Data Master engine DTC error

Malf. 34 Map low
I swaped map sensors and still no luck .. does anyone know how to fix this problem? Thanks Sean

DTC -34 - MAP sensor, signal voltage low, high vacuum.

Terminal A = black wire = sensor ground from PCM (Ckt 470)
Terminal B = light green wire = MAP signal to PCM (Ckt 432)
Terminal C = gray wire = +5V reference from PCM (Ckt 474)

A loose wire..... the light green one or the gray one, can cause this problem.

With engine idling, does scanner snow MAP voltage below 0.25V?

No = no problem, probably intermittant
Yes?
Ignition off
Disconnect sensor harness connector
Jumper harness terminals B to C
Turn igntion on
Is MAP voltage over 4V?

Yes = faulty connection or sensor
No?
Ignition off
Remove jumper wire
Probe terminial B with a test light to battery voltage
Ignition on
Is MAP voltage over 4V?

Yes = 5V reference circuit open, or shorted to ground, or faulty PCM

No = Ckt 432 open
or
Ckt 432 shorted to ground
or
Ckt 432 shorted to sensor ground
or
Faulty PCM

thats what I needed to know thanks

when engine idiling I got like 1.4 volts.
With jumpers in place I got 4.99 volts. with car off ignition on.
So that should point out a wiring problem right or wrong? If right where do I need to trace these wires to to get a ohm's reading?
Thanks
Sean