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Circuit Opening Relay Location???

Discussion in '1st Gen. Tacomas (1995-2004)' started by iveywt, Oct 25, 2014.

  1. Oct 25, 2014 at 4:38 PM
    #1
    iveywt

    iveywt [OP] New Member

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    Super Charger K&N Intake
    So I am wondering if all 2001 Tacoma models have a Circuit Opening Relay. My truck cranks and will start for about 1-3 seconds then dies immediately. I have changed fuel pump, spark plugs, coil packs, heated oxygen sensor and A/F ratio sensor, all vacuum hoses, and the fuel filter. Before I replace the ECU I was trying to check the Circuit Opening Relay but it is not located where the service manual says it should be. I have spent a large amount of time looking for it but cannot locate it.

    I bought my truck with the supercharger already installed I was wondering if for some reason the Circuit Opening Relay has been removed or if maybe all models/packages did not come with the relay.

    If anyone has a 2001 Toyota Truck Tacoma Extra Cab 4WD V6-3.4L (5VZ-FE) and could you take a picture of the relay and the location it would be greatly appreciated because I have exhausted the internet looking for it.

    I should add that this problem happens intermittingly; it will always fire and start and then just dies like the fuel has been cut off immediately sometimes it will not start at all, then I can leave it alone for an hour then come back and try it and it will start first try.

    The code that it throws is P0171 system running lean. But this code would be correct it the fuel is being cutoff.
     
  2. Oct 9, 2015 at 6:17 PM
    #2
    fire03capt

    fire03capt New Member

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    Hello, Did you ever find the location of your circuit open relay?
     
  3. Oct 9, 2015 at 11:36 PM
    #3
    Caligula

    Caligula It's the COVFEFE

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    Thread is a year old. Low chance he is still staring at a Tacoma that wont start.

    For reference, the relay is above where your left knee is when you sit in the truck. Its attached to the support tube for the dash structure, directly below the instrument cluster. It has a green casing.
     
    SteveW504 and tacopashka like this.
  4. Oct 21, 2015 at 8:04 PM
    #4
    fire03capt

    fire03capt New Member

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    I have looked and looked in that area as well as everywhere under the dash and there is no circuit open relay there.
     
  5. Oct 21, 2015 at 8:15 PM
    #5
    Madjik_Man

    Madjik_Man The Rembrandt of Rattle Can

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    Mine is exactly in the place as he describes. 99% sure it's in the same location for your 2001.

    photo2-13_zps00a668e2_8607ee420b07605c5208433aefd20bb98c832ec1.jpg
     
  6. Apr 8, 2016 at 6:31 PM
    #6
    RIPSAW 2

    RIPSAW 2 Member

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    HAMPTON ROADS VIRGINIA
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    TAC DASH, VARIABLE WIPER SWITCH,LARGE ELECTRIC MIRRORS, SPRAY BED LINER
    Since this is a close match to my problem and need of understanding..Will present my thought and hope others can do some enlightenment.

    Truck only has 50K bought new by me. First problem ever. Will start up but dies when you come off start side of key. Slightly different setup from yours. 2004 4x4 Regular Cab Tacoma with the 3RZ-FE has the circuit opening relay under the drivers side fuse box and not like Madjik's above but close and the wire colors are the same. The relay is the same part number as the EFI relay and power supply in fuse box 2 under the hood. Relay is single control with only one coil. EFI relay supplies power to Circuit opening relay. The start side of the ignition supplies the control side of the circuit opening relay and the ground side of this control is the ECM.

    So in a nut shell, the circuit opening relay closes and turns on the fuel pump when cranking. When motor starts, when you let off on the start, the running condition then makes the relay stay closed and keeps fuel pump on. If by chance, motor does not continue running, the normal on side of the ignition key does not keep relay on and the fuel pump does not run. (it's a safety switch to the EFI relay) Other cars use a timer to to run pump and do not have this extra relay. The running part that tells the ECM to keep the circuit opening relay closed is the Cam Position sensor.



    Problem comes and goes. Driving me crazy and can no longer trust truck. Truck still has a airflow valve. Fuel pump pumps fine when you give it power to the blue wire on the circuit open relay. The call out for the fuel pump is .2-3 ohms . It reads 1.3 at the wire at the relay. Crank sensor calls for 1630-2740 ohms. It reads 2060. Pain to get to the camshaft sensor under the intake, so not checked.

