Boost gauge dimmer wiring problem

[Cubix]

sorry I get what you mean by the dimmer knob in the car now. Unfortunately it does NOT dim or brighten with that knob. The gauge's brightness is a set thing from the manufacturer and mine happens to dim about 30 percent.

[sroby]

cubix that's no problem Ill take the 30 percent. I am just light sensitive at night. this crap with my vision started with me I noticed while having to wear night vison on my last deployment in Iraq (2004) Now in my late fifties I have the first stages of a cataract on my right eye and anymore, the bright light intensity at night drives me nuts. Thanks for all the good input. Best regards Steve

[Wes]

Not sure if you solved the issue (too lazy to read) but this was how I wired my defi oil pres gauge


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[sroby]

Thx Wes, Do the defi gauges with this wire up/ Dim normal with the oem dimmer control? Just curious Thx Steve

[sroby]

I have an update on my boost gauge for the FRS/BRZ. the gauge I was using is a Boost gauge part no. GAU012 from new south performance. The gauge is a mechanical type. Apparently I ordered the wrong gauge. This one is there redline edition for the VW. It looked good for what I wanted so I purchased it thinking it was a universal type. While it might be, it is with the info and help from you guys here on the forum that helped me understand some good theories of operation in so much as Subaru wiring and lighting. The correct part no for us to use on our vehicles if you so desire to use this type gauge is part no GAU018.
I spoke with Steve over at New South Performance. apparently they were aware of the non dimming of most manufactures boost gauges not dimming when applied on most Subaru vehicles. Since that's essentially what are cars are as in the frs, they have come up with the solution. Steve gave me the new part number and ask me to send him that gauge and he would send me the proper gauge for the Subaru. He said his engineers have found out what the problem was and input the proper mode for dimming intergraded into the gauge circuitry. So the new gauge should be as I was wanting a truly plug and play gauge mechanical in nature, simple wiring without having to have an electrical engineering degree. Wire it up and it is suppose to illuminate and dim when you dim your dash lights. I know it seemed petty but Damn I bet I have spent 4 days on this crap. Ha. Anyway when I get the new gauge and installed If it works as advertised I will update my diatribe. Steve at New South Performance is a great guy and very knowledgeable about this. He says to the best of his knowledge their knew gauge is the only one out there with this circuitry that works like this on the market to date. Stay tuned Best regards Steve

[sroby]

Ultra I will let you know as soon as I get this unit in and wired in. Thx my friend. Steve

[Ultramaroon]

Originally Posted by sroby

Ultra I will let you know as soon as I get this unit in and wired in. Thx my friend. Steve

Thanks, Steve. From your experience, though, I think I'm shit outta luck. I have an old school mechanical pressure gauge with a incandescent bulb.

Fingers crossed for you. If it turns out as I expect, my plan-B will be to use a series resistor to dim it a little and call it good.

[sroby]

I sure will partner. I am looking forward to finishing up the sprintex . Just got off the phone with Doug at D B W motorsports a little north of Atlanta, Great guys. When I get it done He said come on up 100.00 He will throw it on the dyno give me some idea of what I am putting on the ground. If I am close to 250 I will be good. Real numbers if its anything over that that's cool too. Mainly trying to get the torque to around the 200 ft lb mark. Not interested at this time with the E-85 300 horses. Ill save that for the young whippersnappers. Ha

[DaveB.inVa]

If you have a mechanical gauge with an incandescent bulb you're not out of luck yet! In fact, yours may be easier.

I'm familiar with the wiring method used as Toyota uses the same reverse voltage method on the Tacoma. When I added an oil temp and pressure gauge I had to deal with it.

First off, you must have a gauge with the light having it's own dedicated positive and negative wiring. The gauge ground can not share the same ground as the light.

Subaru and Toyota use a PWM control has a 12V positive that is always 12V to ground. The negative varies from 0 to 12V to ground. So the negative may be 10V to the frame but from the lighting positive to the lighting negative it is only 2V.

Because of this, you must connect the gauge lights positive and negative to the gauge dimmer. For an electronic gauge, the gauge ground has to be separate from the lighting ground for this reason.

When I added gauges to my Tacoma, I used Autometer custom gauges. The gauges are electronic, but the lights are unique in that they have totally separate circuits with their own positive and negative wires.

Because the lighting circuit positive and negative can both be at a voltage higher than the actual ground of the vehicle, its important that you fuse both wires in the circuit.

On my Tacoma I tapped into the gauge wiring (it was a green and a green white wire on the Tacoma, I think its violet and black/white if I remember correctly for the BRZ) and added a 2A inline fuse to each circuit where I tapped.

One other thing to note, you really must use an LED for gauge lighting so that the dimming profile will match. Otherwise the factory gauges will be on full bright and you'll only see a little bit of light from the incandescent. Dimming the factory gauges down will result in practically nothing from the incandescent.

With my Tacoma, the Autometer gauges used a regular 194 bulb. I installed a Diode Dynamics HP3 5000k bulb to most closely match the Tacoma gauges. A lot of this was trial and error. Diode Dynamics has a brighter HP5 LED that fits in a 194 socket. I bought the HP5 6000k color LED's for my tag lights and tried them in the gauges. I found they were too bright and the wrong color. I finally backed down to the slightly warmer 5000k bulbs and he slightly less bright HP3 bulbs and am happy with them.

I suspect you'll have to do something similar to get what you want with the mechanical gauge.



For the gauge that dims to a certain level when it receives a 12V input, you're in good shape with the 12V input to the radio dimmer.


