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Dash Gauges Not Lighting Up

Gauges Dash electrical wiring

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#1 Scotty_Rah

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Posted 09 March 2017 - 08:54 PM

Well.. I've searched for a topic on this to see if any other people have had issues, and didn't manage to find any answers to my problem. Sooooooo.....

 

Help please!

 

I have been trying to figure out why my gauges aren't lighting up when i turn my accessories or headlights on. To save some time, i'll list the things I've already tried and observed.

 

1. I have tested all my fuses and fusible inks with my multi-meter - my fusible links look real sh*tty but they are still passing a current

2. I have removed my smaller gauges (clock, Volt/fuel gauge & temp/oil) checked the bulbs and wires. My fuel gauge and volt gauge is the only gauge that gives me readings. The rest I don't think are hooked up to my engine as It's an RB30.

3. I've turned my dimmer up and down. - I tested this with the multi meter but it didn't give me any readings. I unpluged it and tested the terminals inside and still no reading.. Whats that all about?

4. my high beam looks to have been modded to a floor switch next to the clutch pedal. the wiring has been re-located to this. .... perhaps this might be where my power to the dimmer has gone to??

5. When i put my high beams on the high beam light will light up, as does the brake light.

6. My Taco doesn't work.. not sure if its been wired into the RB 

 

That's about everything I've done and noticed. I've got some photos of some of the above mentioned things..

 

 

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#2 Cozza

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Posted 09 March 2017 - 09:14 PM

6. My Taco doesn't work..

Have you checked your fajita??

Ahh sorry couldn't help it. 😂

It's really hard to diagnose electrical gremlins from a distance and it sounds like you've got a bit more checking to do but...
- when you say you checked your dimmer with the multimeter and you got nothing, what did you do? Was it open circuit all the time? Did you try bypassing the dimmer?
- Have you got a wiring diagram? If not get one from the FSM and work methodically confirming where you have power and earth until you find a problem.
- which brake light comes on with high beam? The warning light on the dash or the rear brake lights?

Good luck
Mick
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#3 PB260Z

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Posted 09 March 2017 - 09:14 PM

Hi Mate

Can't really be sure without having the car in front of me but,

No power at the dimmer switch is where I would start. Maybe even hotwire it and see if the guages light up.

No tacho - The original internals of the tacho wdon't work with modern ECU signals, They can be modded to pick up the pulse from the RB ECU.

High beam and Brake light - are they coming on at 100% or somewhat dim, if dim possibly a bad earth.

Sounds like someone has had a lot of fun with wiring around your dashboard.

Cheers

PB

#4 Andrew_L26

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Posted 10 March 2017 - 12:43 PM

I would probably start with the dimmer, which is just a variable resistor It when checking the resistance of the potentiometer it should change as the knob is twisted. I would try temporarily re-routing the wiring for the high beam back to stock to see if that helps. I would also check the "FLASHER" fuse as it is connected to most of the internal gauges and will stop the tach from working if it is broken. I think that manually jumping power to the dimmer pot may be useful, I would see if that causes the lights to function. If so then you know the issue is probably something to do with the headlight (relay?) on the floor. If that fails then you could try taking one of the gauges out and connecting power to the lights that way, if they all light up then you know the fault is somewhere between the dimmer pot and the gauges.

*Make sure that you check the polarity of the wires going to the globes and dimmer before connecting any jumpers, disconnecting the battery may also be a wise idea when jumping.

 

Andrew



#5 zeds4ever

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Posted 10 March 2017 - 04:38 PM

Suggest you don't power up dimmer unit as it is a ground control set up . The green/white stripe wire that runs to your gauges is the power circuit , check you have supply there by using a test light set up or your multi meter . The dimmer has a internal resistor which sometimes breaks down which means it wont work. Try to disengage the connection point just near the back of the dimmer & connect a wire into the two sections of the connector itself that leads from the dimmer unit to the gauge lights , should be a red /blue stripe from memory .Just been thru this myself.

