Hello and welcome to just answer. That is not enough. It should be more like 5 or 8 volts. Are you checking it with the hall effect switch disconnected or connected?
Get back to me when you get a chance.
Ok, then there are a couple of things that may cause this. 1 another sensor that is shorted internally, or 2 a failed voltage regulator in the PCM. Do this: disconnect the map, tps, and the speed sensor one at a time and recheck the reference voltage at the hall effect switch. If the voltage comes back up after disconnecting a sensor, then that sensor is shorted and should be replaced. If the voltage does not come back up, then suspect a faulty PCM.
I am sorry, I just realized that this truck does not have a map sensor so ignore that. Now the speed sensor is in line with the speedometer cable and should be around the left side of the engine compartment.
You may have a short in the reference voltage circuit between the PCM and the Hall effect switch. Try this next: disconnect the PCM's connector (yes it is on the left fender) and disconnect the connector at the Hall effect switch. Then use an ohm meter to see if that circuit is shorted to ground. Put one lead of the meter on the reference voltage terminal at the switch end, and the other lead to a good engine or chassis ground. There should be no continuity (no reading on the meter). If there is then you will need to find and repair this. While the PCM's connector is off, inspect the terminals for corrosion, damage, etc.
Can you check continuity on the reference voltage circuit between the sensor and the PCM's connector? It should be the orange wire at the PCM connector.
You know what? I just realized that this truck does not have an actual Hall effect switch, but an old style pick up coil (2 wires correct?). Do this next. Measure the resistance of the pick up coil itself. It should be 150 to 900 ohms.
Ok that resistance appears ok. Try this next: disconnect the pickup coil connector, and with the ignition on. make and break connection on the pickup coil connector with a jumper wire and see if you can get the coil to spark by doing this.
Then that sounds like another bad ecm, unless you are missing a ground or battery / ignition feeds. Any blown fuses or fusible links?
It is starting to look like it huh?
Sure The J1 Pink wire on the larger connector should have 12 volts all the time. The J2 dark blue wire on the smaller connector should have 12 volts only when the ignition is on. The ground will be J9 which is the black wire on the smaller connector.