    This system does not have a fuel pump timer like most FI engines?

    Another interesting fact is this motor has two 3 temperature sensor. One back by the ERG valve. One on the front right water housing (controls temperature gage) and the important one is hidden in back of motor on back side of valve cover at firewall. (need to lift protected wire harness on three hangers to see it). It is what reports to ECM for start and warm up fuel mixture.
     
    Last edited: Apr 10, 2016
    tacoma_ca likes this.
  7. Sep 4, 2016 at 2:40 PM
    #7
    vinnier

    vinnier New Member

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    I am having the same problem as iveywt in regards to finding the Circuit Opening Relay. I cannot find the COR on my 2002 Tacoma 3.4L. Every resource I have (Haynes, FSM, internet, friends, etc.) all point to or suggest the relay is near the drivers left knee. There are other relays, but I don't see the COR. I am going based on what I have understood the relay to look like. I have attached a few pictures showing the COR from RockAuto and what I am seeing under the dash. I have been staring at this for way too long...

    On a second note, I am suggesting this may be the problem of fuel not pumping through the fuel system when I turn the ignition to the ON position. I have exhausted many other options.

    Picture2.jpg
    Picture1.jpg
    2016-09-04 14.11.10.jpg
    2016-09-04 14.11.04.jpg
    COR.jpg
     
  8. Sep 5, 2016 at 9:37 PM
    #8
    License2Ill

    License2Ill Woke like a Coma Toyota Tacoma

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    It's a dry heat thou, AZ
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    Bailing wire & Duct tape

    The COR for an 02 5vz, is located on the back of the body relay fuse box(J/B No.1 #11 PWR Relay). Second picture, left-most red outline. p/n 90084-98031
     
  9. Sep 5, 2016 at 11:01 PM
    #9
    vinnier

    vinnier New Member

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    Thanks License2Ill for the response. I was doing some further digging today in the FSM and comparing to what I am seeing in the truck and have convinced myself the COR is the one in the 1st picture of my original post with the red square around it (don't mind the silver markings). Looking at the below circuit in the FSM, I was able to compare the wire connections to the harness in the truck. This along with various other clues in the FSM, such as testing procedures, pointed me to this relay. The Power Relay you mention is to the left of the COR, but it looks to be the same type of relay, so they are most likely interchangeable.

    To address the no-start issue, I was able to get it solved, well at least the truck started. The actual cause is still undetermined. I'm thinking it had to do with a short somewhere between the battery and the ignition switch because I had been checking the fuses throughout the troubleshooting process and they all were fine, until I got to the step of checking the EFI fuse(again) while troubleshooting the ECM. If I end up finding something more solid in the future, I'll make sure to update this post.

    Picture1.png
    Picture1.png
    Picture2.jpg
     

    Attached Files:

    Last edited: Sep 6, 2016
  10. Sep 6, 2016 at 6:31 PM
    #10
    License2Ill

    License2Ill Woke like a Coma Toyota Tacoma

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    Bailing wire & Duct tape
    Interesting. 2003's and 04's have that fuse in the location I had identified. I ripped apart my 04 donor truck to the point I have all nuts and bolts from the complete truck in a bucket. Only random fuse I encountered was the transmission relay floating under the glove-box.
     
  11. Sep 6, 2016 at 10:10 PM
    #11
    vinnier

    vinnier New Member

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    I agree. Very odd. I was stumped on this for much longer than I'd like to admit. Hopefully this helps anyone out there with the same truck as mine.

    I updated my previous post. I had the wrong location of the COR called out in the 2nd image. Correct words, just incorrect yellow square location.
     
  12. Sep 12, 2016 at 1:55 PM
    #12
    RIPSAW 2

    RIPSAW 2 Member

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    TAC DASH, VARIABLE WIPER SWITCH,LARGE ELECTRIC MIRRORS, SPRAY BED LINER
    On trucks before 04, is to right of cap fuse bock on the structure near the left side of the steering column. The other is located in the fuse box under hood near battery.

    I have not researched the V6 has this system. Sure it does not have a timer circuit like most modern car have with only one fuel pump relay?
     
  13. Sep 12, 2016 at 2:14 PM
    #13
    vinnier

    vinnier New Member

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    I don't believe the '02 v6 has the timing circuit.
     

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