm that out. its undefined turned off, and when on , you can ohm power busses...
it say 100 ma? or up to 250ma, for current, max , just a guess.
but maybe 25m max for the 3 sensors?
the TPS uses 0.003 amps 3mA)
what wire are your touching. name color part and pin numbers.
the actual fuel gauge, sender
gets power from the cluster power;s internal 12v power buss.... its not 5v at all.
cluster 12v to meter, and meter to ground
then the meter is tapped, and goes to the tank sensor.
the varying voltage at the sender to gauge tap, is measured by the ECU and only flags, low fuel. there is no 5v here.
if 5v really drops? unplug the egr map then the tank pressure sensor, if 5vdc returns the one pulled is bad if it restores, as you know , im sure....
the ecu senses the fuel level on the yellow-red wire,
i need wire colors to answer clear. or pin numbers of devices.
http://www.fixkick.com
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Thank you for the reply . . . Yes the gray-red wire, inside row near the middle of the connector on the middle ECM connector (my ECM has three). I cut it (couldn't get the pin loose) so I could take the resistance readings and see the voltage out of the ECM at the same time. The 100 mA to 1/4 Amp current capacity makes sense. My manual (wire diagram) says the sender, but the tank pressure sensor makes sense as it would need a more accurate voltage to meet the emissions standards. I am not near the vehicle but I will check that tomorrow. With the tank back in place I can't follow the wires, so I went by what the diagram said. The explanation of the fuel gauge will also help as the new sender (old one was definitely an open circuit) didn't fix the dead fuel gauge either (it never moves and always reads below empty). It runs MUCH better with the reference restored to the map and egr. I also replaced both O2 sensors which appeared original from 97 (the previous owner had rounded them both completely off trying to get them out.) Bad live data from both and one heater was open. The combination of all the above made the engine surge at idle and stumble at numerous points of acceleration. I will drop the tank down tomorrow and check the wires and the pressure sensor as I have to install a Draw Tite hitch and will be under there anyway.
