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bypassing a solenoid-replacing with an equal load

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Newbie level 3
Dec 8, 2005
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Hi all,

I have a couple of emissions solenoids on my car that i would like to bypass. I can unplug them, but then i get a check engine light.

I've gotten suggestions to replace the solenoid with an "equal load", but i don't have a clue as to what i should do.

If it helps any, the solenoids have two prongs, and each solenoid has a 100ohm resistance.

Again, I have no idea where to start with this task.

i can post pictures of them if that would help

-thank you all in advance for your help

At 12 volts a 100ohm purely resistive load will draw about 120ma's of current. This means you'll need at least a 2 watt 100ohm resistor to replace the solenoid. For saftey's sake you may want to use a higher wattage to prevent over heating. Solednoids do work, resistors just generate heat, and you don't want a fire. Be safe.

sounds good...

i posted in another forum and others suggested the same thing. I found a 100ohm 10w resistor that people said would be fine.

just of would this work? does the resistor just simulate a load or does it serve another purpose?

i attached a couple of pics of what these solenoids look like.

thanks again for helping.

It doesn't simulate a load... it IS one. The only difference between a 100ohm solenoid and a 100ohm resistor is the solenoid actually does some work, the resistor just heats up. Basically your car has some kind open circuit detector on the solenoid lines. You might be able to get away with using a much higher value resistance to reduce the power/heat generated by the resistor but this would require trial and error. If it's something as trivial as a voltage detector you could probably use a 1/4 watt 1meg resistor instead. It would waste no power and should still fool the open circuit detector of the car computer. I'd try it, would if nothing else reduce the amount of heat you're generating. It would also be MUCH smaller.

could i try this with a 10meg 1/4 watt resistor as opposed to a 1meg one?

I think the control circuit detects if there's a current through the solenoid to see if it's working or not.
You can simulate it using a 100 ohm resistor,but if I were you,I would try using higher values.
It depends on the threshold.Try with different values to see how high the resistance can be without setting the alarm.
If you manage to do the trick with a 200 ohm resistor (for example),you will have less problems with heat dissipation.
I personally doubt if 1Mohm will do the job.The control circuit shouldn't be so easy to outsmart :)

10meg might be too high, but go ahead and try it, it'll either work or not, I'd try a 1meg next, and then if that doesn't work try adding more 1meg's in parrallel. 2 1 meggers in parrallel will give you 500k, three will give you 333k four would be 250k etc.. If you get down to 250k and it's still not doing anything batdin is probably right and the sensor is detecting the current, in which case you'd have to slowly add more resistance starting at 100ohms till you found the threshold of the sensor and then back it off a bit. Or if you're okay with it, just use the high power 100ohm resistor.

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