Gauge illumination

[rdefabri]

I've posted on other threads about my OEM radio install - I've gotten 99% of it done. Radio works, speaker connected, antenna goes up/down and even the dial is illuminated (with jump to proper fuse).

Interestingly, my gauges don't appear to be illuminating. I say "appear" because the car isn't running or started. I simply have accessory on. However, my front lights go on, and the radio illiuminates.

So dumb question - do the gauges only illuminate when you start? That can't be the case, but I am just checking. Note, they worked fine before I installed the radio, but I'd be shocked if I knocked something out or cut something - I didn't. And, as I noted, I CAN get the radio illuminated.

Thanks,

Rich

[Arne]

No, the gauge illumination should work any time the lights are on. But as I recall, the radio light is fixed brightness, while the gauge lights go through the dimmer rheostat. Is the dimmer turned all the way dim (off)?

[rdefabri]

Checked the rheostat...adjusted both ways, still don't see any gauge illumination.

I'll try it with the lights off. I know these cars aren't noted for it's bright gauges, but it was pretty dark when I did it last.

***** EDIT - just checked, they aren't illuminated! Darn it, I won one battle only to encounter another.

Edited February 2, 2009 by rdefabri

[EScanlon]

But can you DIM it?

If you cannot, then you may have disconnected the rheostat. Alternatively, you've plugged the radio face light into a circuit that's on in the ACC mode but not connected to the Instrument Light Circuit.

Look for the Red/Blue wire connected to the rheostat and do a continuity check to it with any other R/B wire you have in the console area and you should be able to find a connection for the radio.

By the way, the original radio only put out about *3.5W into 4Ω Mono.

If you hook up two 4Ω speakers in series, you'll over load and overheat the radio by a total of 8Ω in the circuit, twice what it was designed for.

But, by connecting two 4Ω mono speakers in parallel it actually reduces the total resistance load to 2Ω. You won't be able to power the two speakers very loudly, but it will usually be sufficient to hear fairly well if you have soundproofed your car to any extent.

Don't expect high fidelity or static free sound either, the OEM radio had a 10% THD, that is TEN percent and not a tenth or hundredth. Remember, just the fact that it could tune in the FM band was considered an upgrade from a strictly Mono AM only radio. Stereo FM followed thereabouts but the radios had already been manufactured and installed.

FWIW

E

[rdefabri]

Enrique,

I can't dim the radio illumination, if that's what you meant (I believe it is), so I'll start at the rheostat.

I connected only 1 speaker, so I know I am good there. The radio is far from perfect, but because it's OEM, it's perfect for this app

On another post, I had alerted readers that I am an electrical moron. I can figure some things out, but I am all thumbs otherwise. I am smart enough to put wire "a" to wire "b", but testing things isn't my strength. It hampers me tremendously, which is why I am asking loads of questions.

A point to note - I had a single red/blue coming out of the back of the radio. I stripped the edge of the wire, and slid it around the top right fuse (where the red/blue wire from the main circuit terminated). When this was not attached, the gauges didn't light either, so I suspect I must have done something wrong prior.

Now, I disconnected no connectors. I only connected the newly installed OEM connectors to the appropriate unused connectors in the dash. I also know that I cut no wires that weren't explicitly radio-related. So either I have a short or I did something improper. Given the electrical moron label I wear, I think it's the latter.

I'll start at the rheostat and work backwards.

Edited February 2, 2009 by rdefabri

[Zs-ondabrain]

Do us a favor and Step out of the Car when you turn the parking lights on.... Are the parking lights on, outside the car??

The Parking light fuse is the 3rd fuse down on the right, in the fuse box.

You mentioned using the upper right hand fuse to test the lights. I think that fuse is for the right headlight. Just FYI.

I know you said you did'nt Unplug anything but it's a 240Z, you need to get under there and check first hand. $^!# happens and usually without you knowing it happened.

[240znz]

The rheostat is connected in series with all gauge illumination lamps. The rheostat is prone to falling apart which results in the illumination circuit being severed. A bit brittle they are. Just put your hand under there and feel about for the rheostat, if your fingers come back out with electrical bits, then it's a new one you'll be after. Good luck, they are hard to find in working order as most suffer the same fate.

There must be an alternative replacement part that someone has found. If anyone knows of such a part, please post it here so we can all get new ones.

My guess is that you couldn't replace it with a potentimeter as the POT's are rated for the load???? What is load anyone?

[Zs-ondabrain]

not sure on the last question but the Parkingl ight fuse is a 15 amp fuse. Minus the outer parking lights and I'd say the dash lights are 1/4 of the original load of the entire circuit.

[EScanlon]

I can't dim the radio illumination, if that's what you meant (I believe it is), so I'll start at the rheostat.

...snip...

