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Thread: Two problems

  1. #1
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    Two problems

    Problem #1 , my water temp guage never would go very high. It would barely go past the first line. The car doesn't get hot and the fans come on at around 160, but the guage never gets to half way to the second line. I decided to ground the sender to see if the guage would move. It did. In fact it pegged really fast. When I took the ground away, my gauge went below zero and has stayed there ever since. I drove the car 500 miles today and the needle never moved. It almost looks like the needle is broke. Is grounding the sender a big no-no on these cars?

    Problem 2 , I installed some LED headlights before the trip. They look great, but now I'm having trouble with the headlight switch not latching. Would that be related to the low current draw? Or is my switch just worn out?

  2. #2
    LS Swapper Josh's Avatar
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    The temperature guage needle can get jammed against the cluster plastic. give the side of the binnacle a bop and it may break free.

    The headlight switch is a fairly common failure item. With the stock incandescent bulbs full current of the circuit flows through the switch. It gets hot and things deform. The latching mechanism is mechanical to the switch not load dependent.

    Supercharged 5.3L LS4 + Porsche 6spd
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  3. #3
    Senior Member Rich's Avatar
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    +1 on Josh's last comment about the HL switch latching mechanism failure.

    The switch latch inside it is very likely just dirty and gummed up, not broken or worn out.

    See posts #2 and #13 in this thread, ignoring references to the bypass relay fix for the high-current issue.

    You can remove the switch, disassemble and clean the its internals to restore the original latching performance. The switch itself is a bit of a puzzle to take apart. You need small pry tools, good lighting at the workbench and some patience. No glue or adjustments/cutting are needed. Pay attention to the orientation of every piece that comes out of it so you can rebuild it correctly the first time.

    Or just buy a replacement switch. Consider selling the old one for parts/repair unless you break it.
    March '81, 5-speed, black interior

  4. #4
    Guru butcher Michael's Avatar
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    If whacking the binnacle doesn't free up the temp gauge, you can fish a small piece of bent wire in through the trip reset hole and dislodge it. It may stick again and for years I kept a large paper clip wire(I think it was) in my ashtray. It wasn't till I fixed a bad ground that the problem went away.
    http://dmctalk.org/image.php?type=sigpic&userid=90&dateline=161808992  9

  5. #5
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    Looks like I got lots of stuff to try. At least the car made a thousand miles in two days. I made it here right before nightfall because I thought I might not get the headlights to come on. It's like one time in ten that it will latch.

    Thanks all.

  6. #6
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    Quote Originally Posted by Helirich View Post
    Looks like I got lots of stuff to try. At least the car made a thousand miles in two days. I made it here right before nightfall because I thought I might not get the headlights to come on. It's like one time in ten that it will latch.

    Thanks all.
    The headlights do have power relays (at least my car does and they're shown on the schematic). In a pinch, you could remove and jumper the "DIP BEAM RELAY 101" and you would have low beam headlights. With the jumper in, the lights are permanently on, bypassing the light panel switch. You would need to remove the jumper to turn them off. The "DIP BEAM RELAY 101" is in the front row of relays. It's the one nearest to the fuse panel.

    Ron

  7. #7
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    If the motor ever overheated it can damage the temp sender or it could just be a dirty electrical connection on the sender or somewhere else. It can also be a little bit of air in the coolant system that needs to be bled out. Sounds like you had a good shakedown cruise and have most of the problems sorted out.
    David Teitelbaum

  8. #8
    Administrator Ron's Avatar
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    Problem #1:
    Since you mentioned the fans come on, note that they are controlled independently from anything involving the temp gauge circuit...

    Problem #2:

    Quote Originally Posted by Josh View Post
    The temperature guage needle can get jammed against the cluster plastic. give the side of the binnacle a bop and it may break free.
    +1

    Quote Originally Posted by Josh View Post
    The headlight switch is a fairly common failure item. With the stock incandescent bulbs full current of the circuit flows through the switch. It gets hot and things deform. The latching mechanism is mechanical to the switch not load dependent.
    Power for the headlights doesn't go through the switch. The main lighting switch feeds the stalk/light switch, which energizes the high or low beam relay...

    ======

    Make sure the switch is not rubbing anything, preventing it from full travel/reset.


    +1, DMC-Ron

  9. #9
    LS Swapper Josh's Avatar
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    Quote Originally Posted by Ron View Post
    Power for the headlights doesn't go through the switch. The main lighting switch feeds the stalk/light switch, which energizes the high or low beam relay...
    True, but the park lights do.

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  10. #10
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    Quote Originally Posted by Josh View Post
    True, but the park lights do.
    Absolutely right! With the old incandescent running lights there's a fair amperage load going thru the main lighting switch. Switching to LED bulbs lowers the current (and heat) at the switch contacts. DeLorean Parts NW sells a light switch relay kit that removes all the direct bulb current from the main lighting switch contacts.
    Ron

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