3 bar map with digital dash

[57 chevy]

digital dash-alky

thanks lpaulabbott,
but still little confused. does my factory digital dash have an analog plug, and where is it? also where do i plug it into what ? my 3 bar is a mototron that already is pluged in from harness from tps.

 

[pacecarta]

the digital dash and analog dash cars differ in the dash side harness

the engine harness for both dash types are the same ,the harness runs up too the ecm and the connector behind the glove box right hand side

the digital uses the connector for the hobbs switch to drive the boost lights in the digital gauge cluster , it doesnt use the map sensor so the wires arent present in the dash harness and the map connector under hood the wont have any power or ground

the analog uses the map connector to a 2bar map sensor to drive the analog dash cluster boost gausge , with that dash the hobbs connector is inactive

the MAP gets its power from the boost/tach module thats in the analog gauge cluster , if you dont have that either because you have a digital dash or because youve changed to a gnx type dash or cyberdyne then youll need to make the map connector under the hood active

you say already have a harness for the map from the turbolink plug and play which you're using now on your powerlogger so doing any additional wiring to make the sensor work isnt required
the signal from center pin (B) can be used for the powerlogger and the alky map input (green wire at PAC) but your sensor output needs to be showing 1.6V at the center pin @ atmosphere (no vaccum - key on engine off) , with 3.0v would cause the alky to be on at all times
not sure if this the case but 3v at 0psi sounds like the sensor might be wired backwards on the ground and power (OE TTA sensors were backward of the replacements (A and c terminals) and required an adapter harness that flipped those wires.
if your sensor is wired correctly and doesnt show 1.6V then youll need to get one that will like the GM replacement 3bar sensor for the TTA

 

[57 chevy]

digital dash-alky

Thanks pacecarta, but more questions.
where does the 1.6 volts come from at the 3 bar? is it from tps wire that runs to the 3 bar or is it from the 3 bar to the tps? confused as to which direction the voltage flows.

if i get the correct 3 bar that should have the 1.6 volts, would i have to power the turbo-link from a different source or do away with the turbo-link. do you know of anyone else that has the alky with digital dash & turbo-link ?

i have been considering getting the powerlogger but have been very happy with the turbo-link.

 

[pacecarta]

the ecm sends 5V to the tps , the tps outputs a signal from 0 to 4.9V at pin B (TPS signal) which is fed directly back to the ecm so it knows the TPS position , with idle set at .42- .44V and WOT set over 4.5V or so the ecm knows the relative position of the throttle blade determined by the returning signal voltage ,

the turbolink harness taps into the TPS wiring at the 5v input at the TPS and ground and jumps it to the map sensor

a map sensor works similar to the tps but it uses vacuum or pressure to affect the signal voltage much like the tps uses the arm

with 5V applied to pin A of map sensor and ground at pin C , the returned voltage on pin B is the MAP signal voltage ( based on vac/boost level at the sensor port )

a 3 BAR sensor is rated to read 3 BARs of pressure ,1 BAR vacuum and 2 BARs pressure
BAR is metric measurement and 1 BAR = 1 atmosphere or 14.7psi

with a 3bar map being fed 5V (the 5V is tapped from power to the tps sender) and ground at pin C the voltage at pin B should be
0 V is 14.7psi vac, 1.6V=0 psi and 4.9V= ~30psi

so at zero vac(or zero psi ) the MAP sensor should return a value at pin B of 1.6V besure you have this for alky operation , if not find a sensor that will

then just tap into the wire to the center pin of the MAP sensor (pin B) as close to the MAP connector as you can and run it to the pac controller (green wire), dont run (OR TAP )it to the turbolink adapter output as thats altered to be fed into the IAT(MAT) harness

and yes the orange and brown two color led wires connect to the orange and brown wires at the PAC

 

[57 chevy]

digital dash alky 3 bar

thanks pacecarta.
So do I need a 3 bar for my turbolink & a seperate 3 bar for the alky? concerned if i change the center pin from 3 volt to 1.6 that it will have an effect on the turbolink. also turbolink asside,if i did have the proper 3 bar, what type of electrical connection does it have? would it be something that would require running loose wires from different locations, or is there a plug in harness for the 3 bar. the more i read the more i think i am going to have to do away with the turbo link.