PS : Check that you have no shorts by disconnecting your battery Negative cnctn then set your multi meter to read up to 20volts , connect one end to the Negative wire off battery & the other multi terminal to the battery Neg trmnl . You should get a Zero reading anything other than that means problems .

Also if you look at page 7 in the electrical section of the Forum you will find a wiring diagram that is very helpful .                                                              

 

                                                   Regards: Alan.


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#6 Scotty_Rah

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Posted 10 March 2017 - 09:48 PM

Thanks gents,

 

You have given me some stuff to try out over the weekend.

 

I will report back after I've carried out the checks :)



#7 Scotty_Rah

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Posted 10 March 2017 - 10:01 PM

Have you checked your fajita??

Ahh sorry couldn't help it.

It's really hard to diagnose electrical gremlins from a distance and it sounds like you've got a bit more checking to do but...
- when you say you checked your dimmer with the multimeter and you got nothing, what did you do? Was it open circuit all the time? Did you try bypassing the dimmer?
- Have you got a wiring diagram? If not get one from the FSM and work methodically confirming where you have power and earth until you find a problem.
- which brake light comes on with high beam? The warning light on the dash or the rear brake lights?

Good luck
Mick

 

Where do i find the fajita? Is that located near the indicator fluid reservoir?  ::)

 

- when i checked the dimmer, i unplugged the terminal to it, turned my headlight on and checked both terminals(not knowing which one was ground) I also checked the terminals on the back of it too.. 

- I have the wiring diagram in my manual and also downloaded one from Atlantic Z , but i don't really know how to interpret it. it kinda makes sense, but is a little overwhelming.

- the warning light on the dash that is connected to the handbrake switch. 

 

-Scotty



#8 zeds4ever

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Posted 11 March 2017 - 10:20 AM

G'day Scotty , if you have trouble with anything give me a call on mob #0405 291 467. Might be easier to talk you thru it . 

 

                                                           Regards : Alan .


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#9 PB260Z

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Posted 11 March 2017 - 05:14 PM

G'day Scotty , if you have trouble with anything give me a call on mob #0405 291 467. Might be easier to talk you thru it . 
 
                                                           Regards : Alan .



#10 GongZ

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Posted 12 March 2017 - 12:26 AM

Suggest you don't power up dimmer unit as it is a ground control set up . The green/white stripe wire that runs to your gauges is the power circuit , check you have supply there by using a test light set up or your multi meter . The dimmer has a internal resistor which sometimes breaks down which means it wont work. Try to disengage the connection point just near the back of the dimmer & connect a wire into the two sections of the connector itself that leads from the dimmer unit to the gauge lights , should be a red/blue stripe from memory.

 

I am following this topic with great interest.

Scotty has a 260Z - so Alan is correct about the way the instrument lights work.

 

260Z tachometer

260Z tach.jpg  < Click to see notes

 

I just thought I would point out that 240Z's are not wired this way. In 240Z's, the power connects through the dimmer (rheostat) to the instrument light bulbs, and the bulb sockets are earthed through the metal body of each instrument.

240Z tachometer

240Z tach lighting socket.jpg < Click to see notes


Edited by GongZ, 12 March 2017 - 09:04 AM.


#11 zeds4ever

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Posted 12 March 2017 - 01:15 PM

Sorry Scotty , but I gave you a bum steer with regards to no reading when connecting a multi meter to disconnected Neg grnd battery wire & Neg terminal on battery , you will get a reading of about 12.7 volts which comes via the vltge gauge which operates at all times . Unless you have one that is wired up different .

 

                                                                           Regards : Alan . 



#12 Scotty_Rah

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Posted 12 March 2017 - 09:19 PM

Hi guys thanks for the info. Unfortunately i've had very little time this weekend to get out an work on my car, as I had my mother up from Tassie visiting. 

 

I'm going to try to allocate time after work to do the checks. I'll try to document as much as possible and relay back to here.

 

Thanks,

 

-Scotty


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