no instrument lights

Discussion in 'Troubleshooting & Diagnosis' started by cordero51, Jul 16, 2020.

  1. cordero51

    cordero51 Member

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    i replaced the fuse, the headlight switch as well, and checked for corrosion the bulbs, replacing them with new ones and add another ground from the instrument cluster. and still can't get the gauge lights to light up. i do have the turn signals and high beam indicator as well as the seatbelt notification. I believe the grey wire from the cluster is lights? should I trace the wire and look for any kinks I'm lost right now, any advice would be appreciated.
     
  2. Twisted_Metal

    Twisted_Metal Administrator Staff Member Lifetime Gold Member

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    Yes, it’s the grey wire.

    I’ll assume you have rotated the headlight knob.

    Check for power at both sides of the small fuse. (With the headlight knob pulled.)

    If you have power on both sides of the fuse check for power at the connection for the grey wire at the Cluster plug.

    If you have power there, the problem is in the cluster.

    Does the light work for the heater control or wiper switch?
    (That is powered by the grey wire from the headlight switch too.)
     
  3. cordero51

    cordero51 Member

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    no, the lights don't work for the wiper switch and heater control, I used the continuity tool to check at the fuse box and two of the fuse slots had no power at all. I highlighted them both in red. could this be the problem as I'm not sure to what they belong to as the labeling has been removed. and how would i go about getting power to the actual fuse. thanks
     

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  4. Twisted_Metal

    Twisted_Metal Administrator Staff Member Lifetime Gold Member

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    Is that an 80 or 81 fuse block?

    (I can tell by the blade style fuses it’s one of those years.)

    When I know which year it is... I’ll check my Haynes manual diagrams.

    I also have a pic of an 80 fuse block which still has the labels.
     
  5. cordero51

    cordero51 Member

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    yes its a 1980, are the two fuses that are not receiving power responsible for the issue?
     
  6. Camaro Tim01

    Camaro Tim01 Veteran Member

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    the gray wire hanging down unplugged.... did you unplug that from one of the terminals you have circled in red ?
    How did you test that terminal exactly ?
    continuity test isnt the way
    should be a voltmeter set on 12V to read the voltage, not set on ohms to read continuity
    pull out one fuse at a time, put your meter leads across the blades while the meter IS on OHMS and see if the blades are connected inside, Any that arent are blown and need changing....
    now turn meter to 12V DC place the negative lead on a good ground and touch the red to one side of the fuse terminal see if you read 12V, ONE side of the two terminals where the fuse plugs in should show 12V....

    the smaller red circle in your pic gets its power from the 25amp fuse directly beside, thats the fuse you want to verify if you have trouble with that terminal...

    https://nastyz28.com/camaro/wire/1978-camaro-instrument-wiring.html
    https://nastyz28.com/camaro/wire/1978-camaro-instrument-wiring.html

    Did you perform the test Twisted suggested ?
    "If you have power on both sides of the fuse check for power at the connection for the grey wire at the Cluster plug."
    ????

    plug the gray wire back into fuseblock, disconnect plug to cluster, turn all lights on ( pull knob out) , put meter on 12V DC , black lead on a good ground, red lead on the gray wire of connector ( should be the 2nd from one of the ends )
    Do you have 12V there ?



    all that aside, my money is on the resistor coil that controls the dimmer in your headlight switch....
     
    Last edited: Jul 18, 2020
  7. Twisted_Metal

    Twisted_Metal Administrator Staff Member Lifetime Gold Member

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    The upper fuse (5 Amp) is for your instrument lights.(INST LMPS)

    You need to pull the headlight switch out to either position for it to get power.
    (AND make sure the headlight knob is rotated counter-clockwise.)

    The lower circled connection is also powered off the upper 5 amp fuse.
    Mine has no connection there.
    (l believe that would be used as the lighting circuit for additional gauges.)

    Here's a pic of an 80 Fuse block with fairly legible labels.
    upload_2020-7-17_23-23-36.png

    Does your car have power windows and/or locks?
    Your 20 Amp fuse (silver rectangular thing on the left) looks like a circuit breaker rather than a fuse.
     

