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Electrical Help Needed


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15 replies to this topic

#1 ocei77

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Posted 27 July 2011 - 09:19 PM

1997 Legacy with 2.2L Auto

Problem: getting code P0443: Purge control Solenoid Circuit Low Voltage Input.

Have my own scanner. Tried replacing from a salvage car . Still got code.

Called dealer to just order unit. $179!!!!
No way. Still trying salvage route, but what I need if someone can give me the voltage from a properly operating unit. Maybe I can trick the circuit to get rid of this code and the CEL that goes with it.

I have wiring diagram, but don't know the expected voltage.

Thx.

O.

#2 GeneralDisorder

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Posted 28 July 2011 - 01:36 AM

Wire in a 33 Ohm, 5 watt resistor in place of the solenoid. Or any junk yard solenoid that tests to about 30 to 40 ohms.

GD

#3 bstone

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Posted 28 July 2011 - 11:15 AM

It might mean that there is a wire problem. The wires might be frayed or cut, leading to low voltage. I JUST had this with the Engine Coolant Temp Sensor. Ended up doing a fair bit of splicing. Sensor itself was just fine.

#4 ocei77

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Posted 28 July 2011 - 05:30 PM

Thanks for info, will do Radio Shack tomorrow.
Meanwhile I'll look for bad wires.

O.

#5 Cougar

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Posted 28 July 2011 - 06:19 PM

The solenoid should have 12 volts getting to it when it is supposed to be activated. Either the wiring to the solenoid has a problem or the solenoid coil is open. Since you tired a replacement already it most like means there is a problem with the wiring to the solenoid.

#6 GeneralDisorder

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Posted 28 July 2011 - 09:15 PM

That solenoid is a pretty common failure though - the salvage one he got could be bad also. DMM would tell you in an instant.....

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#7 Fairtax4me

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Posted 28 July 2011 - 10:21 PM

Connect the two green plugs under the dash and turn the key to ON to put the ECM in test mode. See if the solenoid clicks every half second. Check the connector for a 12 volt pulse while in test mode.

A likely place to check for wiring issue or poor connection is the large junction blocks on the passenger side of the bell housing. They often get dirt/corrosion on the pins inside the connectors and can cause some big problems.

#8 ocei77

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Posted 30 July 2011 - 08:43 PM

Update: Still fighting with this.
Radio Shack didn't have a 33 ohm unit in stock, took a 47 until the right one was available. Worked for 18 miles then got code again plus 1102 Purge Solenoid Malfunction.
Went to salvage yard and got another unit, the cleanest I could find. Code returned in 2 miles.
Connected test plugs. I get the clicking of the solenoid.
Tried an EGR solenoid also, Very close to same but ports in different locations. No Good.
Tested resistance on the three Purge and the two EGR solenoids I have. All are 13 ohms.
Wires are good all the way.
Next is the sensor that attaches to the purge unit.
Hope to just loosen the canister connections and reattach, just for the hell of it.
Sprayed soapy water on all the vacuum lines. No leaks.
Hope to find a 33 ohm unit on Monday.
Meanwhile any and all suggestions are welcome.

Thx.

O.

#9 GeneralDisorder

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Posted 30 July 2011 - 09:12 PM

13 Ohms eh? That's pretty strange - check your meter against the 47 Ohm resistor you bought.....

GD

#10 johnceggleston

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Posted 31 July 2011 - 08:21 AM

seems like you have all this info but just in case.

http://www.obd-codes.com/p0443

#11 ocei77

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Posted 31 July 2011 - 03:41 PM

13 Ohms eh? That's pretty strange - check your meter against the 47 Ohm resistor you bought.....

GD


Checked, couldn't get reading. Off scale. Have an old analog unit.
Just went out and purchased a digital. Older solenoid units read 40 and 41 ohms.
Another question, (can't remember my old electronics) if 33 ohm unit still not available. Can I put in series two 15's to get 30?

Thx,

O.

#12 Cougar

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Posted 31 July 2011 - 05:25 PM

You are correct in your thinking, resistances values simply add together when in series. The older solenoid values should work also in the circuit.

#13 ocei77

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Posted 01 August 2011 - 07:32 PM

Update 2

Checked wiring as far as I could. Continuity is there.
Plugged in test connectors again. Solenoid clicks and I get voltage of 11.89 when circuit activates and 3.87 when idle, which seems high according to the info I have. (should be near 1 or less)
All now leads to a possible bad driver circuit from ECM.
Any other ideas?

O.

#14 GeneralDisorder

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Posted 01 August 2011 - 08:23 PM

Hhhmmm - typically the solenoid is given a constant 12v and then the ECM controls the ground signal to the solenoid.

If you choose to use a resistor in place of the actual solenoid - you can wire it in at the ECU instead of in the engine bay.

It would be VERY rare to have an ECU failure of the driver circuit. It could happen but I've never seen it. I've seen a solenoid driver circuit burn out a transistor on a TCU but never an ECU. They are very, very reliable.

GD

#15 Cougar

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Posted 02 August 2011 - 12:15 AM

Going from your test readings the circuit is working like it should be. You should see close to 12 volts going to the solenoid when it is on, just like you did. The open circuit voltage reading is not a real concern, it is what it is. The error code seems to be due to a fault inside the ECU.

#16 Fairtax4me

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Posted 02 August 2011 - 12:33 AM

Update 2

Checked wiring as far as I could. Continuity is there.
Plugged in test connectors again. Solenoid clicks and I get voltage of 11.89 when circuit activates and 3.87 when idle, which seems high according to the info I have. (should be near 1 or less)
All now leads to a possible bad driver circuit from ECM.
Any other ideas?

O.


Try checking the voltage again at the ECU connector. I could tell you which pin(s) to tap into but I don't have quick access to the FSM right now.




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