 

[57 chevy]

digital dash- alky- 3 bar

Pacecarta,
I can't thank you enough, I appreciate the time you have take to help me.
I have been measuring voltage at the harness that plugs into the 3 bar, without it being connected to the 3 bar. I connected it & walla 1.57 volts. will that be ok to run to the pac?

one last question. should I run 2 wires inside the car just for the purpose of adding powerlogger at a later date, or could I tap into the single green wire inside the car that will run to the pac?

I can't thank you enough. Sorry to be such a pain. Razor is very lucky to have someone like you to fill in during his absence. U R DA MAN.

 

[pacecarta]

its 1.6 at sea level , altitude affects the voltage , 1.57 is fine now connect it to the PAC green wire (make a solid connection) and get to tuning

and one wire is fine, you can tap into it as you need

 

[Razor]

Thanks a million Paul.

One thing is the T-link harness ties into the MAT circuit so it reads boost through the MAT(manifold air temp) input on the ecm. Becuase of this it changes the voltage on the 3 bar output. Yes it does get its power from the TPS and its ground. But the green(signal) wire gets altered becuase of its connection to the resistor used for MAT.

If you get a power logger, T into the green wire coming from the 3 bar and use that for its signal.

You guys are great..

Julio

 

[pacecarta]

Post deleted per Paul's request

 

[57 chevy]

sO ITS OK TO TAP INTO THE GREEN WIRE AT THE 3 BAR WHERE TLINK CONNECTS?

 

[Razor]

sO ITS OK TO TAP INTO THE GREEN WIRE AT THE 3 BAR WHERE TLINK CONNECTS?

As long as you have 1.6 volts output from the 3 bar MAP, you can do anything you want. If you dont have 1.6 volts.. then your back to square one on this.

T-link adapter gets its power from the TPS and interfaces with the MAT circuit. This MAT circuit interfacing is whats messing with the voltage. This is not an issue with the power logger as it doesnt mess/change the voltage from the MAP sensor.

This is what I would do, connect your t-link adapter and 3 bar MAP sensor. Turn the ignition "ON".. measure voltage on the center terminal of the 3 bar with the 3 prong weather pack plug "PLUGGED INTO IT". If it measures approx 1.6 volts.. tie into it by splicing the wire and your done.

IF the voltage reads way higher like 3 volts, then the interface is messing with the voltage and cannot be used. At this point your options are disconnect the wiring to the MAT circuit at the air filter and reconnect the MAT sensor to the OEM wiring and re-check your voltage.. this will mean you cannot use the boost logging feature. Or get a separate 3 bar for the PAC controller and leave your 3 bar for the T-link. Or get rid of the t-link and get a power logger if you must record your boost level.

The t-link is very slow at 1.5 frames per second. meaning a 10 second run you have very few frames of data 15. Versus a power logger has 18+ frames per second giving you over 180 frames of data in a 10 second run. So all this complication.. its probably better to upgrade your electronics to the power logger if you must record your boost level.

I dont think you'll end up having and eating your cake too on this deal. Meaning using the 3 bar map for both purposes "alky kit and t-link boost sensing". Only becuase of the way it attaches to the MAT circuit on the factory ECM. Hope i'm wrong.

 

[Razor]

Look what I found

I found a T-link boosty sensing harness in my "stuff"

What happens is it makes things confusing since the color "green" on the T-link is actually +5 volts on the MAP plug.

A=ground
B=signal
C=power(+5)

On the T-link harness green is C. On the Buick factory harness green is B. This adds confusion.

Now here is the kicker.. The A terminal(which is a black colored wire) on the T-link harness goes to the MAT sensor "-", and the B terminal(tan colored wire) goes to the MAT signal. So the ground for the MAP comes from the ecm through the MAT. And the signal is altered by the pullup resistor built into the ecm on the TAN MAT wire.

So... if you want to disable the T-link harness and use it to supply 5 volts to the 3 bar MAP, all you need to do is unplug the white female MAT plug, and ground the black wire on the MAP. Now you can attach the green wire going to the alky controller to the center "B=signal" which is a tan wire.. and whalla.. you'll have your 1.6 volts.

You cannot use the MAT input and have a normal scaling 3 bar MAP becuase of the ecm connection.

Now I thought of just cutting the tan colored wire and letting the ecm ground the black, but doing this poses an open circuit on the MAT.. which will give a "Check Engine" code for MAT. This is why unplug it, hook up the MAT sensor as OEM, and apply ground to the black colored wire going to the MAT plug.

