3 Bar MAP sensor wiring faq

[WFO]

Originally posted by Razor
New wiring for 12223861 or 213-1562
A=ground
B=signal
C= 5v


Heres the answer then..if you have a GN..its plug-n-play.

Letters are stamped on the sensor.

hmmmm...i bought a brand new gm 3 bar map sensor a couple years ago that never worked with my boost sensing harness .

ken mosher checked my harness and said all was copacetic...i wonder if i got one of the old ones and the harness was made for the new?

any idea when gm made this change?always a possibility that an old one was still hanging around too..

 

[Razor]

WFO..I guess you now see why I posted this. When did they make the change..dunno..you can try reversing the wires and trying it again..whats the worst thing that coulds happen..

If its working, a digital voltmeter will read 1.65 volts on the green center wire with ignition on, car off.

HTH

 

[Two Lane]

Originally posted by Razor
That resistor is there to calibrate it to the factory dash boost guage..someone at GM fugg'd up.. take it out and plug in straight..as soon as you turn on the key, the guage reads 1 PSI not at zero.

Resistor drops the voltage to the sensor..down to like 4.7 from 5 volts. That also drops the zero point from 1.66 to like 1.5 hence the guage reading differently.

Any way to use the 3-bar AND have the boost gauge operate normally?

 

[Razor]

On a GN.. the little led's..no.. not without a converter, probably more trouble than its worth.

Reason is as follows. The 2 and 3 bar work on 0-5 volts. When you turn the ignition on at zero vacuum, the 2 bar reads 2.5 volts. The 3 bar same condition reads 1.66 volts.. Your factory boost guage works on 2.5v-5v aka 0-15 PSI boost. A three bar MAP sensor at 15 PSI is 3.3v.. which is about 5 PSI on the LED's.

I was actually working on a converter to use the factory LED guage as an alcohol pressure guage. Where it can be used in conjunction with a pressure sender and used to trim output pressure..like a x10 feature whereas 15 psi on the led's = 150 PSI alcohol..

But thats a winter project..in Florida

Am I giving away ideas again

 

[Two Lane]

Originally posted by Razor
On a GN.. the little led's..no.. not without a converter, probably more trouble than its worth.

thats a winter project..in Florida

Thanks...

 

[Razor]

Two Lane, in the case of the TTA, maybe. That resistor drops the voltage to the map sensor down to 4.7 from 5 volts. So the whole range is affected.. In other words, at 5 volts zero vacuum, the 3 bar puts out 1.66 volts. With the resistor in place, it drops down to 1.57 approx. So 1.57 is 0 PSI on the TTA guage. If you bypass the harness and run it straight, when you turnon the ignition, the guage goes up a lb approx. Problem is if your trying to track up to 30 PSI, dropping the voltage on the sensor limits its range to 4.7 vs 5 volts. Not a problem unless your running high boost and using a FAST or one of my PAC controllers. Maybe putting a resistor network(2 resistors) on the green wire going to the sender may get it to correct the guage.

Havent had anyone ask.. and yes to the boost pressure guage for the TTA alky ..

coming soon

Maybe someone can do this so I dont have too

 

[Six_Silver]

Is the FAST harness wired for the new style (12223861) or the old style? I am guessing the new style?

 

[87Limited2Turbo]

Those purchasing new 3 bar map sensors from AC Delco part numbers 213-1562 or GM 12223861 the sensor is wired internally different than the original TTA 3 bar.

The correction involves swapping the power and ground terminals to it. Whereas old sensor wiring is
A= 5v
B=signal
C=ground

New wiring for 12223861 or 213-1562
A=ground
B=signal
C= 5v

Hope this saves someone from buying the GM harness that reverses the wires for 30 bucks

This only applies to 3 bar map sensor users

ok i have a question. just hooked up my MAP (5v from tps and ground to body) my plug pins out like this:
A=ground
B=signal
C= 5v

does my plug being wired this way mean my motor is more than likely from a turbo trans am ???? and not a GN as i was told ?

 

[Razor]

All that means is you have a very old MAP sensor,

TTA motors have 3 center bolt valve covers. Buicks have 4 bolts to hold the valve cover

 

[bigal915]

so if you have a boost sensing harness does that do any good for the gn?

 

[Razor]

so if you have a boost sensing harness does that do any good for the gn?

No unless you have the old turbolink setup and are tryin to record boost.