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Scotty_Rah

Dash Gauges Not Lighting Up

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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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post-103290-0-28374500-1489056609_thumb.jpg

post-103290-0-27388100-1489056630_thumb.jpg

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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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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

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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

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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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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 :)

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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

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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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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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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

post-101663-0-41754200-1489273376_thumb.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

post-101663-0-78108800-1489243291_thumb.jpg < Click to see notes

Edited by GongZ

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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 . 

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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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I am still having issues with this gauges but have found that i have a short somewhere as my Tail.Park fuse blows as soon as i put it in the little fuse clamps - I believe this will affect the gauge lights. so i guess i have a more serious issue somewhere.. I have had a look at my tail light globes and connections, cleaned them, and then unplugged them to start testing for the short and when i put in a new fuse it blew straight away again.

I also had a aftermarket look wired in from the tail light loom, but I've removed that and put the loom back to normal... and yet she still blows.

 

I'm wondering where else should i be checking for shorts in this circuit? I've downloaded a wiring schematic but its for a '74 260 and mine's a '76. Also reading these hurts my head..

Edited by Scotty_Rah

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Unplug the taillight loom upfront at the kick panel. Put fuse in and see how that goes. Then you'll know if it's the front/dash or rear that has the short.

 

Once you work out front or rear you can start isolating bits in that section e.g. unplug number plate light or park lights up front.

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There is also a plug in section under the drivers seat which you can isolate the rear electrics with . That way you can confirm if the fault is in that vicinity or not .

 

                                             Regards : Alan .

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