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328 Electrical Problems

Discussion in 'Technical Q&A' started by msouza, Jan 28, 2006.

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  1. msouza

    msouza Formula Junior

    Mar 14, 2005
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    Milton Souza
    #1 msouza, Jan 28, 2006
    All the dash lights on my 328 are not working, the instrument cluster (speedo/tach) and at the 3 gauges on the center of the dash. Everything else works normally. While investigating the source of the problem, I found the 8th fuse (15A) counting from the left to be blown. I replaced the fuse, but as soon as I turn the headlights on, it blows again.

    Looking at the wiring diagram for the 328, I pulled relay ‘O’ out and check for continuity between pin #30 (constant 12V) and the top most pin. Well, I did find continuity between these two pins, which leads me to believe I have a short somewhere. If I am reading the wiring diagram correctly, the top most pin is ground, and I should not had continuity there.

    Now I am lost, don’t know where to go from here. Help please.

    Regards,

    Milton
     
  2. radioman

    radioman Karting
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    #2 radioman, Jan 28, 2006
    pin #30 on the relay 'O' is the main feed in it should be live all the time it is fed off the bus 'B'. if the fuse blows when the lights are switched on then you may have a short in the light circuit. check the yellow striped red wire which comes out of the fuse panel in connector 'J', position '3' ,i think, at the top of panel. measure with a ohm meter after unplugging the connector 'J' between it and ground and see what you get. (discconect the battery first)
    this circuit is the side light circuit. the circuit that switches on the head lights and lifts them is quite complicated so this might take some time, checking out the simple stuff first we can cross it off the list. chris.
     
  3. msouza

    msouza Formula Junior

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    Milton Souza
    #3 msouza, Jan 28, 2006
    Thanks Chris, I'll check that out as soon as I get back home today. But, after reading your post, I think I am checking the continuity beetwen pin 30 and the top most pin the wrong way, I didn't disconect the battery. Please correct me, if I'm doing this the wrong way.

    Regards.

    Milton
     
  4. msouza

    msouza Formula Junior

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    #4 msouza, Jan 28, 2006
    Chris, just measured the resistance between the 3rd terminal on connector J (yellow with red stripe wire) and ground, it reads 0.4 ohms.

    Correct me if I am wrong, but this shows a short in the circuit.

    Milton
     
  5. DGS

    DGS Seven Time F1 World Champ
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    #5 DGS, Jan 28, 2006
    Not necessarily. That wire feeds all of your parking lights, in parallel.

    At 12v a static 0.4 ohms would indicate 30A ... but high current circuits are tricky, as loads vary when things heat up.

    Your next move might be to check your parking and side marker bulbs and sockets.

    If I can read that wiring diagram with aging eyes, I'll see if there's something else obvious to try. (Unfortunately, the movers trashed my desk lamp.)
     
  6. radioman

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    #6 radioman, Jan 29, 2006
    your answer is correct, now that we have established that you know what you are doing we will try to find your problem.

    the measurment that you made was the switched feed to the lights so it should read almost a dead short because when you applied the meter probe to the wire then the meter would have measured through the lamp to ground thus showing an almost dead short, except for the very small resistnce of the lamp. when a meter measures resistance it brings into play the battery inside the meter putting a voltage into the circuit you are measuring this is why you need to disconect the car battery to get the correct reading and in some instances to stop blowing up the meter. ok i will try not to digress anymore.


    ok disconnect plug 'j' replace the fuse 15 (8th from the left) switch on ign and switch onside lights if the fuse blows then the problem is local if it dosnt blow then we have to look 1, behind the dash 2, at the external lights.
     
  7. msouza

    msouza Formula Junior

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    Milton Souza
    #7 msouza, Jan 29, 2006
    Hi Chris and DGS, thank for your help.

    I have determined that the fuse blows when I rotate the stalk at the steering column to the parking light on position. Now going back to Chris instructions:

    Plug “J” disconnected.
    Battery re-connected.
    New fuse 15 installed on #8 position.
    Ignition switch on.

    When I turned the lights on, the fuse DID NOT blow. I tried with just the parking lights, and also raising the headlights.

    I will be back home in a couple of hours, then I’ll look at all the side markers and parking light sockets like DGS suggested.

    Regards,

    Milton
     
  8. msouza

    msouza Formula Junior

    Mar 14, 2005
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    Milton Souza
    #8 msouza, Jan 29, 2006
    Well folks, thank you so much for all your help.

    Problem is solved. Before going to church, I decided to take a quick look at the light sockets, the first one I looked at, was responsible for all my troubles. The rear driver side parking light. Two wires were striped and grounding to the harness.

    After fixing the grounded wires, I tested the dash lights, and everything is working in perfect order. No more blown fuses, so far.....

    Once again, thank you very much for all the help. You guys were great.

    Regards,

    Milton
     
  9. radioman

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    #9 radioman, Jan 29, 2006
    glad you found it! chris.
     

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