94 Jetta 3

I have this 94 Jetta 2.0L and so when i hook the diagnostic computer it tells me theirs a problem with sensor (G40) Hall Sensor then it saids short with power as a description. This sensor is new and so is the distributor. The car runs rough and stalls the only way to keep it going is to accelerate a little. The car also seems to be making back fires into the intake. It seems to be out of timing so i have tested the timing and it seems fine. I have also replaced i think its a crank sensor just left of the starter. I have also replaced the ecm with a junk yard 1 which from what i am told has the letters AA at the end of the code which means the ecm is universal for 5 speed and automatic. This showed no improvement in the car. Ah and also the engine speed sensor is new. If you have any idea what ould be wrong please share

What type of code reader are you using? Code for a Hall effect sensor should br 00515 or a blink method code of 2113. Regardless, if you've replaced the distributor (& sensor) and the code still comes back, I'd say you have an intermittent bad connection. Your symptoms sound like there is a problem w/ignition system. Make sure you have good power to the hall effect sensor (I believe its at least 10V at the two outer terminals) w/ignition on. You can try jiggling the wires/connectors, especially where the harness attaches between the engine and body. Check the wire's resistance between the ECU & sensor, all must be less than 1.5 Ohm. I'd use the original ECU. Also, I have seen reman. distributor units that were bad.

I am using a snap-on scanner. I have tested to see if the wires were cracked using an ohm meter. All wires seemed fine. I have tested the outer wires of the hall meter and they are not 10 volts their half that 5.06 volts. Now when this happens i have read that a curcuit is messed up or the ecm is garbage. i also remmebered now that i put a new ignitor on the back of the coil. Now i have found that 1 wire from the hall sensor goes to the (tps) then to the ECM. Another is diretly to the ECM and of course 1 is ground. Now that i know that the hall sensor is not gettin enough juice and i have a new ecm in it. I wonder is it the ecm or where does the juice come from that goes to the hall sensor. Probly a relay of some sort by which?????

I'd start with that 5 Volts. The ground is at Hall sensor terminal #1 (brown/yellow) and goes to a ground lug near the fuel injection harness. Check resistance from this pin to battery ground, should be less than 1.5 Ohm or theres a problem. If you have a California car the power (pin 3 at the Hall sensor (black/yellow)) the is shared w/the throttle pos. sensor and comes from pin #41. You should have at least 10 Volts or theres a problem. If you have a regular Federal emissions vehicle Hall sensor pin #3 should be black/red and power comes from the power supply relay under the dash (same relay powers injectors, coil, evap purge sol. & O2 sensors). Again you should have at least 10 Volts or theres the problem. The Hall sensor center pin #2 (white/red) goes to the ECM pim #44. Resistance should be less than 1.5 Ohm or theres a problem. I don't have any good test for the sensor itself (I don't know if there is one), if after repairing the wiring and your getting at least 10 Volts to the sensor on pin #1 & #3 then replace the distributor/sensor.

I have a 94 Jetta too and my check engine light comes on when it gets moist or when it rains and the car runs like crap. The code says that it is the Hall Sensor. Where is this located?

Be carefull, the hall sensor code can be present when reading the engine codes because the engine is not running. The most common problem causing poor performance when wet is a cracke ignition coil housing. It is located on the firewall, just follow the center wire from the distributor. When it's dry & running okay spray it with water &
and see if it starts arcing & sputtering.

There is a thermo switch on the left side of the radiator, connect the solid red wire to either the red/white (low speed) or red/black (high speed) wires. If the fan runs then replace the switch.

Boschmann, should the car be running? And do you use a jumper wire to test them?

I don't think it matters, but turn the key on anyway. Use a wire or paperclip or whatever to jumper the connector's wires together.

My car turns off completely while i'm driving it. its a stick shift. it doesnt stall it just dies, the steering wheel locks up.my brakes stiff up and when I turn the car back on it jerks as if it were gasping for air.it doesn't need oil, gas, water or new fuses.

I take it that the engine dies & you put in the clutch pedal, what happens if you force the engine to continue to turn by not putting in the clutch pedal with the car still rolling? Will it fire back up or does it buck & kick or does it just turn the engine w/o no power until the car comes to a stop?

the car starts up again

You will need to determine if the engine is losing fuel or ignition spark, this can be difficult if it comes back to life too quickly. Listen to see if the fuel pump is making noise, how long since the filtewr was changed? Yo can feel the relays to see if one is getting hot & clicking on and off.

I was searching for references to code number 00515 and came across this thread. There is a test for the hall effect output. You hook a lab scope up, back probing the wire and watch the pattern with the engine running. The pattern should be a square wave. I understand that most people don't have a lab scope, I just wanted to clarify this for the sake of having all questions answered.