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FAST EZ-EFI 2.0 Fan controls???

Discussion in 'FAST Support Forum' started by silvernblack, May 18, 2018.

  1. silvernblack

    silvernblack Member

    Joined:
    Dec 18, 2011
    I had a voltage dip to about 11 vdc today. Thereafter my radiator fan quit working and I did not notice as I drove around town. Once I got on the highway - then I noticed the engine temp at 255°F! Yowzy!! I slowed down to about 55-60 (~1850 rpm in OD) and the temp slowly trended down and stabilized at about 200°F so drove the ~20 miles home.
    I was suspecting the suspecting the fan since once I was cruising at low rpm and 60 mph the temp just trended down.

    I got home (my only purpose at that point) and verified that the Mark-8 fan was not functioning. I put the car away to let it cool off to come back later.

    I later came back and verified that the fan works when 12 vdc are applied directly. As I was troubleshooting I also remembered that I had installed an "override" switch as I looked around the passenger side under the dash (yeah- it worked promptly energizing the actuating fan relay immediately--I coulda used it if I remembered :)).

    Anyway- it appears that I am not getting a "full" voltage signal from the ECM to actuate the fan relay...so it does not PICK-UP when required. I don't think I ruined the FAST EZ-EFI 2.0 because the engine ran like a dream-- even when it was at 255°F. And yes, it was really 255°F, from the EZ-EFI indicator and my separate and independent dash gauge.... Any pointers before I tear everything apart?
     
  2. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    It would be a good idea to save all your settings and do a Wizard reset several times - then inputting all your settings. The fan sensor should then see your fan and allow you to set its temp. If the fan circuit isn't completed correctly, the ECU won't turn either fan circuit on until it can see a completed circuit connected to one or both. If you only use one fan, the ECU will only turn on the connected fan circuit.
     
  3. silvernblack

    silvernblack Member

    Joined:
    Dec 18, 2011
    Thanks. I did one reset and it didn't seem to do anything. I'm beginning to suspect it's a different issue. The electric radiator fan will not start on the A/C demand either so I'm going to have to check the wiring interface between the EZ-EFI 2.0 and the A/C controls. Something is a bit odd because the the fans starts just find with the manual bypass switch. Thanks.
     
  4. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    Just an added note - the ECU fan wires are only for use with relays powering the fans. Using them without relays will damage the ECU and require an RMA of the ECU for repair.

    Even if this didn't happen, your ECU needs an RMA for warranty repair.
     
  5. silvernblack

    silvernblack Member

    Joined:
    Dec 18, 2011
    I've had it for about 5 years. It is being used with relays.
     
  6. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    Yep, you need to contact FAST Tech and get a RMA number for repair. The repair is covered under your limited lifetime warranty.
     
  7. silvernblack

    silvernblack Member

    Joined:
    Dec 18, 2011
    Is there a way to troubleshoot whether the ECM is receiving/processing the HI-TEMP signal? I gather that I could simulate the high temp at the sensor and see if the ECM creates a ground demand....hmmmm....
     
  8. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    Just look at the temp displayed on the handheld Master screen. If the handheld is displaying the correct temp, the ECU is also being supplied the same temp signal. (The handheld sees what the ECU sees.)
     
    Last edited: Jun 24, 2018
  9. silvernblack

    silvernblack Member

    Joined:
    Dec 18, 2011
    Just sharing because I don't know what the heck happened.

    I went to troubleshoot the temperature sender for the Mark-8 Radiator Fan failure to start. I hooked up the battery, turned the key to "ON", and then disconnected the connector at the temp sender.... well, holy cow, the fan started! SO, I plugged it back in and did it again. Fan started as soon as I disconnected it. Hmmmm.... so, I actually ran the handheld to the engine compartment and did the connect/disconnect again as I monitored temperature on the handheld. Sure enough - the fan started and stopped as I disconnected and reconnected.... temp reading was something odd like -2 or +2 when connector was disconnected.

    SO, next I removed the sender and simulated a high temperature (using my little soldering torch) as I monitored temperature on the handheld. Sure enough, fan started at 180°F and stopped at 175°F per the setpoints installed.

    THEN, I hooked up my spare Temp Sender and did the same test. Tested sat again.

    It looks like it's all working well ... I suspect something oddballish with connecting/disconnecting the leads at the temp sender. I will put it all back together and see how it works.
     
  10. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    Sounds like some of the wiring at the fan relay is incorrect or you have an intermittent short. Your fan relay may have NC and NO contacts or some other problem.
     
  11. LnL

    LnL Member

    Joined:
    Nov 24, 2010
    "Anyway- it appears that I am not getting a "full" voltage signal from the ECM to actuate the fan relay." How do you have your relays wired? The FAST ecm - on the systems I've installed - provides the GROUND to the fan control relays.
     

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