anybody know where i can get a brain for a 97 TJ Sport for cheap ( less than 300 dollars )
Under $300, that is a good one. My brothers, friends, uncle's wife, once knew someone selling hens teeth. I think they also sold CPU's that cheep.
If it is getting fuel, is it squirting out of the test valve on the fuel rail when cranking or is it just dribbling out? Can you hear the fuel pump run when you turn the key on? If the fuel pump is not running can you hot wire it at the PDU (Power Distribution Unit), and make it run? Are you getting spark? Are all the relays in the PDU good? Are the proper contacts in the PDU getting power with key on, how about during cranking? If yes then the Ignition switch and wiring is ok. Are the Proper contacts in the PDU being grounded by the computer with the key on, how about during cranking? If not then the CPU of wiring to it is bad. Have you tried unplugging the CPU and cleaning the contacts with a good electric contact cleaner? Have you check the Crank Position Sensor CPS and its connections? These are know to go out and give similar problems. Is the computer giving any codes? If you turn the key on (without turning to crank) then off 3 times and then leave it on the computer should flash the check engine light. If every thing is okay it should flash five times and then pause and flash 5 more. Code=55. If it does not flash then do the other idiot lights work? If it flashes more then just the 55 what are those codes?
If you don't have a wiring diagram and multi meter get one.
Power for much of the engines electric systems, for example the fuel pump or ignition coil, flows as fallows. The actual power comes from the battery to the PDU, than trough a relay in the PDU, to the pump or coil. Power then grounded back to the battery through the frame on the case of the pump, or through the CPU in the case of the Coil.
Okay so what controls the Relay. Power for the relay comes from the battery through the ignition switch, to the PDU, it then flow through the coil on the relay and out to the CPU, the CPU than grounds the connection to complete the loop. So both the Ignition switch and the CPU need to be working And the CPU needs to want the pump to work, for the fuel pump or ignition coil to have power.
CPU's do go bad. The one in my Friends 97 Dodge went bad as determined by me, however given the cost we took it to a professional who confirmed the CPU was Bad. His was about $1000. To keep the EPA happy the CPU needs to come from the same model and year. So they are hard to find and often expansive if fallowing all the rules. The point I am trying to make is that there are many other parts the CPU works with that will make the CPU look bad, however those other parts are much cheaper to replace.