Map adjuster.. Feeling kinda dumb..

[CobraMarty]

? So to use this, at WOT you have to 'flip' a switch? Really?

[cruiser54]

? So to use this, at WOT you have to 'flip' a switch? Really?

The 12 volts comes from a "switched" source meaning one that is only on when the ignition is on.

[CobraMarty]

My bad, you send the you send the 5.3v into the MAP sensor as the reference voltage, I thought it was the output voltage.

[showtime3492]

SO i finally had a lightbulg go off in my head and understood the whole map adjuster concept. Heres the problem now. I am reading 5.13 volts off the map supply without any modifications all i did was unplug the map and it is reading with the key in the on position 5.13 volts... Anyone know why this is? My jeep does have a mopar reman PCM in it. ill post pics

[showtime3492]

[CobraMarty]

Mine does the same thing. Everyone says 5.0v but it really gets 5.13v. I think that is so that if the ecu gets that high volt back the it throws a CEL and a 'bad MAP' sensor. If you turn on the key with the map plugged in, the signal v will be like IIRC 4.67-4.73v depending on your altitude.

[showtime3492]

Mine does the same thing. Everyone says 5.0v but it really gets 5.13v. I think that is so that if the ecu gets that high volt back the it throws a CEL and a 'bad MAP' sensor. If you turn on the key with the map plugged in, the signal v will be like IIRC 4.67-4.73v depending on your altitude.

Oh ok.. makes sense. I cant find a good 12v spot now. Anyone have any thoughts????

[Cheromaniac]

I am reading 5.13 volts off the map supply without any modifications all i did was unplug the map and it is reading with the key in the on position 5.13 volts... Anyone know why this is?

Probably a normal slight variation so don't sweat it. Even my own stock MAP reference voltage was 5.05v.

I cant find a good 12v spot now. Anyone have any thoughts????

OK, you're looking for a 12v feed that's only live when you have the ignition in the on position. The best one in the engine bay that you can tap into is the 12v wire to the electric fan relay.

[showtime3492]

I am reading 5.13 volts off the map supply without any modifications all i did was unplug the map and it is reading with the key in the on position 5.13 volts... Anyone know why this is?

Probably a normal slight variation so don't sweat it. Even my own stock MAP reference voltage was 5.05v.

I cant find a good 12v spot now. Anyone have any thoughts????

OK, you're looking for a 12v feed that's only live when you have the ignition in the on position. The best one in the engine bay that you can tap into is the 12v wire to the electric fan relay.

Ok i guess i should go track the wires form the electric fan relay. I was trying to follow what some other people had done and said there were switched 12v plugs there and just didnt see them as viable.

[Cheromaniac]

I was trying to follow what some other people had done and said there were switched 12v plugs there and just didnt see them as viable.

When people say use a 12v switched source, what they mean is a wire that has 12v supply ONLY when the IGNITION SWITCH is in the on position. Hope that helps you understand some of the terminology.

[showtime3492]

I was trying to follow what some other people had done and said there were switched 12v plugs there and just didnt see them as viable.

When people say use a 12v switched source, what they mean is a wire that has 12v supply ONLY when the IGNITION SWITCH is in the on position. Hope that helps you understand some of the terminology.

Yeah i understand that. One more question is it best to tap into the fan relay wires right under the power dist center or elsewhere?

[showtime3492]

The first place i checked was where the electric fan plugs up for a switched 12v and it didnt show anything on the multimeter so i figured there was only 12 v there when it was needed or somethin. Im such an electronics noob lol

[Cheromaniac]

One more question is it best to tap into the fan relay wires right under the power dist center or elsewhere?

The switched 12v wire that goes into the fan relay (fairly sure it's terminal 87 of the relay) is as good as any to tap into.

[showtime3492]

One more question is it best to tap into the fan relay wires right under the power dist center or elsewhere?

The switched 12v wire that goes into the fan relay (fairly sure it's terminal 87 of the relay) is as good as any to tap into.

I got it installed and working properly. Thanks to everyone for the information. This is an awesome forum.

[Cheromaniac]

I got it installed and working properly. Thanks to everyone for the information. This is an awesome forum.

Glad you got it working.