With my BRZ I used AEM gauges and have them set to red. I don't like my gauges to be very bright at all either. Fortunately, with the AEM's lowest setting with 0V applied to the gauge positive wire results in the gauges being the very same brightness as the BRZ factory gauges on their dimmest setting! I never even connected the gauge light control wire on my gauges.

My radio also has a dimmer input that I've set to red and its dimmest setting is also the same as the BRZ factory gauges on their dimmest setting!

I couldn't be more fortunate and happy with the results of this.


If you have a gauge that has a gauge ground that is the same as the lighting ground, you're not out of luck, just a little inconvenienced. You can buy separate dimmers that would run only the gauge lighting and connect the input to the rheostat to a 12V wire that is on when the park lights are on and then dim the gauges to the level you want.

You would also have to go this route if you use an incandescent bulb due to how the LED and incandescents are dimmed.

[sroby]

DaveB, Thx partner that makes a lot of sense. I am in the basement wiring now. I couldn't believe it USPS delivered my boost gauge on Sunday. I'm on it. So far this gauge looks different from the previous one. It only has Black red 12v and yellow to dimmer. If I hook it as the directions say. Which equates over to the FRS as the violet wire I have hooked to the red 12v on the gauge. black wire to grounded location under dash. Gauge lights up. If I hook in yellow dimming wire of gauge to dimmer wire on frs. light on gauge is on. If you touch dimmer switch to dim instrument lights the boost gauge goes dark. So it looks like for now its full bright or dark no dimming. I am going to try off of the radio dimming wire now. This crap is a whole lot more complicated than it really needs to be. You ground the dam thing you put the red wire to a 12v ignition on/ tap the yellow wire to the dimmer on the car turn on the ignition turn on headlight switch and it lights up dim the panel lights and the boost gauge should dim like most others would. Man oh man this is frustrating. Can you update me which wire on the radio harness is the dimmer wire. I thing the Frs and Brz should be the same. Thx so much Steve

[sroby]

DaveB, I'm just updating, I might have to go with a different gauge as no matter how I try to wire this 3 wire gauge I get it to power up but constant full bright. I am thinking it might have to do with its a 3 wire setup. red 12v black ground yellow for dimmer. I am at a loss man. Ill bet I have 4 days of trouble shooting. Anyway Ill get it sorted out just wanted to thank you again for your info I appreciate you spending time out of your day to respond. Thx again Steve

[DaveB.inVa]

sroby, sorry for the late reply. I typically only get online late on Fridays.

I looked at the gauge you have, it's very nice. I think you've figured out how the gauge dims though, I don't think the radio dimmer will help you. The dimmer wire to the radio is just another 12V input. When you turn the park lights on it puts 12V to the radio and it dims.

If they built a gauge with LED's and brought out a separate connection for the negative instead of tying it together in the gauge with gauge power they should be in business.

You may be able to get a separate dimmer and do what you want though. The Autometer 9114 may be able to work. You would take a 12V input that is on when the park lights are on to the dimmer, then the dimmer output to the gauge. Set the gauges where you want them, then adjust the autometer dimmer to match. If you don't adjust the gauge lights, this may be ideal. When you turn the gauges on, they'll all come up the same, but if you adjust one dimmer, you'll have to adjust the other dimmer to make them match.

I typically set and leave the gauges where they are. I was going to go this route with the AEM gauges but got lucky when everything matched from the factory when at full dim.

[sroby]

Ultra, I have good news on the boost gauge issue. I was in touch with Steve of New South Performance and has been helping me sort this out. I have to give him all the credit.
Initially I found them on our forum mentioned as one of our members owns a BRZ. He used to own a GTI and was talking about his boost gauge he was running. The picture looked nice and simple. I went to their website and ordered the gau 012 redline gauge. This is the one I I could not get to dim and could not figure it out. Steve responded to me by sending me their new exclusive gauge for Subaru wrx. Gauge no. gau 018. The difference between the two is the redline edition for vw, has numbers that can be seen without the gauge being lit. (without FRS light switch on). The wrx gauge will have to be wired with ignition switch on to keep gauge back light on otherwise it remains blacked out.
I attempted to wire this gauge up and had the same results. I looked at the schematic and was wiring it up for the dimming per what I was reading and advise from others on this forum. Gauge would work as advertised but no dimming capability yellow dimmer wire from gauge/ black ground / red 12 v ignition on. No dimming. I pulled radio and tried dimming input from radio on both gauges, same result. I called Steve we talked he was going to get with his Electrical Engineer who I believe also owns the 2010 Wrx that sorted this out for their company years earlier. Less than 1 hr Steve emailed me and called me. It seems that the reverse lighting crap that Subaru had was my issue. I was merely wanting to get the gauge wired to dim along with the gauge cluster as factory like.
Steve came through for me in a simple solution. It looks like on the gau 018 gauge, Black wire to good ground/ red gauge wire to Frs (red/blue stripe) wire coming from main harness bundle by your left leg under dash.( or any source 12v ignition on). Here is the dimming wire solution, Use yellow dimming wire from gauge to Black and white striped wire from frs/brz factory dimmer and just like that gauge dims as factory gauge cluster. Ignition on turn on light switch gauge lights up. dim or brighten up factory dimmer and boost gauge dims and brightens right along with factory gauges. I cant thank Steve enough from New South Performance. So anybody looking for a simple mechanical boost gauge 3 wires install to work with factory like results, he has you covered. Thx so much for the forum members input and helping me keep my old mind ticking. I will get it all finished up tomorrow ridin out the hurricane and post some pics. Big thanks again for taking time out of their day for me in reply postings. Wes//DaveB/ Cubix/ Ultramaroon. Best regards Steve

Added pics of the boost gauge