Search is pretty crappy on results. and I have reviewed the wiring diagrams for the Cluster gauges.

I want to get my stock boost gauge in the cluster working with my Haltech E8.
Programming an output on the E8 is easy.

BUT I cannot find the input pin on the wiring diagram for the boost gauge. There is NO labeling for a Turbo cluster gauges that says boost OR Pressure sensor.


What I do see is a wiring tap from the MAP/pressure sensor to the stock ECU 2H connector.

 

I'll have to check my notes from 3 years ago, but I had to do the same thing when I switched to an AEM Infinity ECU. The gist of it is I retained the stock MAP sensor just to drive the dash boost gauge (the AEM Infinity gets its own 3 bar MAP sensor), and got a separate 12VDC to 5VDC converter/power supply to provide the +5VDC supply to the OEM MAP sensor & dash gauge. Wiring to tap the input to the dash boost gauge was accessible thru one of those "X" connectors by the ECU; drawing a blank on which one & what wire color to tap. My goal here was to keep the dash boost gauge fully functional, but completely electrically isolated from the AEM Infinity ECU.

 

Cool. But I used the stock map sensor wires for the Haltech Map sensor. So going to try use stock sensor is not an option.

 

I was wondering about this as well a couple years back. Hadn't got around to fooling with it. I found a couple pictures of the boost gauge circuit board. I forgot to take a picture of the underside, but there's a little bit more to it. As far as doing a true adaptation, you would likely leave the Vin line as coming straight from your MAP sensor. From there, I think it could be a matter of adjusting some of the resistor values to adjust the output. If you know your voltages for certain boost values, I'd hook in some potentiometers so you can tune the circuit so the gauge lines up correctly. I'd probably then measure the potentiometer resistance and try to make a solid resistance replacement to fix the circuit in place. I haven't done it yet, but if I ever get around to going aftermarket, this is on the list. Would make a pretty good write up if you have a good solution.

 

Great images.
I am thinking you could test this with a voltage range of 0v to 5V to the inputs on the gauge you have there.
find the voltage for -20, 0 and then +45 and put that into Excel and calculate the values.
I am looking into my Haltech E8 and wish there was an analog voltage output that I could output to a pin. Looks like we have to scrap that idea with an older E8 an outputting the boost info from ECu to the gauge

 

Ok, gotcha, I did a full custom wiring harness for the ECU, so none of the 30+ year old OEM wiring was used between sensors & ECU. Didn't want any "mission critical" engine management functions relying on old wiring. For the ancillary stuff that shared the OEM ECU/emissions harness (i.e., wiper motor, cruise and re-purposing the OEM MAP sensor for the dash gauge, etc.) I just built a sub-harness for that stuff, using re-pinned OEM connectors.

 

I would imagine mapping it to an analog ecu output would probably be the easiest like you said. You would then only need to run a single wire to your dash connector and de-pin the stock input pin that carries the new sensor voltage.

If you don't have an analog out, gotta mess with the gauge circuit to accept new voltage range somehow.

I'm glad we've been getting a lot of good electronics posts on here in the past couple years.

 

i ran a wire for mine, and teed it into the map sensor like the stock setup. you must have a different diagram, as i was able to figure mine out really easily.

my car has an FD map sensor, because its an FD swap, so the gauge is off a little, but its so hard to read its not really noticeable

TLDL? yes just run one wire with the same output as a 2 bar map sensor, and it will work