Hope this helps the archives somehow.

 

[57 chevy]

t-link boost digital dash

Razor, my t-link harness at the 3 bar is as following. a-blk, b green ( not c ), c-red. the harness that is next to the hobbs not used is as follows a-blk, b-green, c-grey.currently, my mat is unplugged, the mat harness ( grey & blk )is plugged into the t-link harness that goes to the tps, then from the tps it goes to the 3 bar. with this set up I have 1.57 volts at the green b terminal at the 3 bar. the blk that normally plugs into the mat, does show ground, but not from anything I have done

It looks like my t link boost harness at the 3 bar has different colored wire
( green ) where the one you have has a tan. does the tan from the map plug go thru the the t-link harness possibly changing to green inside the harness then connect to the green wire that runs to the b terminal at the 3 bar? my hobbs is still pluged in & the loose ( analog plug ?) at the fender next to the hobbs is idle. do I need to do away with the t link harness ( datalogger on order ) reconnect the map, unplug the hobbs & use the ( analog harness concerned about the 5 volts & ground ) next to the hobbs to plug into the 3 bar. mind has turned to mush. the more I read the confuseder I get. done for the day. thanks

 

[Razor]

Razor, my t-link harness at the 3 bar is as following. a-blk, b green ( not c ), c-red. the harness that is next to the hobbs not used is as follows a-blk, b-green, c-grey.currently, my mat is unplugged, the mat harness ( grey & blk )is plugged into the t-link harness that goes to the tps, then from the tps it goes to the 3 bar. with this set up I have 1.57 volts at the green b terminal at the 3 bar. the blk that normally plugs into the mat, does show ground, but not from anything I have done

It looks like my t link boost harness at the 3 bar has different colored wire
( green ) where the one you have has a tan. does the tan from the map plug go thru the the t-link harness possibly changing to green inside the harness then connect to the green wire that runs to the b terminal at the 3 bar? my hobbs is still pluged in & the loose ( analog plug ?) at the fender next to the hobbs is idle. do I need to do away with the t link harness ( datalogger on order ) reconnect the map, unplug the hobbs & use the ( analog harness concerned about the 5 volts & ground ) next to the hobbs to plug into the 3 bar. mind has turned to mush. the more I read the confuseder I get. done for the day. thanks

To keep confusion down, its like this.

IF you get 1.5-1.6 volts on the center pin of the 3 bar MAP.. you have the correct wiring and correct +B and ground. And all you do is splice into the center wire and run that to the PAC controller.

Nothing else matters

Makes it easy if we simplify things

 

[pacecarta]

heres diagrams to help clear any confusion as to what connectors you need to find to make the jump and where they are in the car

 

[Razor]

Paul.. nice diagram

 

[ghall]

its in the instructs

flop open the glovebox the right side is a clear connector with foam around it that connects the engine harness to the dash harness , thats where youll be locating the wires on the engine side of the harness

you can jump 5v from the tps 5v to the ecm (pin C14 gray) to the map feed at the white connector on engine side of harness ,
youll need to jump ground from the tps ground (pin D12 Black) to the map ground at the white connector on engine side of harness
you can tap the map signal for the pAc from the same connector as you would for analog dash
you can then install the 3bar map under the hood to the factory connector and it will function and with key on should read 1.6v at the center pin (pin B) , pin C will have +5V and pin A should read ground , also double check at the map connection to the pac controller that you indeed have 1.6v key on

Thank you very much for taking the time to write this up. I used the search feature and this was the first thing that popped up----followed your directions for the power and ground but i was using this for a powerlogger install(digital dash car)---so obviously i had to run the map sensor output(green wire) to the powerlogger.


Thanks

Geoff

 

[2toneNV]

Does the 3 bar MAP sensor come standard on any GM vehicle?

 

[pacecarta]

Does the 3 bar MAP sensor come standard on any GM vehicle?

yes it was GM factory issue only the 89 turbo trans am
even if by some chance you found one in a yard (slim to none) the original sensor was not a plug and play for the GN

if you need one contact julio (aka razor of alkycontrol.com 727-570-9999) , he carries the ac delco TTA replacement 3bar sensor that is plug and play for the GN

 

[Razor]

Paul.. correct. The OEM 3 bar on a TTA had the +5 and Ground terminals reversed. So when a TTA owner bought a new 3 bar, they also had to buy a pigtail from GM to reverse the wiring.

We carry them.