ahyc84

does anyone know where the wiring from the gauge goes to?
is it the boost sensor by the shock tower?

or does it tap in to one of the wires that goes to the ECU?

trying to get the boost gauge to work on the t2 cluster, with my NA harness on the NA chassis. Yes it has a j-spec factory turbo engine...lol

last owner used NA harness on the turbo engine, so quite a bit of the things are frankenstein together.


thanks

HAILERS

Only God knows why anybody would want a boost gauge in place of the voltmeter. The boost gauge isn't very accurate.

The online wiring diagrams show that the boost gauge gets fed from the output wire from the boost sensor. That wire has a splice in it that has one half of the splice going to the ECU pin 2B on a series four, and the other half of the splice going to a mating plug b/t the emissions harness and the front harness.

That's just the signal wire. The ground wire for the boost sensor leaves the gauge and travels back to the mating plug b/t the front and emissions harness and gets spliced into the ground wires for all the sensors.

Bottom line is that you'll have to run a wire from the boost sensor output wire to the right pin on the gauge and then find the right pin that is ground on the gauge and just ground it nearby.

You'd need the wiring diagrams for the car. Plus the pinouts for the combination meter are different on a non turbo vs a turbo.

By the way, I use a non turbo harness on a turbo engine and there is not a thing Frankenstein about it. What is Frankenstein about your car.....and the only thing that would make it that way, is using a turbo combination meter out of a turbo car with a non turbo front and emission harness. There is NOTHING to gain by putting in a turbo combination meter but a boost gauge that is marginal at best and you lose the volt meter which is near the top of the list of things you want to work. In my humble opinion.

The output wire at the boost sensor is Brown with a Red stripe. The same color wire is found at pin 2B on the ECU.

You need to have the schematics for a turbo and non turbo combination meter and its plugs in order to run those two wires to the meter. The fsm is free and online at this site.

turbo2SE

iTrader: (1)

i got the same setup as you friend i just went the easy way out i used my non turbo cluster cause i also have the non turbo electrical harness plugged in so i just bought a autometer boost gauge and tapped that into my vac lines plus its more accurate then the stock turbo 2 boost gauge

SureShot

The ECU gets the boost sensor signal, then it creates (through some undocumented internal magic) a signal for the dash gauge.

The dash gauge connections are the weak point.
If they are not perfect, the gauge reads low.

In this short video, you can see the difference between the dash gauge & the mechanical boost gauge on the A-pillar.
Link to video (1.9MB avi)

HAILERS

I don't see things like that. In the emissions harness the output wire, brown/red has a splice. It goes to two points. One is pin 2B on the ECU and the other is to a plug called X-15 on a 87 series four or FEM-01 on a 88. From FEM-01 it heads for the C0-3 plug and then to the CO-2 plug. See section Bb-2 in the 87 FSM. I forget the page for the 88 FSM, it's not handy. That is for the input to the gauge. The ground for the gauge is inputted on C0-3 and comes from X-15 plug (FEM-01) and ties to the common ground for the sensors, the brown/black wire. See Bb-2 and section C of the 1987 FSM.

The 1986-1987 wiring diagrams are better, superior, the best of the best of Mazda wiring diagrams. The 88 and on suck.

I can post jpgs for doubters. The ECU has nadda to do with the boost gauge. It just shares a output from the boost sensor.

ahyc84

well i got the wiring diagram and all, i just couldn't find any info on where it's linking to

i'm still trying to decide if i wanna just take the temp gauge from the turbo cluster and move it in to the NA cluster. I don't really need the majority of the crap on the stock gauge cluster once they fix the shipping error on the microtech LT10. i'm gonna run a LCD touch screen and a small computer in the car so it shows all the gauge i'd ever need. Cost about as much as getting a whole series of gauges

i think in the end, it might be a better choice to just replace the temp gauge...

HAILERS

Here's some jpg out of the 87 fsm. No order to it.

3RotorRocket

Mine didn't use to work until I cleaned my engine bay real good...then all of a sudden it worked.Get a aftermarket boost gauge forget that stock cluster gauge it's useless.

- Aaron -

HAILERS

I see why people think the ECU makes the gauge work. At the bottom of the third picture, it shows a wire out of the gauge and the words to the effect that that wire goes to the Emissions Control Unit. Sorry, it ain't so. It goes the brown/black wires that are all spliced together for a ground for all the sensors. I do admit that they ALL terminate at pin 2C on the ECU and are grounded in the internals of the ECU. So.....I understand now why the confusion/crossed swords etc.

That said, you still could take that wire from the boost gauge and just ground it on any chassis ground and the gauge will work just fine. In fact I'd suggest BETTER.

The third picture: https://www.rx7club.com/forum/attach...hmentid=147007