"Key-on" 12-volt source

[cherokee4.0]

Ok, call me a dummy...

I was just about to connect my new MAP adjuster to a CONSTANT 12-volt source when it occurred to me it was probably a bad idea.

I know the cigarette lighter will only work with the ignition on and the fuel pump also, but I don't want to pull the dash apart for the former case and the latter case has a 5-prong cube fuse that scares me.

I also noticed a grey connector that plugs into the top of my coil but I about broke my thumb trying to get it off (and still didn't get it off!).

Any suggestions where I can find an "ignition on" 120volt source?

Its a 98 4.0 4x4 auto. THANKS!

[langer1]

I thought the MAP adjuster connected to the 5 volt source?

[cherokee4.0]

No. Its 12 volts into the unit and about 5 volts out of it. The unit allows you to adjust your output voltage from around 4 volts to 6 volts.

I will set mine to about 5.6 volts and see what happens.

The output 5.6 volt line will be spliced into the stock 5-volt line that goes to the MAP sensor, and the stock 5-volt line source will just be taped off unused. On my 98, its the middle green line that will be spliced.

[langer1]

Your right I would use the 12 vdc wire going to the coil, it's one in the 3 wire plug.