eviper21 Posted December 14, 2009 Report Share Posted December 14, 2009 when its off the car i cant read the .9 volts its supposed to read while its on the car so ima take it off and inspect it....its probably bad like all the other isc servos out there my idle doesnt raise when its cold Link to comment Share on other sites More sharing options...
mikec Posted December 14, 2009 Report Share Posted December 14, 2009 ISC test procedure:You'll need a good ohmmeter (digital or analog, analog is easier to see/use), 4 "AA" batteries in a plastic holder. Do NOT use a car battery, NiCad batteries, etc... just plain old cheapie "AA" batteries. Why? Because "AA" batteries can't deliver too much current; other batteries can deliver enough current to damage the ISC motor when the motor reaches the limits of its travel. Unplug the ISC connectors. One is the ISC "motor" connector; two of the three wires will go to the motor body (the part encased in a black protected cover); the 3rd wire is the "idle switch" wire. The other connector wires will go "into the mechanism someplace" - this is the "Motor Position Sensor" (MPS) connector. Hook the ohmmeter to any 2 of the MPS connector pins. Hook the "AA" battery pack to the ISC motor wires. The whole assembly should whirr/buzz a little; the rubber bellows pointing downwards should either extend or retract. Once it stops moving, reverse the polarity of the battery pack and watch it move the other direction. The total motion is about half an inch if I remember correctly. The motion should be smooth - no hesitation, no jerkyness, no funny sounds. If the ISC motor extends/retracts okay, now check the MPS. Re-connect the battery pack and as the ISC extends or retracts watch the resistance. It should change smoothly and in sync with the extension/retraction position. If the resistance stays constant, move one ohmmeter wire to a different connector pin and re-test: your initial connection happened to be across the "ends" of the MPS sensor, rather than to one end plus the "wiper" output pin. Once you verify the MPS resistance in in sync with the motor position, test the idle switch (aka "nose switch"): Connect the ohmmeter to the 3rd wire of the ISC "motor" connector and to the body of the assembly. On the end of the rubber bellows you'll see a small metal "button" switch. Push it gently with a fingertip. The ohmmeter should read zero ohms; or no more than a couple tenths of an ohm. Now release the switch. The resistance should instantly change to infinite ohms (open circuit). Repeat a few times, making sure the swithc is reliable. Now connect the battery pack and run the ISC motor for half a second... retest the nose switch. Test the nose switch at several ISC extension positions - covering the full stop-to-stop range. mike c. Link to comment Share on other sites More sharing options...
eviper21 Posted December 14, 2009 Author Report Share Posted December 14, 2009 will a 9v battery work for this test Link to comment Share on other sites More sharing options...
mikec Posted December 15, 2009 Report Share Posted December 15, 2009 Don't use a 9 volt battery. I doubt a 9 volt battery will be able to deliver enough current (amps) to actually fry the motor wiring but:* with 9 volts there will be plenty of excess "oomph" from the motor to overcome any binding/sticking in the gearbox. This will mask a borderline gearbox. The ECU sends a much lower voltage signal to run the motor normally - just a few volts. * The part that extends/retracts does so via a screw moving in/out. When the ISC mechanism is at the physical end of its travel, it is pushing on a fragile washer-like piece. That thing is easy to bend/deform which then jams the ISC. Hitting the ISC motor with a voltage higher than it was designed for, or hitting it with only 5 to 6 volts from something that can supply high amperage can lead to damaging this washer. That's why I tell folks to use plain/cheap "AA" batteries: they can't deliver much current even when the ISC motor is "stalled" against the physical travel limits. NiCads, lithium ion batteries, possibly even alkaline batteries, might be able to supply enough current to make the ISC motor run excessively fast and "slam" into the physical stop, damaging that washer. Using more than 6 volts will likely make the ISC run too fast. mike c. Link to comment Share on other sites More sharing options...
jettajody Posted December 15, 2009 Report Share Posted December 15, 2009 Don't use a 9 volt battery. I doubt a 9 volt battery will be able to deliver enough current (amps) to actually fry the motor wiring but:* with 9 volts there will be plenty of excess "oomph" from the motor to overcome any binding/sticking in the gearbox. This will mask a borderline gearbox. The ECU sends a much lower voltage signal to run the motor normally - just a few volts. * The part that extends/retracts does so via a screw moving in/out. When the ISC mechanism is at the physical end of its travel, it is pushing on a fragile washer-like piece. That thing is easy to bend/deform which then jams the ISC. Hitting the ISC motor with a voltage higher than it was designed for, or hitting it with only 5 to 6 volts from something that can supply high amperage can lead to damaging this washer. That's why I tell folks to use plain/cheap "AA" batteries: they can't deliver much current even when the ISC motor is "stalled" against the physical travel limits. NiCads, lithium ion batteries, possibly even alkaline batteries, might be able to supply enough current to make the ISC motor run excessively fast and "slam" into the physical stop, damaging that washer. Using more than 6 volts will likely make the ISC run too fast. mike c.So what do you do when that washer becomes completly trash?????????????? Link to comment Share on other sites More sharing options...
eviper21 Posted December 15, 2009 Author Report Share Posted December 15, 2009 i just found out that my manifold isnt grounded... i dont have the little plug/I-bolt to ground it so i think ima make one.. could that be why my isc isnt working?? i would think it would draw ground from somewhere no? the throttle cable anything. Link to comment Share on other sites More sharing options...
mikec Posted December 16, 2009 Report Share Posted December 16, 2009 Only the nose switch uses the manifold ground. The ISC motor wires both go to the ECU, as do all wires from the MPS. The engine block should be grounded via the beefy black cable from the battery to the body to the engine block. Often this cable corrodes/rots, and/or the spot on the block is painted over when an engine is rebuilt. That grounding pad needs to be cleaned of paint when an engine is re-installed. The intake manifold, exhaust manifold, and injection mixer assembly should have paths to ground via their mounting bolts/studs even though they might be "isolated" otherwise via gaskets. Still, Mitsu ran dedicated ground wires to the intake manifold to make sure. mike c. Link to comment Share on other sites More sharing options...
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