If anyone read my other post about the Code 42/43, changed knock sensor, no more code 42 or 43 but no difference in performance.. But now have code 53, system voltage too high - I checked battery and its reading about 18 volts with car off.. Disconnected alternator and still getting system voltage to high.. Will this make car act like it is? will not rev past 3500, acts like a rev limiter kicking in, just not as smooth - and sounds like it loses all spark or fuel during that time as the engine sounds dead for that moment...

Any help would really be apprecated in trouble shooting this..........

Is there something wrong with the new battery I put in? would that cause it to do what its doing?? something else giving me that false code maybe - though it seems battery voltage is high..

The battery and wiring harness are both new and changed same time during engine/pcm swap..

going to try different battery now, but really doubt thats the problem..

 

Car battery charged to 18 volts........flat out dangerous. Before you start that thing, check/ohm the alternator feedback wire (for voltage regulation) and the connection at the alternator. If that is fine, check the voltage regulator in the alternator. It sounds like the alternator wiring is messed up or the voltage regulator is bad.

I would not run that thing until you fix this. Batteries can explode when gasing a lot from overcharging.

EDIT: If you keep hammering the electronics in the car with too much voltage, they are are going to be destroyed. Including the ECM. If you decide to drop in the new/other battery, MAKE sure you disconnect the alternator output wire and measure the voltage with the car running.

 

Just fixed it!! wooooo hoooo!!!
Well I checked my other car, and my truck battery and they measured same 17-18 volts - must have inaccurate tester!! however I checked the ignition power feed to Ecm that I stole off airbag control and its reading 39 volts!!!!!!
They must use some sort of capacitor or something.. I hooked it to battery for a moment and car now revs!! Weird!

Just for a little history,
Swapped my 7730 ecm and 406 into a 94 firebird transplant car.. So airbags and alot of other things are no longer funtional due to factory ecm no longer in use.. Future reference! when the wires say "do not cut for any reason" find another..
Was having hard time finding ignition power anywhere near ecm, that was the one I found..


Thanks for help.