12 / 5 volts to ECM

[swedtruck]

How many volts shoult it be int to the ECM box on a 6,2 -88, 2500 truck
5 ore 12 volts, i have onle 3,97 volt when engine is running.
and i have no 5 volt signal out to the map sensor..:::(

[diesel65]

You should have battery voltage at the inputs. There is a battery input and a ignition input to the computer.
There may be two battery and/or ignition inputs to the computer.
Check your grounds also.

[swedtruck]

battery input = 12 volt
ignition input = 5 volt ???

i have 3,9 volt on a input from fuse