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  8. cordero51

    cordero51 Member

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    the car does not come equipped with power windows but it does have power locks, and the grey wire unplugged was plugged in originally in the 2nd red circle next to the 25 amp fuse I just had it unplugged because I used the continuity tool there and the bulb did not light up at all compared to every other fuse terminal. I did have the headlight switch pulled out so the headlights were running. and no I wasn't able to do the test that twisted suggested because the light wasn't going off at the fuse so i assumed i wasn't getting power at all but I don't have a voltmeter yet. I'll go buy one tomorrow and let you guys know the results. thanks for suggestions btw
     
  9. Camaro Tim01

    Camaro Tim01 Veteran Member

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    its your dash lights not working right ?
    according to Twisted pic, that's the INST LPS ( stands for INSTrument LamPS) fuse at the top left beside the flasher relay
    take out that fuse and test for power

    In his pic there is also another labeled LPS with a little arrow beside it, test this also for power, that should be where your gray wire plugs into
    [​IMG]

    ** now that 2nd fuse I said to test shouldn't be connected to your lights but because your gray wire plugs in right beside it and there's a difference between the diagram and the pic on locations, test it for power anyway to make sure it doesnt supply power to the grey wire ( it really, really shouldn't be )... I'm thinking inside the fuse block is a copper strip that runs downward and your INST LPS fuse also feeds your LPS plug terminal....

    https://nastyz28.com/camaro/wire/1978-camaro-dashcolumn-wiring.html

    in that diagram wire is circuit #8 ( 20 GRY ) going from cluster connector to fuse block and plugging into #44 which is connected through your INST LPS fuse ( #8 )
    https://nastyz28.com/camaro/wire/1978-camaro-dashcolumn-wiring.html

    So the diagram on this site and the pic Twisted posted are slightly different but the wiring WONT change, the location of the fuse in the fuse block might but basically you need power going from fuseblock to headlight switch then to cluster...
    makes sense right ? get power, give it to switch to turn things on and off, then connect it to lights....( not exact description of how it that circuit works but gives you an understanding )

    READING WIRING DIAGRAMS
    people are afraid of wiring and the diagrams that come with them, dunno why, they just are... theyre actually very simple to follow, you need good eye site or a magnifying glass but other than that, easy peasy....

    Three things to know to read a diagram

    1. you have a circuit number, this is usually found in the fuse block or on the connector yours for example can be found at the fuseblock and is #8

    2. you have a wire gauge , this is the number in the line you are following in the diagram yours for example is 20 ( its also the thickness of the wire in that circuit ie: 20 gauge )

    3. you have a wire color, this is usually abbreviated, yours for example is GRY short for grey or gray whichever way you want to spell it

    simply follow that circuit number to where it leads, tricky part is if it changes pages like this one does, in which case you switch pages and look at the connector or fuseblock on the next page and follow the same circuit number back up from there, looking for whatever components it comes into contact with. there are some basic symbols you need to familiarize yourself with but its pretty straight forward.... your #8 for example, at the fuseblock you see there is a squiggly line that looks like a sideways "S"... that is a symbol for a fuse so #8 goes through that fuse and the other side of the fuse connects to terminal #44 where according to that diagram a DRK GRN ( dark green) wire plugs into it ( I think this is your grey plug in wire location, sometimes the color changes over diff years but same thing, electricity doesn't care the color of the wire coating on the outside of it) ....that #44 circuit goes to your headlight switch and connects to its terminal 2 on the switch which is your dimmer control for the dash lights

    I suspect that you can simply supply 12V to the grey wire you unplugged and they should work according to the way I see it wired in the diagram.... that is the wire that feeds the dimmer in the headlight switch, no power in it and no lights, i would connect to any other location that can give it 12V and see if they work, if they do then the problem is either a fuse or in the fuseblock

    Reasons for no power at fuseblock terminals :

    I've seen the following :

    corroded fuse, top tests okay but fuse blades have what appears as a fine white coating over them stopping current flow ( this is a chemical reaction between the fuse blades and the terminal as they are 2 different types of metal )
    ensure you clean BOTH the fuse blades AND the fuse terminals in the fuseblock, as both will have this oxidation on them

    corroded fuseblock interior
    drivers side rusted window channel, water enters runs down, soaks carpet around fuse block, over time humidity gets into fuse block, copper strips inside fuse block and fuse terminals corrode or turn green making bad connections
    correcting this involves some work as you must remove the screw attaching the 2 halves of the fuseblock that you find under the hood, in the middle of the block, the screw is made NOT to come fully out... after that, under the dash there are four screws, one in each corner that hold your fuseblock to the floor, remove them and your fuseblock should separate from the other 1/2 under the hood, it may seem stuck, this is from sealant used to prevent water infiltration... once separated you can turn it around and see if there is corrosion or even a wire that's broken off a terminal that feeds the fuse
     
    Last edited: Jul 18, 2020
  10. cordero51

    cordero51 Member

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    so I simply plugged the grey wire into an empty fuse terminal and the buzzer that reminds you that your lights are on would be activated still no lights. id imagine that's what that fuse is responsible because currently with the headlight switch pulled on (headlights running the car off) the buzzer does not go off as it would prior to this mess. I used a voltmeter and I had no power at all both terminals so the next step would be to just trace the wire from the fuse panel and see if there's any bad wires correct?
     

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