Testarossa wiring question | FerrariChat

Testarossa wiring question

Discussion in 'Technical Q&A' started by swamthing, Apr 30, 2021.

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  1. swamthing

    swamthing Rookie

    Apr 28, 2021
    12
    Full Name:
    Jonathan Clark
    New to the forum. I just purchases an 89 Testarossa. Trying to figure out a few electrical issues. Dash light fuse blows when I shut the engine cover. Parking lights don't work via the center console button (although it lights up). In any event I was looking at the engine compartment to try and figure out what was going on. I noticed these connectors were not connected with each other. Any ideas what they are? Did someone forget to put back together when they did the engine out service?

    BTW you guys are awesome. Tons of knowledge here.

     

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  2. flash32

    flash32 F1 Veteran

    Aug 22, 2008
    5,561
    Central NJ
    Full Name:
    Dominick
    I would bet your lift supports are making contact with the body

    The Power for lights on bonnet is carried thru the lift support ..and when they touch the body it shorts out the dash lights

    Disconnect the wire on the lifts and see if that helps

    If so look for rub spots

    Sent from my moto g power using Tapatalk
     
  3. flash32

    flash32 F1 Veteran

    Aug 22, 2008
    5,561
    Central NJ
    Full Name:
    Dominick
    I cannot see your pics on my phone so not sure what you are showing

    Sent from my moto g power using Tapatalk
     
  4. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,035
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    #4 Steve Magnusson, Apr 30, 2021
    Last edited: Apr 30, 2021
    +1 -- See this thread for some discussion:

    https://www.ferrarichat.com/forum/threads/dashboard-lights.585340/#post-146224222

    Image Unavailable, Please Login

    We've also had instances of shorted-to-ground ashtray wires in the doors and shorted-to-ground license plate light wires causing fuse #13 to blow IIRC -- but that doesn't apply to you (OP) if you have a direct correlation with closing the engine bonnet = fuse #13 blows.

    Probably intentionally disconnected -- those are for the "Slow Down" Warning Lights and Buzzer. People unplug them when the Warning Light ECU(s) running them go bad (the Warning Light ECUs are mounted on the backside of that metal panel below the 1-6 Accumulator). If unplugged, the self-test will also not work (so is the clue that they've been unplugged, need replacement, and you should pay less for the car ;)).
     
  5. swamthing

    swamthing Rookie

    Apr 28, 2021
    12
    Full Name:
    Jonathan Clark
    Thanks guys I will look for wear on the lifters and check out the license plate. I should have invited all of you to inspect the car!

    Interesting on the ECU. I've plugged them, let's see what happens.
     
  6. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,035
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    Have to think they are turning the warning light(s) "on" at ridiculous/impossible times (like immediately at cold start-up) or in crazy ways (if they are really working, and things are really overheating, they should flash first and then go solid "on" if you keep driving -- so if they just go from "off" to "on solid" = not really how they should work). If they are "dead", there would be no need to unplug them. Having those light(s) "on" is a huge visual distraction, but, if the buzzer hasn't been unplugged, that's even worse ;).
     
  7. swamthing

    swamthing Rookie

    Apr 28, 2021
    12
    Full Name:
    Jonathan Clark
    I found the mark on the passenger side engine lift. I guess that’s why the fuse is shorting out. I’ve put some electrical tape to see if that solves it before I try a more permanent solution.
     
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  8. swamthing

    swamthing Rookie

    Apr 28, 2021
    12
    Full Name:
    Jonathan Clark
    FYI so far only had the "slow down 1-6" show up for 1/2 second while out cruising. I'll report back as I get out and do some driving.
     
  9. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,035
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    Is the self-test at initial key "on" working well on both?
     
  10. swamthing

    swamthing Rookie

    Apr 28, 2021
    12
    Full Name:
    Jonathan Clark
    I’m not familiar with what the self test should do on “on”.
    I’ll do some research
     
  11. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,035
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    It's in the US TR OM under the description of each warning light in Section 1 -- Instruments and controls. The slowdown warning lights should illuminate for a second, or two, when you first turn the key "on", and then they should go out (confirms that the bulb is OK).
     
  12. moysiuan

    moysiuan F1 Rookie
    Silver Subscribed

    Nov 1, 2005
    3,626
    Canada
    Spray some electrical cleaner on the connectors, and trace right back to the slow down ECU's and clean those connectors to the box too. A bit of invisible corrosion can can affect the resistence which is what the heat responsive sensors are actually measuring. The ECU's themselves can fail, but sometimes using a light brass brush to clean the sensor probes in the exhaust system will also solve for things if the electrical connection cleaning does not. Often these things are not addressed because this is all fussy stuff which lends itself to do it yourself labour. I had this warning light intermittent issue when I purchased my car 15 years ago, did the clean up noted and things have worked as they should ever since. I am a big believer in a product called Deoxit as a first step in solving for all electrical related gremlins.
     

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