Hi i just bought this 93 civic ex i think 1.6l i have overcharging problem first it was charging at 20 v then i got a new alt now it is charging at 15-17v the blk/yel(ground i think) wire on the back of the alt has 35.8 Ohms on it and the wht/blu has 24ohm is there a short.
There are 4 wires hanging behind the fuse panel inside of the car that i dont know where they go
GRN/WHT-GRN/RED


BLU-Light GRN


You can see the green ones hangin


Also the tps ref voltage is battery voltage same with the map sensor.
Is my pcm fried or is there a short some where i checked all fuses with my dmm. Did a ground check and some of the fuses have 39ohms is its cause it is going through the pcm or is there a short to ground i dont know i have been working non stop trying to figure this out also the speedo stays at 20 mph then jumps to 70-100 while driving please help if you can isi there something i am missing i am new to hondas but i have ran test like i have on any other cars and i cant figure it out

Thanks in advance for everyones help

 

Look for modified wiring around the ECU. The ECU all grounds to the wires on the thermostat housing (engine end of the lower radiator hose). Pins A23 and A24 (black wires) on the ECU should be grounded. Pins D19 and D20 are the sensor power, 5 volts. Pin D17 and D22 are sensor ground, they are connected to ground inside the ECU but the sensors are not grounded externally.

Unplug plug D and measure ohms to ground from those sensor power and ground wires; with the ECU unplugged all the sensors should be completely isolated from the rest of the car (open circuit to ground). If it's not crossed wires and you really have 12 volts coming out of the ECU, it is bad.

The green and red wire may be for the brake warning light on the cluster. The green and white may be for the key / shifter interlock (if it is or was automatic transmission).

 

ok where are pins a23 a24 d19 d20 d17 d22 i have no idea where i am looking and i dont have a wiring diagram is there a down loadable one online or do you have a pic. I already took the fuse panel down to look for altered wires but found nothing so i dont know where to trace the wires back to.Should the fuse panel be grounded???

 

Those are pin numbers on the ECU (Engine Control Unit, i.e. the engine computer, what other manufacturers often call a PCM) plugs. The ECU is mounted under the carpet on the right side panel of the car where the passenger's feet would be.

There are places to download Honda service manual pdf's. Also the 1992-1995 Civic Haynes manual is (unlike most Haynes manuals) worth buying because it only covers one generation of models. It has a useful circuit diagram in the back.