A point to note - I had a single red/blue coming out of the back of the radio. I stripped the edge of the wire, and slid it around the top right fuse (where the red/blue wire from the main circuit terminated). When this was not attached, the gauges didn't light either, so I suspect I must have done something wrong prior.

....

By connecting that single R/B wire FROM the radio directly to the fuse box you connected INTO whatever circuit you used. If it's part of the Headlight or Parking light circuit, the radio's light WILL light when that circuit is actuated, but at full strength (i.e. no dim possible).

That your instrument lights did NOT function before, and still don't, underscores that the radio light is NOT part of the instrumentation light circuit.

In the wiring schematic, you'll find that the R/B wire from the radio connects to the R/B wire connecting all the instruments between the Amp/Fuel and the Water/Oil connections. This points out that the radio was intended to be dimmed along with the instruments.

To determine if your rheostat has gone bad, connect the two wires going TO the rheostat to each other. This will remove the rheostat from the circuit and you should see the instrument lights go on. If they do NOT, then your problem is either at the Comb. Switch and you probably do NOT have Park Lamps; or it's after the rheostat connection if you DO have them. The two circuits separate at the connection to the rheostat.

FWIW

E

[rdefabri]

Do us a favor and Step out of the Car when you turn the parking lights on.... Are the parking lights on, outside the car??

No parking lights. No rear lights either...but brake lights when I tap them.

To determine if your rheostat has gone bad, connect the two wires going TO the rheostat to each other. This will remove the rheostat from the circuit and you should see the instrument lights go on. If they do NOT, then your problem is either at the Comb. Switch and you probably do NOT have Park Lamps; or it's after the rheostat connection if you DO have them. The two circuits separate at the connection to the rheostat.

I'll check this. I realize someone said they are flimsy, but it was working fine prior. Doesn't mean it didn't get roasted, so I will check it.

In the wiring schematic, you'll find that the R/B wire from the radio connects to the R/B wire connecting all the instruments between the Amp/Fuel and the Water/Oil connections. This points out that the radio was intended to be dimmed along with the instruments

This is where I run into trouble. I see why connecting directly to the fuse box wasn't optimal. But I don't know how to get the single R/B wire from the radio into the circuit. Can I join it where the main R/B joins in at the fuse box? It looked as though it was the top right fuse, which is why I connected there.

Edited February 2, 2009 by rdefabri

[Arne]

No parking lights. No rear lights either...but brake lights when I tap them.

Time to take a good look at the parking light fuse. As mentioned above, I believe it is the middle fuse on the right.

[EScanlon]

...

This is where I run into trouble. I see why connecting directly to the fuse box wasn't optimal. But I don't know how to get the single R/B wire from the radio into the circuit. Can I join it where the main R/B joins in at the fuse box? It looked as though it was the top right fuse, which is why I connected there.

As Dave has pointed out, the Top Right fuse (as viewed from the fuse side of the fuse box) should be one of the Headlights (Left). Since you traced a R/B wire TO the fuse box, I'm wondering if you might have noted the R/B wire that connects the Accessory relay when the fuse box is viewed from the bottom (connection side), it then becomes the Upper Right connection which, when viewed from the fuse side down, that connection is the Upper LEFT and not the right.

Connecting the radio's R/B wire to it's corresponding wire isn't all that hard. Ideally you should be able to locate the wire in the wire harness right by the radio's position. Once you find it, getting a bullet connector onto the bare wire should not be a problem, or you can just splice into the wire.

If you can find an R/B wire but want to make sure that it is part of the instrument light circuit, connect a circuit checker (basically a battery and a light bulb in series with a wire and a probe) to the R/B wire that connects to the rheostat and the R/B wire you found. If the light lights, then you DO have continuity between those two wires. Once you rectify the problem with getting power to the instrument lights you'll be able to dim the radio along with the instrument lights.

Now, one more check. Run a wire from the MIDDLE RIGHT fuse outer clip to the R/B wire that connects to the rheostat. Turn Combination Switch to the Park position and if your instrument lights light up.... you know they work and can narrow your search to the Rheostat or to the Combination Switch. If they do NOT work, then you need to check the Dash and the Combination Switch Grounds.

By the way, I've seen rheostat that have been deemed "failures" actually just need a slight tweak of the wiper to make tighter contact on the resistance coil. Removing the rheostat is kind of difficult as the screw holding it to the dash's frame gets inserted from above and down. As a result you'll need to use mirrors to even see the rheostat and it's mounting screw.

But if you've joined the two wires that connect to the rheostat and you still do NOT have instrument lights, then you have a problem further up the circuit, meaning the combination switch. The fuse is a possibility, but check if you have power to the engine bay trouble light, if you do, then the fuse is working ok. (Then again, just pull the fuse and check it.)

Which is what you described in your last post. You don't mention whether you do have headlights or not, but if you do then you know that power is getting TO the combination switch but not getting to the parking lights.

FWIW

E

Edited February 2, 2009 by EScanlon